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dissertation entitled

SCI-HSTOSOMIASIS JAPONICUM TRANSMISSION
AND CONTROL IN A PHILIPPINE VILLAGE

presented by

Renato L. Cerdefla

has been accepted towards fulfillment
of the requirements for

PhD- degree in Qmmphy

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SCHISTOSOMIASIS JAPONICUM TRANSMISSION
AND CONTROL IN A PHILIPPINE VILLAGE

By

Renato L. Cerdefia

A DISSERTATION

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Geography

1995

ABSTRACT

SCHISTOSOMIASIS JAPONICUM TRANSMISSION
AND CONTROL IN A PHILIPPINE VILLAGE

By

Renato L. Cerdefia

Schistosomiasis japonicum is a major public health challenge in small irrigation
systems in the southern part of the Philippines. Public attention to its threat, however, is
focused mainly on large water development and irrigation projects that benefit thousands
of hectares of agricultural land. Small, dispersed units of water impoundments and
irrigation systems that are managed by farmers and informal irrigators’ associations have
been neglected by health authorities and researchers. Yet, it is likely that these small
impoundments and irrigation systems, in their totality, have an equally great or greater
significance for human health. The rice and coconut farming village of Macanip on Leyte
Island, Philippines illustrates the need to conduct a systematic investigation of the spatial
distribution of and problems of schistosomiasis transmission in small irrigation systems.
Despite annual chemotherapeutic control efforts, a review of the annual prevalence rates
in the village over the last decade shows that after a significant drop in the first two years
of screening and treatment, schistosomiasis prevalence rates have gradually risen: in 1992,
the prevalence rate was 48 percent, three points higher than the pre-treatment level of 45

percent in 1982.

This study investigates the factors leading to the persistence of schistosomiasis

japonicum in the village of Macanip, Jaro, Leyte, Philippines. It contends that the

transmission and control of schistosomiasis japonicum can best be understood by using an

analytical framework modeled after the transmission cycle of the parasite.

A total of 251 household heads in the village were interviewed to gather data on
demography, water contact behavior, living conditions, household expenses and income,
livelihood, ownership of animals, health seeking behavior, knowledge of the
schistosomiasis transmission cycle, community perceptions, attitudes and outlook,
community participation, and attitudes and perceptions toward schistosomiasis. The

Research Institute of Tropical Medicine provided parasitological and water contact data.

The persistence of schistosomiasis in the village is due largely to the failure of
villagers to understand the roles of the human host and the animal reservoirs in the
transmission cycle. Water contact patterns show that the highest frequency of water
contact involve crossing canals and streams. The longest duration of exposure involves
work in the rice fields. The children in this village are always at risk because they are
assigned the role of collecting drinking water from springs along infected creeks and
streams. Although the people are generally aware that schistosomiasis is acquired through
water contact, poverty leaves them no choice but to engage in activities that expose them
to potentially infected waters. The regular arrival of schistosomiasis control teams has
also led to a dependence among villagers on chemotherapy. Very little is done to avoid
water contact since they know that they can always take praziquantel to control the
disease. The potential for reinfection remains very high despite almost complete treatment
of human hosts because of the presence of substantial numbers of animal reservoirs such

as dogs, pigs, and field rats.

DEDICATION

To my wife and children, Victoria, Angelica and Leon,

and to my parents, Rosalina and Tranquilino.

iv

ACKNOWLEDGEMENTS

I wish to thank the following for their support during the various phases of this

study:

Dr. John M. Hunter, my adviser, for his guidance, encouragement and learned
advice; and to the other members of my doctoral committee: Dr. Michael Chubb, Dr.
Daniel Jacobson (deceased 29 March 1995), Dr. Richard Groop, and Dr. Gary Manson for
their excellent suggestions and helpful comments.

The Department of Geography, Michigan State University, especially to the former
Chairperson, Dr. Judy Olson, for the financial support in the form of a teaching

assistantship during my doctoral studies;

Dr. Telesforo W. Luna, Jr., Chairman, Department of Geography, University of
the Philippines for encouraging me to pursue doctoral studies at Michigan State
University;

Dr. Remigio Olveda, Director of the Research Institute of Tropical Medicine
(RITM), for giving me permission to use parasitological data and water contact
observation data gathered by RITM in Macanip; Dr. Gemiliano Aligui, for providing the
parasitological data and giving the background on the methods of how the data were

gathered; and Dr. Bernadette Ramirez for her practical suggestions;

Dr. Bayani Blas, Director of the Schistosomiasis Control Service, Department of
Health, for sharing his wealth of experience on schistosomiasis japonicum in the

Philippines and for providing materials on previous schistosomiasis surveys and studies in

the country; Dr. Lydia Portillo, Officer in Charge, Schistosomiasis Research and Training
Division in Palo, Leyte; Dr. Anita Balles-Aragones, Provincial Schistosomiasis
Coordinator of Leyte, for providing data and insights on the schistosomiasis situation in

Leyte;

Engineer Sadiqul Bhuiyan of the Water Management Division, International Rice
Research Institute (IRRI), for providing reference materials on vector-home diseases and

water resources development;

Mr. Virgilio Santos, National Cartographic Authority, Fort Bonifacio, Makati,
Metro Manila, for his assistance in the procurement of 1:50.000 and 1:250,000
topographic maps covering the study area; Mr. Joe Dilig, Vice President of the Certeza
Development Corporation, who helped me procure aerial photographs of Macanip; Mr.
Fidel Adal, Flaming Officer, Department of Environment and Natural Resources, Region
VII, and Mr. Leon Estardo, Cartographer, Lands Management Service, Bureau of Lands,
Region VIII, for their assistance in providing maps of the study area; Mr. Edgardo
Villena, EDP Coordinator, National Economic Development Authority Region VIII in
Leyte and Dr. Teodoro Santos, National Institute for the Geological Sciences in Diliman,

Quezon City for allowing me to use their computer facilities in digitizing my maps;

Mr. Rufo Ribo, town mayor of Jaro, for facilitating my requests for municipal data;
Dr. Bienvenido Borden, Municipal Agricultural Officer of Jaro, Leyte, and Mr. Noel
Vertez, Agricultural Technologist in charge of Macanip, for providing an overview of the

agricultural situation in Macanip and the other villages of Jaro;

Mr. Arturo and Juanita Adlawan, my hosts in Macanip, for their hospitality; Mr.
Bienvenido Arbas, village councilman and Unit 3 leader, who acted as my interpreter and
guide; Mr. Serafm Mannita, President of the Irrigators’ Service Association in Macanip,
who discussed the irrigation situation in Macanip; the unit leaders of the village: Mr.

Abraham Sorila (Unit 1), Mr. Wenceslao Maroto (Unit 2), Mr. Eusebio Macanip (Unit 4),

vi

Mr. Sofronio Macanip, Jr. (Unit 5), Mr. Jovito Maroto (Talisay), Mr. Juan Caraballa, (San
Antonio), Mr. Quintin Colaba (Cagambahan), Mr. Ambrosio Colaba (Morokborok), Mr.
Salvador Artoza (Gapas), Mr. Abraham Doble (Hambabalod), Mr. Herminio Meridor
(Cutay-Sapa), and Mr. Metodio Tamayo (Guinwalohan), for their assistance during my

interviews of residents in their respective units; and

My sister-in-law, Mrs. Rosario Santos-Ng, who was a caring aunt to my children
and concerned sister and adviser to my wife, and whose generosity immensely helped
during the financially difficult period of my doctoral studies; and my other in-laws in New
Jersey, Mr. Rogelio and Regina Santos-Febrin, Mr. Rolando and Rustica Santos, Mr.

Ramon Santos, and Carlos Santos, Jr. for their help and kindness.

TABLE OF CONTENTS

Page
List of Tables .................................................................................. xi
List of Figures .................................................................................. xiv
Chapter 1. The Problem ................................................................................... 1
Background of the Problem ............... 1
Statement of the Problem ............................................................ 10
Chapter 2. Review of Related Literature ........................................................... 12
The Parasite ................................................................................ 12
The Snail Intermediate Host ........................................................ 14
Animal Reservoirs ....................................................................... 16
Human Pathology ........................................................................ 17
Snail Control ............................................................................... 29
Chemotherapy ............................................................................. 33
Chapter 3. Methodology ................................................................................... 37
Analytical Framework ................................................................. 37
Hypotheses ................................................................................. 38
Selection of Study Area ............................................................... 40
Recruitment of Field Guide and Interpreter .................................. 42
Socioeconomic Survey ................................................................ 43
Field Mapping and Aerial Photointerpretation .............................. 45
Village Census ............................................................................ 46

 

 

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Snail Infection Data ..................................................................... 46

Parasitological Data .................................................................... 47
Water Contact Data ................................................................... 49
Chapter 4. Village Profile ................................................................................. 53
Physical Environment .................................................................... 53
Climate ....................................................................................... 56
Surface Waters ............................................................................ 57
Settlement Pattern ....................................................................... 59
Slope and Elevation of the Land .................................................. 61
Soils ............................................................................................ 61
Socioeconomic Characteristics ...................................................... 63
Population .................................................................................. 63
Rice Cultivation .......................................................................... 65
Irrigation .................................................................................... 66
Night Irrigation and Night Fishing ............................................... 67
Coconut Cultivation .................................................................... 69
Family Income and Expenditure .................................................. 69
Animal Husbandry ...................................................................... 72
Rat Population ............................................................................ 74
Sources of Water for Domestic Use ............................................ 75
Use of Toilets ............................................................................. 76
Chapter 5. Water Contact and Risk of Transmission ........................................... 80
Description of Water Contact Study Area .................................... 80
Transmission Risk: Snail Infection ............................................... 83
Gender and Age Differences in Water Contact ............................. 86
Frequency of Different Types of Water Contact by Season .......... 88
Frequency of Water Contact by Type of Water Body .................. 90

ix

Duration of Water Contact Activities .......................................... 90

Duration of Water Contact: Differences by Season, Type

of Activities, and Type of Water Body ......................................... 94
Frequency of Water Contact at Various Times of Day ................. 98
Chapter 6. Prevalence and Intensity of Human Infection ..................................... 99
Prevalence of Schistosomiasis ..................................................... 99
Intensity of Infection ................................................................... 101
Chapter 7. Disease Perception and Control ........................................................ 110
Chapter 8. Conclusions and Recommendations ................................................ 123
Bibliography ............................................................................................................ 133
Appendix Macanip Schistosomiasis Survey (Interview Schedule) ................... 140

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LIST OF TABLES

Page

3.1 Macanip Schistosomiasis Infection Records ................................................. 48

3.2 Water Contact Observation Sites ................................................................. 50

3.3 Number of Water Contact Observations Per ................................................ 51
Site, 1992 and 1993

4.1 Rainfall and Temperature by Month, 1951-1985. ........................................ 57
Tacloban City

4.2 Population by Sex and Age Group ............................................................... 63

43 Number of Respondents Who Engage in Night Irrigation ............................. 68
and Night Fishing

4.4 Frequency of Night Irrigation and Night Fishing ........................................... 68

4.5 Family Income and Expenditure by Zone, 1993 ............................................ 71

4.6 Amm' al Population Raised in the Survey Households, ..................................... 74
March, 1993

4.7 Uses of Different Sources of Water, March, 1993 ........................................ 75

4.8 Number of Toilets, 1993 .............................................................................. 77

4.9 Reasons for Not Having a Toilet .................................................................. 77

4.10 Usual Defecation Area of Respondents Who Do Not HaveToilets 78

5.1 Snail Infection by Season and By Site ........................................................... 84

5.2 Frequency of water contact activities at 31 observation posts ........................ 87
by sex and age group

5.3 Frequency of water contact activities at 31 observation .............................. 89
posts by season

5.4 Frequency of water contact activities at 8 water types ................................ 91
by sex and age group

5.5 Frequency of water contact at 8 water types by age group and season ......... 92

xi

5.6
5.7

5.8
5.9

5.10

6.1

6.2

6.3

6.4

6.5

7.1

7.2

7.3

7.4
7.5

7.6

7.7
7.8

Duration of water contact activities at 31 observation posts ......................... 93

Duration of water contact activities at 31 observation posts ........................ 95
by season
Duration of water contact at 8 water types ................................................... 96
Duration of water contact at 8 water types by season .................................. 97
Frequency of water contact activities at various .......................................... 98
times of the day
Prevalence and Intensity of S. japonicum Infection by Gender ...................... 105
and by Year, 1982-1992, Macanip, Jaro, Leyte, Philippines
Prevalence and Intensity of S. japonicum Infection by Gender ...................... 106
and Age, ll-Year Means, 1982-1992,
Macanip, Jaro, Leyte, Philippines
Prevalence and Intensity of S. japonicum Infection ...................................... 107
by Gender and Age, 1992, Macanip, J aro, Leyte, Philippines

. Prevalence and Intensity of S. japonicum Infection by Gender ..................... 108
and by Zone, ll-Year Means, 1982-1992,
Macanip, Jaro, Leyte, Philippines
Prevalence and Intensity of S. japonicum Infection by Gender and ............... 109
by Zone, 1992, Macanip, J aro, Leyte, Philippines
Source of Information on Schistosomiasis .................................................... 111
Sources of Information Regarding Local and ............................................... 112
National Affairs
Can Schistosomiasis be Transferred Directly from ....................................... 113
One Person to Another?
Knowledge of the Elements of the Transmission Cycle ..... I ........................... 113
Knowledge on Places Where Schistosomiasis is Acquired ............................ 114
Awareness that Schistosomiasis is Acquired through ................................... 115
Cercarialfi Penetration of the Skin
Knowledge on How to Avoid or Prevent Schistosomiasis ............................ 116
Place of Treatment for Ordinary Illnesses ..................................................... 117

7.9 Place of Treatment for N on-ordinary or Emergency Illnesses ....................... 118
7.10 Place of Treatment for Perceived Schistosomiasis Symptoms ....................... 119

7.11 Most Important Problems of the Village ....................................................... 120

1.1
2.1
3.1
4.1

4.2

4.3

4.4

5.1

5.2

6.1
6.2
6.3
6.4
6.5
6.6

LIST OF FIGURES

Page
Life Cycle of S chistosoma japonicum .................................................... 4
Schistosomiasis Endemic Provinces of the Philippines ........................... 22
Model of Schistosomiasis Transmission and Control ............................. 39
Map of Leyte Province, Philippines ........................................................ 54
Settlement Pattern and Land Use, .......................................................... 55
Macanip, Jaro, Leyte, Philippines
Mean Temperature by Month, 1951-1985, ............................................. 58
Tacloban City, Philippines
Average Rainfall and Rainy Days by Month, 1951-1985, ......................... 58
Tacloban City, Philippines
Water Contact Observation Area ............................................................ 81
Transmission Risk' Prevalence of S. japonicum
Infection of Snails by Season .................................................................. 85
Prevalence Rate, 1982-1992 ................................................................... 100
Age Prevalence, 1982-1992 ................................................................... 100
Age Prevalence, 1992 ............................................................................ 103
Intensity of Infection, 1982-1992 ........................................................... 103
Intensity of Infection by Age Group ....................................................... 104
Intensity of Infection by Age Group, 1992 ............................................. 104

xiv

CHAPTER 1

THE PROBLEM

The purpose of this study is to investigate the factors leading to the persistence of
schistosomiasis japonicum in the village of Macanip, J aro, Leyte, Philippines. This study
is founded on the concept that the transmission and control of Schistosomiasis japonicum
can best be understood by using an analytical framework modeled after the transmission
cycle of the parasite. The main elements of the transmission cycle are parasitic flukes,
human hosts, snails, animal reservoirs, and the environment in which they all interact.
Since humans have an overwhelming influence on their environment, this study examines
human behavior and practices in the study area to anive at a better understanding of

schistosomiasis transmission and control.

Background of the Problem

Schistosomiasis is one of the most important tropical diseases in the Philippines. It
is outranked only by malaria and tuberculosis among the leading causes of morbidity in
that country. Within the 24 provinces where schistosomiasis occurs, there are 1,152
endemic villages in 169 municipalities. The total exposed population, defined as the
population of the endemic municipalities, is estimated at more than 6 million, or about 10
percent of the Philippine population (Blas, Bautista, and Lipayon, 1990; Schistosomiasis
Control Service, 1987). In spite of continuing control efforts of the government with the

help of international agencies such as the World Health Organization and World Bank,

1

2

schistosomiasis continues to be a menace in many areas where water resources
development, farming practices, and human settlement maintain or create additional
transmission sites. A comprehensive knowledge of the environmental, demographic,
social, human behavioral, and economic factors that influence the transmission of
schistosomiasis japonicum is indispensable for the design of control programs that are

sustainable over a long period.

Schistosomiasis is a chronic debilitating disease caused by the schistosome, a
parasitic worm of the trematode class. The three major species of schistosomes that infect
humans are Schistosoma japonicum, S. mansoni, and S. haematobium. Controversy still
prevails as to whether S. mekongi is a separate disease-causing schistosome or a variant of
S. japonicum. These human schistosomes differ in the morphology of the adults, the size
and shape of their eggs and the larvae which hatched from the eggs. Another difference
lies in their infectivity to the particular groups of snails that they utilize as intermediate
hosts and in their infectivity to other mammalian hosts. S. haematobium worms live
within the capillaries on the wall of the human bladder and the other two species dwell
within the blood vessels of the intestines. The adult male worm is shorter and thicker than
the longer, slender female worm. The male has a longitudinal body groove in which the
female normally remains. Adult worms mate in the liver and make a paired migration
against the flow of blood until they reach the smallest venules of their predestined
location. The favored eventual location of the adult worm and, consequently, egg
deposition, varies according to species: S. haematobium is concentrated near the bladder,
S. mansoni favors the large intestine, and S. japonicum prefers the large and small
intestine. The eggs accumulate and press on the tissues producing ulcerations and sores

through which they are passed out in the feces (Webbe, 1982).

3

The parasite responsible for schistosomiasis in the Philippines is S. japonicum.
The characteristics that differentiate it from other human schistosomes have been

described by Mott (1982, p. 128):

S. japonicum represents the extremes of biological characteristics of the human
schistosomes. The developmental stages in the snail require the longest period of
time, up to 10 weeks; a longer exposure to light is necessary before cercariae are
shed, and yet the daily rate of cercarial shedding is the lowest. The adult worms are
the largest, yet the eggs are the smallest. In man, the female worm excretes eggs in
clumps, not singly, and in greater numbers than other schistosomes. The worm is
found in a wider range of animals than the other schistosomes. . . .

Although the life cycles of these parasites are, in general, similar to those of
. S. haematobium and S. mansoni, certain aspects of the life cycle of S. japonicum as
well as some responses of the human body to it are very different, which results in
differences in epidemiology, disease processes, and control of S. japonicum.

The basic life cycles of human schistosomes are similar (Figure 1.1). Human
schistosome eggs hatch only in fresh water. Once in the water, which may be flowing or
stagnant, the eggs hatch into miracidia, the first free-swimming larvae that infect the snails.
The larvae require a freshwater snail as an intermediate host. In the Philippines, this
function is performed by the Oncomelania quadrasi snail only. The miracidia must find
the appropriate snail host within 48 hours or die. The worm must spend part of its life in
this snail before it can develop into a form that can infect humans. On the basis of studies
done in the Philippines, the average time between miracidial penetration and shedding of
cercariae is 62 days for snails infected with a single miracidium or 64 days for multiple—

infected snails (Garcia, 1976)

Inside the snail, the miracidia undergo asexual reproduction and metamorphose
into the infective cercaria form. A snail inhabited by a single miracidium can expel several
thousand cercariae, the second free-swimming larvae of the schistosomes. It is this second
larval stage that infects human and animal hosts. Cercariae emerging from the same snail
are the same sex as the original miracidium, although snails may be infected by many

miracidia and thus shed cercariae of both sexes.

 

Caeariae
penetrate
the skin

 

 

 

 

Miracidium penetrates
soft ts of suitable

m ' host, which is
Oncomelania quadrasi

'n the Philippines

Life Cycle of Schistosomajaponicum

 

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Adult male and f ernale
worms live in copula in
the portal vessels

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Free-swimm'ng
cercariae leave snail
to find host

 

 

Eggs are laid in
terminal capillary
vessek in intestinal
wall & through
ulceration reach

the feces

 

 

 

 

 

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Matured egg pmsed out
in the feces hatches into
a miracidium upon
contact with wata

RIC 1995

 

Fi

gure 1.1 Life Cycle of Schistosonrajaponicum. Source: Schistosomiasis Control

Service. 1988. Schistosomias‘s Brochure. Manila: Department of Health.

 

Infection of humans occurs if the unprotected skin of a person is brought into
contact with cercariae-infested water. The likelihood of infection increases with the length
of time that the skin is exposed to water. Male and female cercaria penetrate the skin and,
once inside the body, shed their tails to change into a form called schistosomules. The
worms then move through the tissues to the circulatory system within which they migrate,
by way of the heart, lungs, and liver (where they mate), to the bladder or intestine and so

completing the cycle of the disease.

The duration of one complete cycle in animal and human hosts is approximately
three months: intra-molluscan development is about two months while development within
the human host takes a month. Experiments of Pesigan, Farooq, Hairston, Jauregui,
Garcia, Santos, Santos, and Besa (1958a) on mice have shown that the time it takes
between cercaria] penetration and laying of eggs of the female worm ranges between 23
and 27 days. The mature eggs take about 10 days to develop into miracidia (Garcia,
1976). For passing of eggs to the feces to occur, it is thought that a threshold value of the
number of eggs in the intestinal wall needs to be exceeded. This value is reached sooner
when the worm burden is higher than when only a few worm pairs are present (Hinz,
1985). There are no fixed estimates of the time it takes for eggs to move from the

intestinal wall to the feces.

The most prevalent form of the disease is chronic schistosomiasis, the severity of
which is directly related to intensity of infection. It causes weakness, anemia, bloody urine
or stools, diarrhea, and, due to the organ’s reaction to the accumulation of eggs, inflam-
mation of the liver and spleen. Another form, acute systemic schistosomiasis or Katayarna
fever is characterized by abrupt onset of high fever, chills, abdominal pain, diarrhea, nau-
sea, and vomiting. It occurs two to three weeks after heavy initial infection, at the time of

first egg release, and may last one or two months (Katz, Despommier, and Gwadz, 1989).

t

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39.

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In its 1993 report, the World Health Organization’s Expert Committee on Schis-
tosomiasis estimates that about 200 million pe0ple in 74 countries are infected with one or
more of the Schistosoma species (WHO, 1993). The global magnitude and distribution of
the schistosomiasis problem is visually apparent in the Atlas of the Global Distribution of
Schistosomiasis (Doumenge, Mott, Cheung, Villenave, Chapuis, Perrin, and Reaud-Tho-
mas, 1987). Despite the success of control programs, the WHO estimate has not changed
since 1984, largely because of population increases in countries where the disease is en-
demic. According to WHO, the public health significance of schistosomiasis is often un—
derestimated for two reasons. First, only few people in a community typically haVe severe
infections and heavy worm loads while the rest of the community have light infections and
show fewer symptoms or none at all. Second, it takes many years of mildly symptomatic
infection before severe disease develops. Frequency and severity of schistosomiasis-re-
lated disease, incapacity, and premature death were suggested as measures to assess the

public health impact of the disease.

Globally, the geographic distribution of schistosomiasis is confined to an area be-
tween 36 degrees north and 34 degrees south latitude, where freshwater temperatures av-
erage 25° to 30°C. Infections with S. japonicum are found only in East Asia, primarily in
China, Malaysia, Indonesia, the Philippines, and Japan. Dogs, monkeys, rats, pigs, and
cattle serve as its important reservoir hosts. S. mekongi is found in northeastern Thailand,
Laos, and Kampuchea. The snail intermediate hosts of S. japonicum belong to the genus
Oncomelania, which is amphibious and spends much of its time out of water, prefening
moist soil at the edge of slow-flowing streams or irrigation canals. For S. mekongi,
Tricula aperta is the natural snail host (Kitikoon, 1984). Infections with S. mansoni and
S. haematobium prevail throughout much of Africa, parts of Southwest Asia, the Carib-
bean, and South America. S. haematobium is endemic in 54 countries of Africa and the

eastern Mediterranean; S. mansoni is endemic in 52 countries and territories of South

11C.
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America, the Caribbean, Africa, and the eastern Mediterranean; and in 41 countries of Af-
rica and the eastern Mediterranean, both parasites are present (WHO, 1993). The aquatic
snails important in the transmission of these two parasites live in lightly shaded, slow-
flowing (15 meters/minute), shallow (< 2 meters) water. S. mansoni is transmitted from
person to person through snails belonging to the genus Biomphalaria. There are only a
few known reservoir hosts, such as baboons and monkeys in Africa, and they usually do
not transmit the infection to people. The intermediate hosts of S. haematobium are mem—
bers of the genus Bulinus; the parasite has no important reservoir hosts other than humans

(Laughlin, 1984).

Throughout the world, schistosomiasis is increasing in prevalence largely because
of increased exposure to contaminated water associated with (1) wider use of irrigation
for agricultural development; (2) population increase and movements; and (3) inadequate
control measures. Human cultural habits of bathing, playing, and defecating and urinating
in the same freshwater supply, as well as agricultural practices requiring intense human
water contact are critical to the maintenance of the disease cycle. Endemic populations
show human infection beginning as early as 6 months of age. The peak intensity and
prevalence of infection, as measured by egg excretion, usually occur between 8 and 12
years of age in heavily infected communities and somewhat later in lightly infected areas.
Most endemic populations will have a 40% to 60% prevalence rate of schistosome egg
excretion at any one time; but almost everyone (Le, 95%) will experience an infeCtion

during a lifetime (Laughlin, 1984).

Schistosomiasis control encompasses two parallel independent strategies: control
of population morbidity and control of transmission. It includes five (5) general methods:
chemotherapy, snail control, reduction of water contact and contamination, vaccination,
and improved living standards. Chemotherapy has two broad objectives: in the individual

patient, to eradicate infection--successful treatment will stop further deposition of eggs

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preventing further tissue damage and existing lesions will often regress; for the commu-
nity, the cessation of egg excretion will block the egg/miracidium/snail stage of the bio-
logical cycle, thereby reducing transmission (Davis, 1982). A new generation of antischis—
tosomal drugs are available that can be given safely in the field in single (or only a few)
doses, that can cure at least 75% of those infected, and that reduce ova excretion by 90%
to 95% in those not cured: oxamniquine for S. mansoni infections; metrifonate for S. hae-
matobium infections, and praziquantel for S. mansoni, S. haematobium, and S. japonicum
infections (Laughlin, 1984). The drug of choice in the Philippines is praziquantel, which is
available under the trade names Biltricide of Bayer AG, Germany or Distocide of Shin
Poong Pharma, South Korea. The drug is dispensed in lacquered tablets containing 600
mg of praziquantel. Given in the proper dose of 3 x 20 mg/kg body weight at intervals of
four (4) hours, it is highly effective while producing only minor side reactions

(Schistosomiasis Control Service, 1987).

Snail control is a rapid and effective means of reducing transmission. The usual
method of snail control is mollusciciding. Chemical compounds are generally used, but
plant molluscicides have been the focus of recent research (Mott, 1987). Due to the lim-
ited funds for chemical control of snails in the Philippines, mollusciciding is used after
clearing of vegetation and drainage of waterlogged areas when snails are confined to ini-
gation canals and resistant pockets. This is known as terminal mollusciciding. An alter-
native method of snail control is biologic control in which potential competitors or preda-
tors (including ducks, fish, turtles, fungi, and parasites) are introduced into the environ-
ment Environmental modification, which involves the burying of snails by digging out
irrigation ditches, was an effective but labor-intensive method of Oncomelania snail con-
trol in China. Other methods of environmental modification, e.g., cementing over or en-
closing irrigation ditches, not only reduces the snail habitat but also diminishes human ex-

posure to water (Laughlin, 1984; Blas, 1976; Schistosomiasis Control Service, 1987).

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In the Philippines, the geographical distribution of the parasite is coincident with
that of the snail host Oncomelania quadrasi. Schistosomiasis is endemic in 24 provinces
situated between 6°20’ N - 13°20’N and 121°15’ - 126°25’E (see map on p. 22). Within
these boundaries, the environmental requirements of the snail intermediate host
Oncomelania quadrasi dictate the local distribution of the disease. Since these snails
cannot tolerate a long dry season and a high velocity of water flow, schistosomiasis is
restricted to the lowland plains and plateaus with high rainfall evenly distributed

throughout the year.

The disease is prevalent in the rural areas of the Philippines and it affects mainly
the rural poor. It exerts significant and disruptive influences on nutritional reserves and
growth from middle childhood through adolescence (McGarvey, Aligui, Daniel, Peters,
Olveda, and Olds, 1992). It hampers agricultural productivity because it affects mostly
farmers and their families especially young age groups including children and young adults
aged 15-24 years. More males are affected than females, particularly those who earn their
living as laborers and fresh-water fishermen. Its deleterious effect on the productivity of
agricultural workers was revealed in a 1987 study that showed that among those afflicted
an average loss of 41.6 days per year are lost due to disabilities engendered by the disease

(Blas, 1988).

Schistosomiasis in the Philippines has an important zoonotic aspect. Many species
of wild and domestic animals have been found to be infected, including field rats, dogs,
cows, pigs, goats, and carabaos (water buffalo). These reservoir hosts play a very impor-

tant role in transmitting schistosomiasis in endemic areas of the Philippines.

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Statement of the Problem

Schistosomiasis japonicum is a major public health challenge in small irrigation sys-
tems in the southern part of the Philippines. Public attention to its threat, however, is fo—
cused mainly on large water development and irrigation projects that benefit thousands of
hectares of agricultural land. Small, dispersed units of water impoundments and irrigation
systems that are managed by farmers and informal inigators’ associations have been ne-
glected by health authorities and researchers. Yet, as has been observed in other parts of
the world, it is likely that these small impoundments and irrigation systems, in their total-
ity, have an equally great or greater significance for human health (Hunter, Rey, Chu,
Adekolu-John, and Mott, 1993; Hunter, Rey, and Scott, 1982; Doumenge, et a1, 1987).
Usually there is a high degree of contact with water by people and animals, so that disease
transmission rates, especially for schistosomiasis japonicum which has an important
zoonotic aspect, are considerable. Once schistosomiasis is endemic in a rice irrigation
scheme, its control is a long-term and expensive, but feasible, operation. As has been in
the past, control of schistosomiasis in areas of inigated rice production will be a major

challenge in the future (Bergquist, Chen, and Mott, 1988).

The rice and coconut farming village of Macanip in Leyte Island, Philippines, illus-
trates the need to conduct a systematic investigation of the spatial distribution of and
problems of schistosomiasis transmission in small inigation systems. Despite annual che-
motherapeutic control efforts, a review of the annual prevalence rates in the village of
Macanip over the last decade shows that after a significant drop in the first two years of
screening and treatment, schistosomiasis prevalence rates have gradually risen: in 1992,
the prevalence rate was 48 percent, three points higher than the pretreatment level of 45
percent in 1982. This illustrates the inadequacy of relying on chemotherapy alone to con-

trol schistosomiasis: annual chemotherapy reduces the prevalence and incidence of

11

infection but cannot by itself eradicate infection. It also reflects the fact that previous
investigations were aimed at an understanding of the disease with the end in view of
targeting vulnerable points in the transmission cycle for drugs and vaccines to kill the
parasite, and molluscicides to kill the snail intermediate host The dynamic relationships
involving the social, environmental, and water contact aspects of the disease have largely

been ignored

Information on the different elements of the transmission cycle in the village came
from a variety of sources. Socio-economic data were gathered through my survey that
covered 251 households, or 77 percent of the total number of households in the village.
The survey covered the following factors: demographic characteristics, living conditions,
livelihood, income and expenditure, the animal population, water contact behavior, knowl-
edge of schistosomiasis, attitudes toward schistosomiasis, control measures and the con-
trol program, degree of community participation, and health-seeking behavior. In addi-
tion, environmental data were gathered through direct field observations, map measure-
ments, airphoto interpretation, and from published sources. Parasitological data and direct
quantitative observations of actual water contact were furnished by the Research Institute

of Tropical Medicine, Department of Health, Republic of the Philippines.

Medical geography offers an excellent springboard from which to launch integra-
tive investigations of parasitic diseases, including schistosomiasis. There are many excel-
lent examples, which do not need elaboration here (Hunter, 1966; 1972: 1981a; 1981b;
1992; Meade, 1976; Kloos, 1985; Fonaroff, 1968). By adopting a geographic perspective,
it may be argued that the level of endemicity of schistosomiasis in an area is determined by
the character of the place, which is seldom the result of any single physical factor. Rather,
such endemicity is determined by the interaction of a number of social, economic, cultural

and physical phenomena.

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CHAPTER 2

REVIEW OF RELATED LITERATURE

This chapter will review the current state of knowledge regarding schistosomiasis
japonicum transmission and control in the Philippines. The characteristics of and linkages
'among the elements of the transmission system will be explored. Through examples, it
will show the relationship between schistosomiasis transmission and the environment. The
significance of water contact behavior and its consequences on morbidity and mortality
will be examined. Finally, it will look at the different methods that have been applied in

the Philippines for limiting schistosomiasis transmission.

The occurrence of schistosomiasis japonicum in the Philippines was first reported
in 1906. Subsequent reports published in 1908 based on autopsy records of a patient in
the Philippine General Hospital and fecal examinations of 4,106 prisoners in the National
Penitentiary in Manila indicated that the disease may be endemic in the southern parts of
the Philippines, particularly in the islands of Leyte, Samar, and Mindanao. The snail in-
termediate host, Oncomelania quadrasi, was first described using specimens from Surigao
province in Mindanao. Its role as a snail intermediate host of schistosomiasis japonicum
was first recognized in 1932 based on observations made at Palo, Leyte (Schistosomiasis

Control Service, 1987).
The Parasite

Only one strain of S. japonicum exists in the Philippines (Garcia, 1976). Strains
recovered from naturally infected dogs, pigs, carabaos, cows, goats, rats, and monkeys are
morphologically indistinguishable from strains of human origin. This suggests that the

control of schistosomiasis should involve more than the attack on the parasite through

12

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sanitation and treatment of the human host; it should also take into account the relative

role in transmission played by animal hosts of S. japonicum.

Schistosoma japonicum is generally considered as the most virulent of the three
human species of blood flukes because it produces a larger number of eggs than the other
two species. In Leyte, Philippines, a study of egg-laying potential of S. japonicum in mice
has shown that eggs are laid in clusters and that the female worm lays 116 eggs each time,
12 times daily (Pesigan et al., 1958a). The eggs require relatively clean freshwater with
sufficient oxygen to hatch. The eggs that have been excreted out of the host are able to
survive for up to one week, especially if they have been deposited in the shade. This
implies that in schistosomiasis endemic areas in the Philippines where rainfall is distributed

evenly throughout the year, the chances of eggs being washed into streams is high.

Observations of cercarial shedding of infected Oncomelania quadrasi snails re-
vealed that the average period from miracidial penetration to shedding of cercariae from
the snail is 64 days. The average shedding period is 66 days, with each snail producing a
total of 279 cercariae on the average (Hunter, Ingalls, and Greene, 1947). Studies also
show that due to the twin factors of duration and intensity of exposure to light, the
swarming of cercariae from the snail is highest between 2:00 pm and 4:00 pm.. The great-
est danger of infection to humans starts at dusk when 80 percent of cercaria have been

shed, and continues until midnight (Pesigan et al., 1958a).

There are biological and environmental limitations on the life of cercariae. Their
food reserves are exhausted within 48 hours after leaving the snail. They will die unless
they find a suitable host within this period. A salt content of greater than 3 percent leads
to cercarial death. The cercariae will survive for 2.5 days in water at 20°C to 35°C; for 4
hours at 40°C; and for only 3 minutes at 50°C (Jones and Brady, 1947). This implies that
cercariae living in shallow waters which are exposed to sunlight and therefore high tem-

peratures have only a very short period within which to infect the final host. This is the

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14

situation in inundated rice fields prior to planting. At later stages of rice growth, the rice
shoots increasingly offer shade and thus moderate the increase of temperatures due to ex-

posure to the sun.
The Snail Intermediate Host

Newly-hatched snails go through a 2-week aquatic stage before starting on an am-
phibian existence (Abbot, 1946). Within 180 days, males grow to a final size of 4.5 mm;
females grow to a larger size of 5 mm. Sexual maturity is attained at a much earlier stage:
copulation was first observed in snails of a length of 2.5 mm among males and 3 mm
among females, respectively (Pesigan, Hairtston, Jauregui, Garcia, Santos, Santos, and

Besa, 1958b). The mean life span of 0. quadrasi was determined to be 25-35 weeks.

The vertical and horizontal distribution of 0. quadrasi within the habitat is much
affected by the depth of water, light intensity, the flow velocity, the steepness of the bank,
and the plant cover. 0. quadrasi is distributed neither evenly nor randomly over its habi-
tats. Pesigan, et al. (1958b) made a study concerning the factors influencing the distribu-
tion within a colony. That study showed that snails were most numerous near the banks
and their density seemed related inversely to light intensity and depth of water. These ob-
servations were made in mid-moming, from 9:00-1 1 :00 in clear weather. A later study
made by Tanaka, Santos, Matsuda, Hambre, Iwanaga, Shirnomura, Blas, and Santos
(1978) showed that in general most of the snails remain in the immediate vicinity of the
banks. On the basis of investigations of a wide variety of water types, they arrived at the
conclusion that “. . . 0. quadrasi is determined not to be aquatic in habitual character than

was presumed before . . ." (p. 193).

Snail colonies investigated in the Philippines showed a very marked locational con-
stancy; 0. quadrasi is able to persist for decades in a suitable habitat. As described by
Pesigan et al., ( 1958b), the most important types of places that harbor the snail may be

grouped in several categories: (1) flood-plain forest and swamps that represent the most

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extensive original habitat of the snail; (2) ricefields where small holding agriculture is
being practiced; (3) streams which are meandering and sluggish; (4) small water pockets
located at the foot of high and steep banks that are fed by seepages and springs emerging
below the banks; and (5) road ditches and borrow-pits that arise from the construction of

roads in lowland areas.

The distribution of 0. quadrasi as an arnphibiously living snail is primarily deter-
mined by climatic conditions. Its sensitivity to aridity restricts its distribution range to
those two climatic zones which receive precipitation throughout the year, and this in turn

defines the potential area of schistosomiasis distribution in the Philippines (Santos, 1976).

The maximum flow velocity of waters that 0. quadrasi can tolerate is about 20 m
per minute (Hinz, 1985). The factors that influence the velocity of water flow are terrain,
the distribution and quantity of precipitation, the land and water vegetation and the course
followed by the waters themselves. Steep slopes cause the flow velocity to exceed the
tolerance limit of 0. quadrasi, especially during the aquatic phase of the young snails. For
this reason, neither snails nor schistosomiasis are to be found in the hills or mountains of
the Philippines. Thus, 0. quadrasi habitats are characterized by their flatness (Pesigan et
al., 1958b). Ample vegetation growth in waters can significantly reduce their flow veloci-
ties such that habitats suitable for snails are created. A precipitation regime that is constant
throughout the year results in nearly constant water levels, which result in minor fluctua-

tions in water velocity.

The nature of the water is significant for the occurrence of 0. quadrasi. Heavily
salinated areas in the coastal lowlands are unsuited as snail habitats because the snail can
only tolerate fluctuations of 10-430 p.p.m. Water temperatures of between 23-30°C are
favorable for snail habitats (Pesigan et al., 1958b). As far as the pH value of the water is
concerned, the optimum for 0. quadrasi lies in the slightly alkaline range at pH 7.4 -7.6
(Hunter, 1950).

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Animal Reservoirs

A variety of mammal species contribute to the persistence of schistosomiasis. The
extent of their contribution to the process of transmission varies from one species to the
next, however, and for every species from one area to the another. Pesigan et al. (1958a)
found several animals acting as reservoir hosts of S chistosoma japonicum in Leyte, Phil-
ippines such as the dog, pig, carabao, cow, goat, and rat. Their studies showed that the
cow had the highest prevalence (38.2%), followed by rat (22.7%), and dog (18.2%). The
transmission index for each host was calculated by multiplying the factors of population,
prevalence, mean daily egg output, and hatchability. Subsequently, they computed the
relative transmission index for each host, which is expressed as the percentage of the total
role played by all the hosts involved. They found the dog to be the most important reser~
voir host of Schistosoma japonicum in that area based on a high relative transmission in-
dex of 14.4% next to 75.7% index for humans. Cows, pigs, and rats had relative
transmission indices of 5.7%, 1.5%, and 1.5%, respectively. A more recent study
(Fernandez, Petilla, and Banez, 1983) highlighted the important role of the dog in
maintaining the transmission cycle of Schistosoma japonicum in endemic areas due to its
high transmission index. This role is enhanced by the fact that in areas where the study
was conducted, these animals are regarded as pets and live for years in close contact with
people.

Several recent studies have stressed the importance of the role of the field rat in
maintaining schistosomiasis transmission. Hinz (1985) concluded that on the basis of re-
sults arrived at in Leyte, the greatest significance next to humans attaches to the field rats
(Rattus rattus mindanenis) because of the numbers of its individuals, its way of life, and its
high prevalence rates. Cabrera (1976) pointed out that the rapidity by which field rats
multiply and the fact that they obtain their food from the ricefields plus their habit of defe-

cating several times in 24 hours should all be taken into consideration when one tries to

17

assess the role played by them in the dissemination of the infection in nature. His study of
Schistosoma japonicum in field rats in Leyte, Philippines showed that approximately 73%
of the wild caught field rats were found infected with Schistosoma japonicum as revealed
by the findings of eggs in liver sections. The infection among field rats was highest in ar-
eas where no control measures were applied. Transmission of the disease in these areas is
high possibly because there are more infected snails shedding cercaria in irrigation ditches

and other water collection areas in the ricefields.

Seasonal fluctuations of prevalence rates in rats have been observed. They at-
tained their highest values (95%) during the months of lower precipitation frequency
(April to July), as opposed to an average of 76% during the remainder of the year. Mean-
while, the prevalence rate of schistosome cercariae in the snail increased during the rela-
tively rainy season, October to February. Thus, it is suspected that miracidia hatched from
eggs discharged from the feces of rats during April to July and, subsequently, the snails
were infected with miracidia. It is also supposed that the cercaria which emerged from the
snails might penetrate mammalian hosts during the rainy season, October to February
(Kamiya, Tada, Matsuda, Blas, Noser‘ias, and Santos, 1980). This implies that the inhabi-
tants in endemic areas of Leyte island were frequently exposed to cercariae during the
rainy season. These observations also indicate that field rats not only maintain the infec-
tion as reservoir hosts, but are also an important source of infection as definitive hosts in
the endemic areas of Leyte island. Control programs must take into account the role of

the rat in schistosomiasis transmission.
Human Pathology

Schistosomiasis japonicum is a disease that has a variety of symptoms. The early
and acute phases cover the period from the time of cercarial penetration to the oviposition
of the mature female worm which is approximately 40 days. Cercariae, the infective lar-

vae, gain entry by penetrating the skin. Cercariae successfully breaking through the skin

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18

undergo a period of migration and development which may give rise to a symptom-com-
plex consisting of irregular fever, headache, stiff neck, malaise, anorexia, weight loss, ab-
dominal cramps, muscle and joint pains, constipation or diarrhea, and cough or puhnonary
involvement. During this phase, a majority of immune persons (70-80%) may be either
mildly or moderately ill while the rest may be severely ill or asymptomatic. Among natives
of endemic areas, this is generally less severe or may not be present at all especially in

those having light infections (Olveda and Domingo, 1987).

The maturation of the worm with the onset of oviposition from a minimum of 30
days or longer after exposure paves the way for the acute or toxaemic case. This serum
sickness-like stage commonly known as Katayama fever is marked by prominent eosino-
philia which mainly accounts for the high level of leukocytosis arising from the absorption
of worm metabolic products. Diarrhea or dysentery with bloody mucoid stools is seen in
25%, which at this stage is usually referable to colonic involvement. If the patient is left
unheated, the disease may enter the third or chronic stage as early as three months after
exposure. The early or chronic stage may be accompanied by temporary remission of
acute signs and symptoms in some individuals. In endemic areas, some infected residents
may start presenting a palpable liver or spleen in the third month after exposure. The
more common forms of chronic schistosomiasis japonicum are hepatosplenic and intesti-
nal; in some instances pulmonary and cerebral forms may be seen. One form may overlap
another at any stage of infection presenting an unusual symptom complex. (Olveda and

Domingo, 1987).

The complications that have been observed consist of extension of the lesions from
the abdominal viscera to other tissues and organs of the body, and secondary infections or
disease processes. Among these are: (a) neurological manifestations, which are frequently
of the J acksonian type of epilepsy demonstrated to be caused by the lodgement of S. ja-

ponicum eggs in the brain; (b) hematemesis (blood loss) resulting from the rupture of

19

esophageal and gastric varices; (c) cor pulmonale characterized by enlargement of the

right ventricle due to increased pressure in the pulmonary circulation caused by

pathological changes in the pulmonary arteries or massive embolism where schistosomes

are involved; ((1) hepatic cirrhosis with or without splenomegaly may supervene; (e)

supervening diseases, which may consist of chronic processes from which the patient may

suffer like tuberculosis, malaria, deficiency diseases and acute infectious diseases such as

pneumonia and infectious hepatitis (Schistosomiasis Control Service, 1987).

The following is a conventional classification of schistosomiasis cases based on the

pathogenesis of the disease (Schistosomiasis Control Service, 1987).

 

Stage and Important Features

 

Pre-Egg Deposition Stage (not. usually seen): With urticaria] rashes, itchiness, localized
dermatitis, cough, angioneurotic edema, fever and other allergic manifestations. May have
diarrhea.

 

Early Egg-Deposition with Early Hepatic Irrigation: With bloody mucoid stools or diarrheic
attacks of recent onset. Liver may be felt on deep inspiration, with slight tenderness toward the
right of the epigastrium. Spleen not yet palpable. Duration of this stage -- 5th week from date
of exposure to one year or even earlier depending on the heaviness and severity of the infection.

 

Late Egg-Deposition with Definite Liver Enlargement (Pre-cirrhotic stage): May have
recurrences of diarrhea or dysentery-like symptoms. Abdominal and right hypochondriac pains
increased. Liver enlargement marked especially below xiphoid process. Spleen only slightly
enlarged. Duration of this stage -- 1 to 1.5 years from date of exposure.

 

Frank Cirrhosis: Size of liver receding but still palpable. Spleen markedly enlarged. Superficial
abdominal veins visible. Ascites beginning. Emaciation is visible especially in undemourished
individual. Patient may die of severe hemorrhage due to rupture of oesophagial varices.
Duration of this stage -- 2nd year onwards.

 

 

 

Advanced Cirrhosis with marked emaciation. Very marked splenomegaly, liver small and
contracted or non-palpable. Distinct ascites and very prominent superficial veins. Emaciatiou
and anemia marked.

 

Diagnostic and laboratory methods to prove schistosomiasis infection can be para-

sitological or immunological. Parasitological techniques are necessary for providing a de-

finitive diagnosis of an active infection: schistosome ova are demonstrated in urine or

 

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stools, less frequently in tissues; rarely, diagnosis may be made by finding adult worms in
the histological sections. Immunological techniques include the WHO reference skin test,
(Melcher's antigen), Complement fixation test, circumoval precipitin test (COP), fluores—

cent antibody test (FAT), ELISA (enzyme-linked immunosorbent assay), and RAI (radio-

irnmunoassay) (Jordan, 1982).

Schistosomiasis lacks the impact that some tropical diseases deliver to affected
populations. This is because it provides a case of successful parasitism: the parasite relies
on co-existence rather than elimination of the human host. Previous studies in Palo, Leyte
have shown that only 37.8 percent of schistosome-infected individuals were symptomatic
and that the prevalence of infection reaches its peak in the age group 20-24 years. High
prevalence and intensity of infection have been noted in women between 45 and 55 years
old. The most vulnerable group are children aged 10-14 wherein 73% of those infected
manifest symptoms related to schistosomiasis. It has been observed that although preva-
lence remains high, egg output gradually decreases after the age of 20 (Schistosomiasis

Control Service, 1987).

A growing tolerance of the infection appears to suppress clinical manifestations,
and acute attacks become infrequent once the individuals get past the most vulnerable age.
Infection among adults therefore is not synonymous with the disease. This can only be
explained on the basis of immunity, which causes the destruction of schistosomules during
migration, developing as a result of constant exposure to schistosome infection from early
life. Schistosomiasis is claimed to be an immunological disease due to granulomatous hy-
persensitivity to parasite eggs. Different degrees of immunity have been considered: in-
nate immunity (i.e. that only a relatively small proportion of an infecting inoculum of cer-
cariae will develop into adult worms), the possible occurrence of non-specific immunity
(e.g. in patients with tuberculosis), the development of only partial degrees of specific im-

munity (as demonstrated in many experimental animals), and the occurrence of

21

irnmunoregulatory phenomena that supress immunopathology and hence disease (Warren,
1982). It has been observed that the egg counts of people in age groups past the age of
peak prevalence are notably less than those of younger people. Studies show that the
majority of infected persons excrete low numbers of eggs and the patterns of prevalence

and/or intensity is bimodal (Jordan and Webbe, 1982; Hairston, 1973).

Human behavior is exceptionally important in the transmission of schistosomiasis.
Agriculture may have the effect of reducing snail populations through control of streams,
drainage and proper cultivation, but it may also bring about great increases, especially
through the requirement of irrigation, and also through certain improper practices, such as
permitting the land to become waterlogged and inadequate cultivation. Human contact
with water increases in rural farming populations and also increases directly with tempera-
ture (Hairston, 1973). Some activities involve contact with water for long periods; other
activities may only be brief and unintended. These activities include plowing, weeding of
rice fields, washing clothes, bathing, swimming, obtaining water, and wading across rivers,

irrigation canals, and snail habitats.

The endemic areas of schistosomiasis in the Philippines (Figure 2.1) were identified
through a series of studies and mass surveys. These endemic areas lie between 6° and 14°
North latitude in the provinces of Mindoro Oriental and Sorsogon in Southern Luzon; the
provinces of Northern, Eastern, and Western Samar, Leyte, and Bohol in Eastern Visayas,
and all the provinces of Mindanao except Misamis Occidental, Davao Oriental and
Maguindanao. In these areas, there is no pronounced dry season. Of the four climatic
types present in the Philippines, all endemic areas fall under Type II and IV, both of which
are characterized by the absence of a dry season. Type II has a pronounced maximum rain
period from November to January while Type IV has no pronounced maximum rain pe-

riod. Types I and III have distinct dry seasons (Blas, Bautista, and Lipayon, 1990).

 

1L

22

Schistosomiasis; udem

 

Figure 2.1 Schistosomiasis-Endemic Provinces of the Philippines. Source: Author's
figure; data from Blas, Bautista, and Lipayon, 1990.

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The climatic and terrain limitations of the snail intermediate host open possibilities
for a prediction system that would locate potential schistosomiasis-endemic areas that may
contain unregistered small irrigation systems. Cross (1984) conducted a study as part of a
project whose objective was to take a limited quantity of point or local data for a disease,
and transforming this to a prediction system that would provide disease occurrence prob—
abilities throughout an entire region. As conceived, the model would utilize available
geographic, topographic, and climatic variables and whatever limited disease data may be
available; it would operate without an explicit biological model, since many of the envi-
ronmental variables necessary for the development of disease foci are available only for
small, restricted study areas; and it would be statistical in nature, since the relationship be-
tween the disease occurrence and the geographical variable must be established via statis-

tical correlations.

Cross developed discriminant analysis models to describe the known distribution of
schistosomiasis in the Caribbean and the Philippines in terms of summary variables of
monthly mean values of precipitation and temperature. Although the results were good,
there were some recognized problems: (1) disease site information was geographically co-
located to a weather station which, in some cases, was located a few miles from the actual
disease site, and which could have caused some inaccuracy in the analysis; (2) of the 157
weather stations in the Philippines, only 27 were in areas where schistosomiasis occurred,
and (3) some of the misclassified observations were in areas where terrain features, i.e.,
location near a lake, areas with a steep gradient causing rapidly flowing streams, etc.,
which had the ability to modify the results. These problems were rectified by
incorporating an interpolation procedure to compute the weather variables at the actual
disease sites, and by using remotely sensed data from Landsat spacecraft to provide
information for the geographic variables. Incorporating Landsat data into the system

provided some geographic information, as well as permitting the extension of point data to

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an entire area. Thus, a disease distribution map can easily be produced, based on the
statistical correlation between disease occurrence and geographical variables and the

accuracy of prediction assessed visually.

People living in endemic areas are generally aware of the schistosomiasis problem.
However, Tiglao (1979) showed that there are gaps regarding their knowledge of how the
disease is transmitted and controlled. Although people knew that schistosomiasis is ac-
quired through water contact, for lack of convenient options, they continued to frequent
potentially infected bodies of water. The role of the snail intermediate host in the
transmission of the disease was not generally known. Toilets, even if in existence, are not
utilized. None of the respondents in the study knew that animals such as dogs and pigs
can act as reservoir hosts of schistosomiasis. The study indicates that knowledge of
schistosomiasis transmission and control is affected by sex, age, educational attainment,
occupation, and experience with the disease. Those who are less knowledgeable about the
disease are usually females, the younger and older age group, those with low educational
attainment and economic status, laborers, and those who have not had any experience with
the disease. Among the factors that influence disease awareness, age, educational
attainment, and economic class exert significant influence on the attitude towards
elimination of the snails. The factors that influence attitudes towards willingness to
participate in a snail campaign are age, prevalence of the disease, and experience with the
disease.

As revealed in a follow-up study (1‘ iglao and Camacho, 1983), the prevalence rate
of schistosomiasis was 55% in two villages, with males having a higher prevalence rate
than females. The study showed that three variables have significant relationships with
intensity of infection, namely: economic activities, gender, and bathing. This means that
males tend to have a higher infection than females; economic activities, particularly

washing farm animals and bathing, are likely to produce heavy infection. This may be

25

explained by the fact that the data show that males have longer duration of exposure than
females; that their economic water contact activities tended to be twice as long as their
other non-economic activities and that the economically active age groups had the higher
mean duration of water contact. When the water contact activities of the positive and
negative cases were compared, it was noted that the activities that really discriminate be-
tween the two groups were washing farm animals, washing farm tools and equipment and
ditch tending. People continued to frequent the infected waterways despite being aware of
the risk of infection because they were forced to for economic reasons. The study
concluded by stressing that provision of an adequate source of drinking water and public
baths and laundry areas are of paramount importance in the control of schistosomiasis.
However, providing such water sources should take cognizance of the psycho-social
factors attendant to the use of the waterways. It also recommends the implementation of
an educational program to: (1) encourage better waste disposal through the construction
and proper utilization of sanitary toilets and, (2) create the correct perceptions about the
cause, transmission and control of the disease. Finally, the study recommends that greater

effort should be directed towards reaching the males and economically active age groups.

To fill a gap on the epidemiology and morbidity of S. japonicum in the Philippines,
Lewert, Yogore Jr., and Blas ( 1979) chose Barrio San Antonio, a coastal settlement on
the San Juanico straits in the municipality of Basey on the island of Samar, the Philippines.
Although some individuals of Barrio San Antonio have sought therapy, this population
and area have been largely unstudied and have not up to the time of the study been in-
volved in control or mass chemotherapy programs. The village has a population of ap-
proximately 1,900 in 320 households. Rice farming is the primary occupation. There is an
annual rainfall of about 250 cm with 220 rainy days. The endemicity of S. japonicum in
the municipality of Basey was established in surveys in 1951. Infected Oncomelania

quadrasi were also demonstrated. Initially, 851 residents (45%) of 240 households

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26

participated in the survey to determine the prevalence and intensity of Schistosoma japoni-
cum infection, and morbidity as indicated by associated hepatomegaly and splenomegaly.
As a result of an initial single stool examination of 1 ml by a modified formalin concentra-
tion technique, 40% of this population was found to be infected. On subsequent examina-
tions, with the addition of serologic techniques and recording the history of therapy, ap-
proximately 70% of this population was found to be infected with S. japonicum after the
age of 10 years. If judged by the number of eggs produced per milliliter of feces, infection
intensity in this population might be considered to be low. However, 25% (73 of 391
positives on single examination) exhibited schistosomal hepatomegaly or hepato-sple-
nomegaly and had a mean egg count of 10.9. Those infected but without hepatomegaly
had a slightly lower mean egg count of 8.4. Of the infected males with hepatomegaly,
75% were 19 years of age or less, and 45% of these were producing less than 10 eggs/m1
of stool. Of infected females with hepatomegaly, only 28% were 19 years of age or less,
and 68% of these were producing less than 10 eggs/ml. of stool. Abdominal pain, distress,
diarrhea, and dysentery were significantly more frequent in the infected than uninfected
persons, and this frequency was related to egg output. The heights and weights of these
infected individuals were less than those of the uninfected members of this population and
significantly less than the Filipino norm. The small percentage of the infected population
(6.6%) that were producing 51% of the eggs had a mean egg count of approximately 260
with a mean age of 33.7. In this group, 7 of the 22 individuals were in the age group 10-
14 years and 15 were above 20 years of age. The findings of this survey give an opportu-

nity to determine the impact of control programs when they are instituted in this area.

An investigation covering two villages in Irosin, Sorsogon province showed that
the overall prevalence of Schistosoma japonicum infection was 49.5% in a total study
population of 755 persons. The peak prevalence rate of 70.2% and the highest egg counts

were found in the 15-19 age group. The prevalence and intensity of infection were higher

LI

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27

in men than in women except in the 45-54-year age group. A small proportion (4.1%) of
the study population (age range 6-53 years) excreted 50% of the eggs counted in the
study. However, individuals with high egg counts were found in other age groups. Thus,
the study stresses that although contamination of the environment is due to a small number
of highly infected persons, chemotherapy directed at a specific age group could not be
expected to reduce significantly the total number of eggs excreted, or to have an impact
upon morbidity related to high intensity infections. Liver and spleen enlargement were
significantly associated with S. japonicum infection in all age groups. The frequency of a
past history of dysentery and marked liver enlargement increased in parallel with in-
creasing egg counts. Clustering of individuals with high egg counts in households was
observed, but there was no correlation between geographical proximity of residence to
potential transmission sites and household infection rates. An effective control strategy
would be based on treatment of all infected persons in this endemic area rather than only a

selected age group (WHO Workshop, 1980).

In the rice farming village of Santa Rosa, Leyte, Domingo, Tiu, Peters, Warren,
Mahmoud, and Houser (1980) observed that there was no relationship between sple-
nomegaly and the presence or intensity of infection. Like the Irosin study, a peak preva-
lence was noted in the 15-19 age group of this village. Of the 1,098 individuals who were
examined, 32.4% were found infected with S. japonicum. Of these, 21% bad light infec-
tions (1-100 eggs/g feces), 8% had moderate infections (101-400), and 3% had heavy in-
fections (>400). The mean egg count for the entire population (uninfected and infected)
was 50 eggs/g, males averaging 73 and females 27. The mean egg count for the infected
population was 154 eggs/g; that for infected males was 186 and infected females 105. The
intensity of infection in males peaked at age 15-19 (256 eggs/g) and in females 25-29 (253
eggs/g). The study revealed that in comparison with an uninfected control group in the

same community there was no impairment in activity, no increased incidence of colicky

28

abdominal pain and no increase in the number of stools per day, in their consistency nor in
the presence of blood in the feces. The investigators concluded that S. japonicum infec-
tion of a moderate prevalence and intensity was associated with low morbidity. They fur-
ther observed that schistosomiasis japonicum did not appear to be a significantly more

pathogenic infection than schistosomiasis mansoni.

An expanded study on the relationship between intensity of infection and morbidity
was conducted by Olveda, Tiu, Fevidal, De Veyra, and Domingo (1983) in three Philip-
pine villages with differing prevalences of infection. Due to a flat to nearly flat topography
and an even distribution of rainfall throughout the year, rice is grown in the three villages.
The sources of water for domestic use are mostly open dug wells, although some house-

_ holds are equipped with hand pumps. Water sealed toilets are available for half the popu-
lation but are rarely used because of the difficulty of obtaining water for domestic use.
Almost all inhabitants are farmers, and agricultural activities are carried out all year round.
Prevalences of 26%, 39%, and 44% were found in the three villages. A majority of their
populations (56-74%) were not infected. Within the total population, 17-30% had light
infections, 7-l4% had moderate infection, and only 2-7% had heavy infections. Symp-
toms of inability to work, weakness, abdominal pain, and diarrhea correlated with the
presence of infection in the area with the highest prevalence, but not in the area with the
lowest prevalence. Except for diarrhea, there was no relationship between symptoms and
intensity of infection. This study showed that there was no significant association between
area prevalence and intensity of infection. Age prevalence and egg excretion peaked ear-

lier in areas with higher prevalence than in the area with lowest prevalence.

Because schistosomiasis is an example of successful parasitism, deaths due to the
disease alone are relatively low and often difficult to ascertain. Blas, Cabrera, Santos, and
Nosei'ras (1986) conducted a study to gather data that can serve as a basis for computing

the economic burden imposed by deaths due to schistosomiasis. The study is a response

29

to the dearth and unreliability of data on the number of deaths from schistosomiasis. This
state of affairs was caused by the refusal of the relatives of dead patients to give permis-
sion to have the abdomen punctured with a viscerectomy instrument. To remedy this
situation, the authors thought of following up on a cross-sectional study on the clinical
gradient of schistosomiasis that was conducted 12 years earlier in connection with the
Schistosomiasis Control Pilot Project in Palo, Leyte, Philippines. At the start of the proj-
ect, 48% of the population was found positive for Schistosoma japonicum eggs in their
stools. From the positive cases, a 20% stratified sample consisting of 278 individuals in
the different zones of Palo were examined and followed up periodically. All the 278 cases
previously found positive for S. japonicum eggs in their stools were included in the fol-
low-up study. However, only 154 cases including those who died could be located be-
cause the rest had migrated to other places. Of the 154 cases followed up, 19 were treated
with schistosomicidal drugs and were therefore excluded in the analysis. Of the remaining
135, a total of 23 (17.04%) died from various causes of which 12 (8.89%) had signs and
symptoms attributable to schistosomiasis as the immediate cause or one of the main causes
of death. Among the surviving cases, only 25% remained symptomatic compared to
54.5% 12 years earlier. The case fatality rate of 8.89% in a span of l to 11 years, which
corresponds roughly to 1.78% of the infected cases per year, is considered as a conserva-
tive estimate because in other deaths due to other diseases, schistosomiasis is a contribu-

tory cause.

Snail Control

The studies of Pesigan, et al. (1958b) regarding potential repopulation of snail
colonies paved the way for the evaluation of subsequent snail control measures. Their

findings showed that young snails, especially those in the aquatic stage, are most

Strep

1011110

01‘ 5.

E1110

30

susceptible to any sort of control measure and that most or all of the survivors after

control will be adult snails. They concluded that:

. . . any method, such as the use of molluscicides, that leaves the habitat suitable for
repopulation will have to be repeated at frequent intervals. . . . the chemical would
need to be applied before the peak of the first generation of the young, or at intervals
of 120 days -- three times a year.

. . . prevention of breeding is more important than success in killing the snails that
are present. The potential for repopulation can only be attacked through radical re-
population of the habitat, making further breeding impossible or reducing it to the
point where it does not keep pace with normal mortality rates. . . . (p. 344).

The discovery of new snail habitats and area-wide mollusciciding were the con-
cerns of the study conducted by Yasuraoka, Santos, Blas, Tanaka, Matsuda, Irie, Shi-
momura, and Pangilinan (1989) in the municipalities of Trinidad and Talibon, Bohol Is-
land, Philippines. The endemic focus of schistosomiasis on the island is confined only to
the left bank of Ipil River or to two of the 46 municipalities of the island, namely, Talibon
and Trinidad. The study team succeeded in locating seven new snail populations between
1985 and 1987. The team was led by the proximity of the snail habitat to the residence of
the infected individuals. In addition they often used palawan plants (Cryptosperma
merkusii), a relative of taro, as an indicator of snail habitats. This plant can grow only in
very wet ground and provides an excellent shade and enough moisture for snails to thrive.
0. quadrasi was found less resistant to dryness than 0. nosophora, the intermediate host
of S. japonicum in Japan. 0. quadrasi seldom, if ever, survived longer than three weeks
under relative humidities ranging from 60 to 85 percent at temperatures of 24 to 27°C,
while they could survive at least three months in a moist environment (99 to 100% relative
humidity). The continuous wet condition in Northern Bohol appeared to make the major
difference between places that do and those that do not support the snails. Mollusciciding
activities involved twice yearly clearing of vegetation by mowers and rakes and applying
chemical molluscicides (niclosamide and phebrol) manually by uniform spraying at a rate
of 5-10 grams per square meter. The study revealed that although combined vegetation

removal and chemical mollusciciding appeared successful in eliminating and reducing the

snail 1
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31

snail population in most of the swamps, it did not yield satisfactory results in meandering
streams. Ecological or engineering measures such as cement-lining could be expected to

limit or reduce the snail populations.

Makiya, Tanaka, Banez, Blas, and Santos (1986) chose to control snail popula-
tions through environmental modification such as clearing of vegetation, reclamation of
swampy land, draining water by channeling and excavation. About 50 snail populations
were surveyed at 18 sites in 3 project areas, i.e., Dagami (4.3 hectares), Matagob (0.5 ha.)
and Tacloban (2.2 ha.) in Leyte, Philippines, from 1974 through 1977. They made a
quantitative evaluation to measure the change of snail density as the effect of control
measures in the project areas that were based on theoretical principles derived from previ-
ous snail population studies. Environmental modification included clearing of heavy
vegetation, leveling of swampy depression and drainage of stagnant water in the
waterlogged areas by heavy equipment. Channeling and excavation of water pathways
were performed by manual works to improve the water flow in ditches, streams, and
abandoned areas around the rice fields. Reclaimed areas were maintained by human labor
every 3 months or from time to time depending upon the conditions of water flowing.
Density reduction was observed at 13 of 18 sites with reduction rates from 10.5 to 100%
at the survey in the final year, and significant reduction was confirmed at 9 sites. The
structure of the snail population changed from a distribution of colonies (clusters of snails)
into a distribution of individual snails with the decrease of soil moisture and snail density.
It was concluded that drainage work is an effective and long-lasting control measure
against snail populations if the drainage canals are well-maintained and functioning
properly. The snail distribution, following the double Poisson or Neyman Type A
distribution at first, became fitted better to the negative binomial distribution in the later
years in most sites. From the theoretical analysis of distribution types, it seemed that the

types of distribution changed from a colonial distribution into that of individual snails

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32

without forming clusters as the population density decreased. The study concluded that
there is no doubt that the snail population can be reduced by physical environmental
modifications. For effective control of schistosomiasis japonicum by means of snail
control, a large scale plan of land reclamation together with persisting maintenance of

reclaimed areas is necessary.

Proper water management and sound agricultural practices to attack and eradicate
the snail as the intermediate host of the parasite was the approach used by Santos, Blas,
Redona, and Santos (1970). An agricultural demonstration area was put up in Sitio
Mayaot, Barrio Malirong, Palo, Leyte, Philippines to demonstrate ways of increasing rice
yield while at the same time controlling the snails transmitting schistosomiasis. The area
selected consists of 2.95 hectares which used to be part of a water-logged area overgrown
with thick vegetation. This snail-infested area was initially drained by an intercepting and
a main drainage canal. Subsequently, the reclaimed area was diked and subdivided into
paddies. Finally, irrigation pipelines from the irrigation canal to the diked paddies and a
system irrigation, drainage, and intercepting canals were installed. With the land
preparation completed, two rice crops were planted on successive planting seasons. Snail
densities before, during and after planting were obtained. An adjacent area which
remained fallow throughout the experiment and wherein snail densities were similarly
gathered served as the control plot. In the initial snail sampling, a baseline data of 231
snails per square meter was observed in the experimental area and 196 per sq.m. in the
comparison area. The snail density in the latter was lower, because it was relatively drier.
After the completion of the system of drainage and inigation canals, an appreciable de-
crease in the snail density to 91 per sq.m. was noted while the density in the comparison
area remained practically the same. Results of another sampling before farming and
planting revealed a further decrease to an average of 1.6 snails per sq.m. in the demon-

stration area. In the comparison area the snail density was 166 per square meter. After

33

the first harvest, another snail sampling conducted in the area gave an average of 0.7 snail
per sq. meter. A subsequent sampling done after the second harvest showed that the snails
had been totally eradicated in the demonstration area. On the other hand, an increase in
snail density was observed in the comparison area during the sampling made after the first
and second harvest The results of this study showed that a good drainage system
together with control of water supply is not only a sound agricultural practice, but also
detrimental to the snail hosting S. japonicum. Together with thorough preparation and
constant weeding, these factors led to the disruption of the ecological set-up which

prevented snail breeding.

Agro-engineering and sanitation improvement methods to control S. japonicum
were also carried out in Leyte with the assistance of the United Nations Food and Agricul-
tural Organization (Blas, 1976). The agro-engineering methods include stream channeli-
zation, seepage control, diversion and intercepting channels, canal lining, drainage and ir-
rigation schemes, combined vegetation removal and drainage, earth filling, ponding, and
improved rice culture. Sanitation improvement methods include latrine construction,

provision of safe water supply, building of foot bridges, and control of stray animals.
Chemotherapy

Praziquantel was first introduced in the Philippines for clinical trials against human
schistosomiasis in 1975. Initially, praziquantel was tested for tolerance and efficacy
against placebo in two consecutive double-blind clinical studies in Leyte using a single
dose of 50 mg/kg body weight and a total dose of 60 mg/kg body weight given in 3 di-
vided doses at 4-6 hours intervals. A subsequent trial was conducted among outpatients
to determine the toxicity and efficacy of three other dosage schemes and whether these are
influenced by such variables as age, intensity of infection as measured by egg count per
gram of stool (EPG) and intestinal parasitism. The most frequent side reaction was ab-

dominal discomfort, followed by fever, vomiting, dizziness and headache. While a single

34

dose is more convenient and advantageous, the divided dosage is necessary to minimize
the occurrence of severe side effects. The dose of 3 x 20 mg/kg body weight or a total of
60 mg/kg body weight seemed to be the optimum dosage scheme in terms of efficacy and
minimum severe side effects. The results of the trials showed that a dosage of 2 x 20
mg/kg was suitable and practical for large scale field treatment after treating over 1000
patients without encountering any severe side effect (Noser‘ias, Santos, Blas, Tormis,

Portillo, Poliquit, Papasin, and Flores, 1984).

The use of chemotherapy on cerebral and hepatosplenomegalic forms of schistos-
omiasis were the subject of two separate studies in Leyte. Hayashi, Matsuda, Tormis,
Noser‘ias and Blas (1984) conducted a follow-up study of the 127 cases of cerebral schis-
tosomiasis that had been treated with antischistosomal drugs at Palo, Leyte, Philippines
since 1975. Clinical changes of the brain before and after the treatment with antischis-
tosomal drugs were studied by close neurological examination, electroencephalography
and computer tomography. Cerebral schistosomiasis was selected by parasitological find-
ing and by excluding clinically, vascular disorder of the brain, brain tumor, genuine epi-
lepsy, and trauma of the brain. Before treatment, 64 or 91% experienced a high frequency
of seizures no less than once a month. After treatment, the seizure disappeared in 53, be-
came 50% less frequent in 13, the frequency did not change in 2, but was increased in 2
cases. Overall, the effective cure was observed in 66 out of 70 (94%). The study com-
pared the curative effects of stibophen, niridazole, and praziquantel based on results of
parasitological examination. Before 1977, stibophen and niridazole had been utilized.
Among 47 cases treated with these drugs, completely cured cases were 8 with a cure rate
of 17%, transient effectiveness in their clinical course was in 2, and non-effective in the
rest of the cases. After 1977, 49 patients were treated with praziquantel at a total dose 50
to 60 mg per kg of body weight in a day. Thirty-four out of them were treated with

praziquantel because of non-effectiveness after treatment with stibophen or niridazole in

35

1975 or 1976. Complete cure was observed in 37 (75%) cases, transient cure in 5 cases.
and non-effective in 7 cases(14%). It appeared that praziquantel was more effective than

the other antischistosomal drugs.

Tanaka, Blas, Nosefias, Matsuda, Hayashi, and Santos (1985) studied the effect of
selective mass-chemotherapy with praziquantel at a dose of 60 mg/kg a day on the annual
incidence of Schistosoma japonicum on 1,800 school children enrolled at 9 primary
schools at Dagami, Leyte, Philippines. Praziquantel was given to all egg positives de-
tected not only from school children but also from the other dwellers in villages. The pa-
tients were given praziquantel at a dose of 20 mg/kg perorally 3 times in a day, at 8 am, 11
am and 2 pm, and they were cared for until 4 pm. All school children were examined for
the schistosome egg by the MIFC method of fecal examination and/or for circumoval pre-
cipitin (COP) reactions every year since 1979, except for school year (SY) 1981/1982.
The incidence of infection was utilized to evaluate the effect of control measures on schis-
tosomiasis because it is more sensitive to the change brought about by the effective con-
trol measures than the prevalence. The incidence rates before mass-chemotherapy were
22.2, 24.2, 26.9, 9.6, and 28.4% in a period from school year 1975/76 to 1979/80, re-
spectively. The low incidence in school year 1978/79 was analyzed to be caused by an
unusual drought in the previous school year, 1977/78. Egg positives including village
people were treated and the numbers treated yearly were 22, 943, 273, 300, and 341 from
school year (SY) 1978/79 to SY 1982/83, respectively. Following the start of mass-
chemotherapy, the incidence fell drastically, i.e., 8.4% in 1980-81, 6.8% in 1982-83, and
15.4% in 1983-84. This demonstrated the efficacy of mass-chemotherapy on reduction of
transmission. Thus, mass chemotherapy was proven to be effective for the control of
disease transmission and this method is considered realistic in the area where funds are
limited. Before mass-chemotherapy, a trial was made to control schistosomiasis through

environmental modification by (1) draining water, (2) improvement of irrigation canals,

36

(3) filling and, (4) leveling of wet areas in 50 ha. at the most depressed site in the project
area. Although the land reclamation planned at a large scale resulted in successful control
of schistosomiasis in Japan and China, a small scale environmental modification in this area
for some years had little effect on reduction of transmission. Moreover, available funds
were not adequate to conduct large scale public works for schistosomiasis control in most
infested areas. On the other hand, selective mass-chemotherapy needed comparatively

lesser funds than public works and resulted in drastic reduction of the incidence.

The preceding studies have shown that the physical environment imposes limita-
tions on the distribution of schistosomiasis in the Philippines and that within the suitable
environments it is the cultural habits of humans that determine whether schistosomiasis
transmission will be successful. Most of these investigations were aimed at an understand-
ing of the disease with the end in view of targeting vulnerable points in the transmission
cycle for drugs and vaccines to kill the parasite, and molluscicides to kill the snail inter-
mediate host. The dynamic relationships involving the cultural, environmental, and water
contact aspects of the disease in which humans play a major role have largely been ig-

nored.

The schistosomiasis transmission cycle, viewed from the geographic perspective,
offers an ideal framework for the analysis of the interplay between the cultural, environ-
mental, and water contact aspects of the disease. Following this framework, the remaining
chapters will describe how the interaction of physical and cultural factors makes the village
of Macanip a place where schistosomiasis transmission persists despite annual control ef-

forts of the government.

Ana

CHAPTER 3

METHODOLOGY

Analytical Framework

The key concepts of geography that give the discipline its distinct identity and co-
hesion relate to space, holism, and people-environment relationships (Hunter, 1971). The
applicability of the spatial geographical approach to the problem of schistosomiasis was
given emphasis in the recent Atlas of the Global Distribution of Schistosomiasis
(Doumenge, et al., 1987). The atlas stressed the fact that the epidemiology of schistos-
omiasis is as varied as the human ecology and environment in which it occurs. It demon-
strated the utility of the geographer’s main tool, the map, in understanding the epidemiol-

ogical diversity of schistosomiasis.

This study uses an analytical framework modeled after the transmission cycle of
the parasite that combines concepts related to space, holism, and people-environment re-
lationships (Figure 3.1). The framework reveals five subsystems of relationships that arise
from the movement of the parasitic schistosome through the different stages of its life cy-
cle in the human host, the animal host, and the amphibious snail Oncomelania quadrasi.
The five inter-related subsystems resulting from the interaction of the four factors are: (1)
the human host-snail relationship, (2) the animal host-snail relationship, (3) the snail inter-
mediate host-parasite relationship, (4) the parasite-human host relationship, and (5) the
animal-parasite relationship. The locus of these subsystems of relationships is water, the

human and animal use of which results in the convergence of the four factors of the
37

 

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38

Schistosomiasis japonicum disease system. The framework suggests that schistosomiasis '
infection persists when the life cycle of the parasite is allowed to be completed. It also

indicates the numerous opportunities to interrupt the life cycle of the parasite.

The framework shows two independent loops that represent two pathways for the
completion of the parasite’s life cycle. The first loop shows a transmission cycle that is
completed via a human host while the second shows completion via an animal reservoir.
These two cycles function independently, which implies that transmission can be main-
tained even if one of them is interrupted. This feature of the Schistosomiasis japonicum
life cycle makes the disease an anthropozoonosis. It sets it apart from other forms of hu-
man schistosomiasis that do not involve animal reservoirs. It complicates efforts to con-

trol disease transmission.

Postulated Relationships

Based on the framework that I have adopted for this study, the following postu-
lated relationship is offered: that human schistosomiasis infection in Macanip is associated
with the interaction of the following elements of the transmission cycle: hazardous human
behavior, favorable environmental characteristics, presence of intermediate host snails, and
presence of animal hosts. This broad postulated relationship may be broken down into the

following interrelated considerations:

1. The transmission of schistosomiasis is associated with favorable environ-
mental characteristics such as slow-flowing water, even distribution of

rainfall throughout the year, and shade-providing vegetation.

2. The transmission of schistosomiasis is associated with contamination of

water bodies by human feces.

39

 

Transmission and Control of Schistosomajaponicum

 

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Figure 3.1 Model of Schistosomiasis Transmission and Control. Source: Author RLC.

4o

3. The transmission of schistosomiasis is associated with agricultural practices

that favor the 0. quadrasi population.

4. The transmission of schistosomiasis is associated with hazardous water
contact behavior.
5. The persistence of schistosomiasis is associated with inadequate knowledge

about the schistosomiasis transmission cycle.

6. The persistence of schistosomiasis is associated with the inability of the

control program to interrupt the zoonotic cycle of the parasite.
7. The persistence of schistosomiasis is associated with poverty.

8. The transmission of schistosomiasis is associated with the absence of a safe

domestic water supply.

Selection of Study Area

The availability of accurate parasitological data was my main reason for the choice
of Macanip, J aro, Leyte, Philippines as the target village for this study. One of the re-
quirements of the study is an assessment of the level of schistosomiasis infection in the
study area based on accurate diagnosis. This diagnosis can be made by the Kato-Katz
method or the Circumoval Precipitin Test (COPI‘). The former involves the counting of
Schistosoma japonicum ova in human stools using a microscope while the latter involves a
blood test. Both of these methods were beyond my financial resources and academic
training. Given these limitations, I am grateful that the RITM (Research Institute of
Tropical Medicine) through its director, Dr. Remigio Olveda, gave me access to infection
data that have been gathered since the RITM started screening and treatment in Macanip
in 1982. In addition, the RITM gave me access to data representing two cycles of obser-

vations in their on-going study of human water contact in a portion of the village.

41

The RITM is one of the leading research institutions in the Philippines with a
strong record of international research cooperation. It has eight multidisciplinary research
programs addressing the following disease areas: acute respiratory infections, diarrhea]
diseases, schistosomiasis japonicum, human immunodeficiency virus infections/acquired
immunodeficiency syndrome, viral hepatitis, leprosy, malaria, and rabies. Its Schistosomi-
asis Research Program was implemented with the support of major funding institutions
like the US National Institutes of Health, the WHO Tropical Disease Research (TDR)
program, the Rockefeller Foundation, and the Edna McConnell Clark Foundation. The
research projects have for their main goals the development of a cost-effective strategy for

schistosomiasis control and the development of a vaccine against S chistosoma japonicum.

The village of Macanip is located in the municipality of Jaro, 38 kilometers west
south west of Palo, another municipality in the island of Leyte, Philippines. It is 10 kilo-
meters from the national highway. To reach it from the national highway, one has to cross
two rivers. Both bridges to these two rivers were washed out in a 1991 typhoon. During
weekdays, most village people use public transport motorcycles that seat four people --
one in front of the driver and three behind. The fare is P1000 (about US $0.40) each pas-
senger for the 30-minute ride through a rocky and gravelly road. Trips to and from the
village frequently require a long wait because the motorcycle driver would not go unless
there are three passengers. Passengers frequently get their feet wet during the river
crossings. During Sunday, which is usually market day, two “Asian Utility Vehicles”, that
ordinarily accommodate 17 passengers, ferry people from the village to the town center.
The fare is half of the motorcycle fare -- P5.00. Because there are only two trips in the
morning and two in the afternoon, these vehicles are always packed with passengers. I

counted 46 passengers during one trip.

Since the village was my “laboratory”, I decided to live in the village during the

field research. The head of the house where I stayed is a rice farmer while his wife works

5351

 

Bathe

l
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42

as a stool collector of the World Bank-funded schistosomiasis component of the Philippine
Health Development Project (See Acknowledgements: Arturo and Juanita Adlawan).

Both of my hosts were born in the village and have lived in it for much of their lives. Both
of them gave me valuable insights into village life, customs and traditions. The wife serves
as the Secretary of the village governing body. Their house stands opposite the Macanip

Elementary School, where the RITM holds its annual screenings and treatment.

Recruitment of Field Guide and Interpreter

Throughout the length of my stay in the village I was aided constantly by my guide
and interpreter (See Acknowledgements). He is a village councilman and the treasurer of
the “Samahang Nayon,” the association of farmers in the village. I needed an interpreter
because I could not speak and I barely understand the local dialect. Although the villagers
understand Tagalog, the Philippine national language, most prefer to talk in the local lan-
guage called waray. A high school graduate with two years of college education, my
guide acts as field supervisor of RITM’s water contact study in the village. Because of
this position, he is familiar with most of the aspects of schistosomiasis in the village. I
found these qualities to be very useful when we had to translate the questions in my inter-
view schedule from English to waray. His understanding of the transmission process pro-
vided me with valuable insights into the schistosomiasis disease system in the village dur-
ing our discussions and interviews. An added advantage for my purposes is the fact that
he together with two assistants had just conducted a population census of the village six
months before my visit. His knowledge of the village population and their house locations
was therefore current at the time of my survey. His familiarity with the layout of the vil-
lage including the location of houses was particularly valuable when I mapped the village

using the compass traverse method.

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43

Method of Data Gathering

Socioeconomic survey

An interview schedule, which is shown in the Appendix, was the main socioeco—
nomic survey instrument that was used in this study. I formulated the questions in the in-
terview schedule with the objective of eliciting information on the human component of
the schistosomiasis disease system. Its preparation involved three phases. In the first
phase, I drafted a set of open-ended questions based on my study objectives and my re-
view of the literature. With these questions in mind, I devoted my first few days going
around the village observing patterns of life in the village. I took note of the patterns that
I deemed to be key elements of the schistosomiasis transmission cycle. At the same time,
I discussed my initial set of questions with my hosts, my interpreter, a coconut farmer, a
rice farmer, a schoolboy, the President of the Irrigators Service Association of the village,

and the municipal agricultural technician assigned to the village (See Acknowledgements).

During the second phase, I re-cast the questions into a form that is compatible with
the village setting. I drafted the questions in English and subsequently translated them into
waray with the help of my interpreter. I knew a little of waray because my father, being
from the adjacent province of Samar, spoke it fluently. I picked up the dialect from him
and from my relatives. I grouped the questions under the headings of demography, water
contact behavior, living conditions, household expenses and income, livelihood, ownership
of animals, health seeking behavior, knowledge of the schistosomiasis transmission cycle,
community rating, attitudes and outlook, community participation, and attitudes and per-
ceptions toward schistosomiasis. Opposite the questions, I added the possible range of
responses, which I gathered during the initial open-ended interviews, and assigned numeri-
cal codes to each. This facilitated the recording of responses during actual interviews. It

also simplified the inputting of the responses into the computer.

44

During the third phase, I tested the interview schedule on 20 respondents. I made '
a purposive proportional sampling of respondents based on age, occupation, and location
of residence. Here I had the opportunity to make sure that the questions were clear
enough to be understood by the respondents and that very little was lost in the translation
process. I also wanted to know how long each interview would last. Because of the na-
ture of the questions, I deemed it necessary that the household head. be the respondent
To enable the respondents to thoroughly understand the questions and thus respond ac-
cordingly, the interview was conducted in waray. I decided that the questions will be
asked by my interpreter and I will record the responses. On the average, the interview

lasted one hour.

With few exceptions, we conducted the interviews in the respondent’s residence.
We usually made arrangements for the interview a day or two before. The spouse was
usually present during the interview. In cases where the husband was the respondent, I
found the presence of the wife to work to my advantage. My interpreter thought that the
husband usually was more truthful when the wife was present especially with regard to

income.

I conducted the household survey between March 8 and May 31, 1993 to deter-
mine the village's socioeconomic characteristics and the knowledge, attitudes, and prac-
tices of the people that may have a bearing on schistosomiasis prevalence. I was able to
include 251 households. This figure constitutes 77 percent of the total number of house-
holds in the village. The survey area is divided into 13 zones (see map on p. 55). All the
respondents are heads of households, 88 percent are married, and 90 percent are male.
Most of the respondents have very little formal education. More than 90 percent said that
they did not go to school or they had reached only the fourth grade of elementary educa-
tion. Thus, the majority of the respondents possess only the barest essentials of reading

and writing. Sixty-seven percent of the respondents were born in Macanip; 85 percent

hats
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45

have not moved from their residence within the past 5 years. The largest number of re-
spondents, representing 51 respondents or 20 percent of the total, come from Sitio Gapas
(Zone 10). Almost 40 percent come from the main settlement cluster, the village pobla—
cion, which is composed of Zones 1 to 5. Some household heads could not be inter-
viewed because they were deaf,‘mentally impaired, or too ill. Other potential respondents

deliberately avoided being interviewed.

Field mapping and aerial photo interpretation

The analysis of transmission patterns requires a clear locational component to be of
value for control programs. It is important to know where the people are being exposed
and where elements of the natural environment are most susceptible to intervention or
avoidance. In the case of Macanip, detailed field mapping was necessary because available
maps covering the village were either too small in scale or out of date that they cannot be
used for village level analysis of transmission patterns. For purposes of this village—level
study, I made a land use and settlement pattern map of the village. The base map that I
used was a 1:4,000 scale tax map in the Municipal Assessor’s office. The map, which was
plotted from information originally gathered in 1928, showed roads, waterways, individual
lot boundaries, and lot numbers within the village. Some of the latter had been updated.
Tax declarations from the same office listed the land use for each lot. I used this listing as
a starting point to plot land use on the base map. Taking due account of seasonal differ-
ences in agricultural land use, I field-checked the land use map and found it generally ac-
curate for analysis on the village scale. I supplemented this ground verification by examin-
ing black and white aerial photographs of the village that were taken in 1976. Using an
ordinary US Army prismatic compass that enabled azimuth compass readings, I plotted
the location of all houses in the village by compass traverse method. Since there are no
natural or man-made delineations on the ground, the boundaries of the political subdivi-

sions of the village that I plotted on the map are only approximate.

 

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46

From the National Cartographic Authority of the Philippines with offices in Fort
Bonifacio in Makati, Metro Manila, I was able to obtain a 1:50,000 topographic map that
contained Macanip. The map was made based on aerial photography done by the US
Army between 1947 and 1953. It showed that Macanip was a rice-production area in that
period. I used it to examine the topography and land use in and around the village. From
this map, I calculated the average slope and elevation in the village. This map was too

small in scale for analysis at the sub-village level.

The RITM commissioned a licensed surveyor to make a map of a portion of the
village that was used for its water contact studies. I was given one copy that showed the
locations of the 31 water contact sites, houses, and waterways. Together with an RITM
field observer, 1 inspected each of the water contact sites and took color slide photo-
graphs. To indicate the location of the water contact sites, the RITM placed numbered
metal plate markers nailed to coconut trees, or attached to wooden posts. I ground-

checked the accuracy of the map and found it to be reliable.
Village Census

RITM undertook a census of inhabitants in June 1992. The census revealed that
there were 1,701 inhabitants in the village. This population was distributed in 327 house-
holds resulting in an average household size of 5 inhabitants per household. There are
more males (52 percent) than females (48 percent). Fifty-three percent of the population
are between the working ages of 15 and 65. The dependent age group 0-15 constitute 42
percent. Thirty-seven percent of the households are located in the main settlement cluster

in the center of the village.

Snail Infection Data

RITM provided snail infection data from two cycles of observations: the first cycle

was from August to October 1992 while the second was from March to June 1993. The

cntnh
of Si;
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47

combined collection for these two periods amounted to 17,803 snails. The total number
of snails collected during the first period was low: only 2,762 or 15 percent of the total.
Some sites contained no 0. quadrasi although they did contain other snails. Other sites
contained 0. quadrasi, but none were infected while still other sites contained 0. quadrasi
of which only a few were infected. In the second cycle, the RITM increased the chances
of finding snails by increasing the number of field workers collecting at each site and by
“baiting” the sites with dead banana leaves three days before the collection. Each site was
searched by four field workers for one hour during the day that the site is scheduled for
snail collection. The snails that were collected were placed in petri dishes containing wet
filter paper, and brought to the Schistosomiasis Research and Training Center laboratory

in Palo for identification and crushing.
Parasitological Data

The RITM provided me with parasitological data showing the intensity of infection
for individuals who participated in their annual schistosomiasis treatments during the years
1982-1992 (no data for 1988). The data were in Dbase 111 format and contained the fol-
lowing fields: name, subject ID, date of examination, egg count per gram of stool, age,
and sex. The number of individuals examined varied yearly from a low of 851 in 1984 to
a high of 1552 in 1989. The data showed the number of schistosome eggs per gram of
stool as determined by the modified Kato-Katz method. Almost half of the individuals
examined by RITM during the lO-year period did not live in the village. Relatives and
friends of the villagers apparently took advantage of the free annual schistosomiasis ex-
amination and treatment. For purposes of this study, I discarded the records of the non-
residents of Macanip. Likewise, I did not use the records of those individuals who were

not listed in the June 1992 census (Table 3.1).

48

Table 3.1. Macanip Schistosonriasis Infection Records

 

 

 

 

 

 

 

 

 

 

 

 

 

1982-1992
Year No. of Records Received Number of Records
from RITM Used in this Study
1982 1 158 493
1983 1010 472
1984 851 419
1985 1021 474
1986 1087 565
1987 1075 602
1988 none none
1989 1552 623
1990 1232 663
1991 1075 679
1992 964 547
Total 1 1025 5537

 

 

 

 

 

Parasitological data were obtained from Macanip residents through informational
meetings and close cooperation with village leaders. On anival of RITM doctors in the
village, word was passed around through unit leaders that the RITM team had arrived and
that there would be a meeting in which examination and treatment procedures would be
explained. During the meeting, an RITM doctor explained to the villagers the importance
of their cooperation in the treatment and study of schistosomiasis in the village. Five stool
cups per individual were distributed to households that were in the water contact study
area. The need for diagnostic accuracy in the water contact study was the reason why five
stool samples were given per individual. For the rest of the village, only one stool cup per

individual was given. The stool cups were picked up by four village-based field workers

49

of the RITM the following morning. Only one stool cup was collected each morning per '
individual. Thus, five stool samples for five days were obtained in the water contact study
area; only one stool sample was obtained for the rest of the village population. Samples
from the collected stools were immediately mounted on glass slides (using the Kato-Katz
technique) by two trained workers. These slides were later transported to the Schistos-

omiasis Research and Training Center in Palo, Leyte for counting of schistosoma ova.
Water Contact Data

The RITM also provided field data in Dbase 111 format on water contact observa-
tions and snail infection data in 31 observation sites in a portion of the village. RITM
classified the 31 observation sites into eight water types. As shown in Table 3.2, 12 or 40

percent of the water types are paddy fields.

The targets of the water contact observations were 480 persons belonging to 86
households located in the sitios (hamlets) of Gapas, Guinwalohan, and Cutay-Sapa. Each
of these individuals was given an identification number. Painted metal plates nailed on the
front of the houses indicated household numbers. The water contact sites were likewise
marked through easily visible painted metal plates nailed on trees or placed on chest-high
wooden stakes. There were two cycles of observations: the first was conducted during
the last quarter of 1992 and the second was made during the second quarter of 1993.

Each cycle comprised ten periods of 8 days, as follows:

 

Day 1 water contact observations at site a

 

Day 2 snail collections at site a

 

Day 3 water contact observations at site b

 

Day 4 snail collections at site b

 

Day 5 water contact observations at site 0

 

Day 6 snail collections at site c

 

Day 7 rest

 

 

 

 

Day 8 rest

 

50

Table 3.2. Water Contact Observation Sites

 

 

 

 

 

 

 

 

 

 

 

Macanip, Jaro, Leyte, Philippines
Number of
. . Number of Site Num- Valid 0e % °f ”‘31 % °f ”‘31 % °f ”‘31
Descrrptron . . obs., 92 & obs., 1992 obs., 1993
Sites bers servations, 93 on] * on] n
92 & 93 V 5’

Mam river (Marnrt river 4 2, 12, 22, 862 37.1 25.5 513
only) 31
Small river (Taytay and
Mamlag rivers) 3 7, 17, 20 325 14.0 10.4 18.3

Large irrigation canals 3 3, 13, 23 323 13.9 17.4 9.5
Small irrigation canals 3 8, 18, 28 16 0.7 -- 1.5

1’ 4’ 6’ 9’
Paddy fields (rice plan- 11, 14, 16,
tation beds) 12 19’ 21’ 24’ 479 20.6 25.7 14.3
26, 29

Seepages (ground with
soft soil with still or
sluggish water and
vegetation; muddy 2 5, 27 218 9.4 13.4 4.4
ground with creek/river
runoffs)
Flood pool (ground de-
pressions that stay un-
derwater most of the 2 10, 25 31 1.3 1.9 0.6
time including small
swamps)
Carabao wallow (deep
ground depressions filled
with water that is most
often used by (arabaos; 2 15, 30 72 3.1 5.6 --
water is almost always
cloudy or muddy)
Total 2326 100 100 100

 

 

 

 

 

 

 

* covers the mouths of August, September, and October
** March, April, May, and June

Source: Author’s analysis of RITM data.

 

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51

Table 3.3. Number of Water Contact Observations Per Site, 1992 and 1993

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Site Type Date Observed Day of Week. No. of Observations % of Observations
1992 1993 1992 1993 1992 1993 Totl 1992 1993 Totl
1 Paddy 8/12 fig: 3 4, 2 73 81 154 5.7 7.8 6.6
3/20
2 M. River 8/14 4/29 5 6, 4, 86 100 186 6.7 9.6 8.0
6/11 5
3 L. Canal 8/16 3/22 7 1 49 4 53 3.8 0.4 2.3
4 Paddy 8/20 3/26 4 5 60 8 68 4.7 0.8 2.9
5 SeepagL 8/22 3/28 6 7 112 40 152 8.7 3.8 6.5
6 Paddy 8/24 3?;30 1 7, 2 43 18 61 3.3 1.7 2.6
7 5. River 8/28 213:, 5 6, 4 30 79 109 2.3 7.6 4.7
8 8. Canal -- 4/5 -- 1 -- 3 3 -- 0.3 0.1
9 Paddy 9/1 -- 2 -- 6 -- 6 0.5 -- 0.3
10 Fld Pool 9/5 -- 6 -- 13 -- 13 1.0 -- 0.6
1 1 Paddy -- -- -- -- -- -- -- -- -- --
. 4/15
12 M. River 9/9 5,25 3 4, 2 53 34 87 4.1 3.3 3.7
13 L. Canal 9/13 4/19 7 1 49 26 75 3.8 2.5 3.2
14 Paddy -- 4/21 -- 3 -- 3 3 -- 0.3 0.1
15 Wallow -- -- -- -- -- -- -- -- -- --
16 Padd -- 3’ 18 -- 4 2 -- 18 18 -- 17 0 8
V 4/27 ’ - .
3/20
17 8. River 9/23 4/29 3 6,4,5 22 54 76 1.7 5.2 3.3
6/11
18 3. Canal -- 3/22 -- 1 -- 13 13 -- 1.2 0.6
19 Paddy .- 3/26 -- 5 -- 6 6 -- 0.6 0.3
20 5. River WI 37278 4 5. 7 82 58 140 6.4 5.6 6.0
21 Paddy -- 3/30 -- 2 -- 11 11 -- 1.1 0.5
22 M. River 10/7 54,233 3 6. 4 188 298 486 14.6 28.6 20.9
23 L. Canal 10/9 4/5 1 1 126 69 195 19.8 6.6 8.4
24 Paddy -- 4/7 -- 3 -- 4 4 -- 0.4 0.2
25 Fid Pool 10/15 4/11 4 7 12 6 18 0.9 0.6 0.8
26 Paddy -- -- -- -- -- -- -- -- -- --
27 Sm 10/19 4/27 1 2 60 6 66 4.7 0.6 2.8
29 Paddy 10/25 —- 7 -- 148 -- 148 11.5 -- 6.4
30 Wallow 10/27 -- 2 -- 72 -- 72 5.6 -- 3.1
. 6/‘2 -- --
31 M. River -- 4,23 -- 3. 5 103 103 9.9 4.4

 

 

 

 

 

 

 

 

 

 

 

 

 

Source: Author’s analysis of RITM data

 

 

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52

The chosen format allowed observations on both weekdays and weekends. As
originally intended by RITM, the format would allow each of 30 sites to be observed once
and collected once in each 80-day cycle. As shown in Table 3.3, however, some sites did
not have any observation records while other sites were observed more than once during
the 80—day cycle. In the 1993 observation cycle. for instance, Sites 2, 12, and 31, which
are parts of the Mainit River, were observed more than once. The same is true for Sites 1.
6, and 16, which are paddy fields. Thus, one would expect a greater chance of obtaining
more water contact observations at these sites. Another confounding factor is the fact
that some sites like river crossings and seepages yielded point observations while other
sites such as paddies and the Mainit River yielded area observations that represented re—
cordings gathered over a wider area. Again, the chances of getting more water contact
observations in “area” sites are greater than those of “point” sites. These should be home

in mind when interpreting the water contact data.

The 1992 water contact data that was provided by RITM consisted of 1,600 ob-
servation records; that of 1993 consisted of 1360 records. The fields in the data set were
site number, date, day of week, observer, ID number, sex, age, time start of water contact,
time end of water contact, activity type, type of water, and degree of contact. Since the
data set was “raw,” records that could not be used had to be removed. The records that
were discarded include those of non-residents of the study area and cases wherein sex,
age, activity and type of water are undetermined. After data cleaning, the 1992 data con-
sisted of 1,284 water contact observations: 453 in August, 143 in September, and 688 in
October. The 1993 data, which contained the same data fields as the previous year’s data,
consisted of 1,042 observations: 222 in March, 544 in April, 208 in May, and 68 in June.
Many of the water contact sites had dried up by May 1993, which accounts for the lower

number of observations in May and June.

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CHAPTER 4

VILLAGE PROFILE

This chapter describes the physical and cultural circumstances in the village that

collectively exert an influence upon schistosomiasis transmission and control.

Physical Environment

Macanip is located in the municipality of Jaro in Leyte island, Philippines, which is
about 1,000 km from the southeast coast of the mainland of Asia. The village lies at
coordinates 11°09 ’north latitude and 124°47’east longitude. As shown in Figure 4.1, it is
situated on the western edge of a plain in the northeastern part of Leyte. The plain is 70
km long with a width varying between 10 and 20 km. The foothills of the Leyte Cordillera
mountain range are only 5 kilometers from the village’s southeastern boundary. The

nearest body of water is Carigara Bay, which lies 30 km north of the village.

The general configuration of Macanip is very similar to that of the lower peninsula
of Michigan, which looks like the back of a person’s left hand (Figure 4.2). The north-
western and southeastern boundaries are defined by creeks: Hambabalud (east) in the
southeast and Hambabalud (west) in the northwest. The village measures 5 km along its

north-south axis and about 3 km along its east-west axis. The municipal road, which is the

53

54

 

QWP‘PHS‘W Map of Leyte Province, Philippines

     
  
   
 
 

Schistosomiasis
endemlc areas

 

1:1: Macanip study area
Municipalities indicated

Leyte Gulf

Camotes Sea

Southern Leyte \
Province

Z—>

 

IE

Figure 4.1 Map of Leyte Province, Philippines. Source: Figure by
author; data from Blas, Bautista, and Lipayon, 1990.

 

55

 

 
   
   

 

 

Settlement Pattern
& Land Use*
Macanip, Jaro, Leyte,
— 11°10 '14 Philippines
500 m
I—L—I—I—I—J
— ll'oo‘N
1.30
4°
9 :9 curlau‘ylmnl M
96‘? Q 9 zone Numlu
4 mam”
Sidelines In inhaled
. , Road to:
--II 08 N A-Juo
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C-Pilogo
m P n -s.n Austin
1; 3 E -Malobago
.3 F .3 F-Villlpu
T 'Budonulthor'l field nrvey.Fekmry-Im 1993 T m

 

 

Figure 4.2 Settlement Pattern and Land Use. Macanip, Jaro, Leyte, Philippines.

 

mair
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56

main transportation artery of the village, runs in a southwest to northeast direction and is '
located in the upper half of the village. It connects Macanip with Canhandugan, the
village to its south, and northward to several other villages leading to the marketplace at
the town center of Jaro (A-B on map). The distance between Macanip and the town
center along this road is 10 kilometers. The road is composed of clay and gravel so that it
is vulnerable to torrential rains of the area. The location of this road renders the lower
half, especially the southeast, relatively inaccessible to motorized transport. Access to this
lower half is through a network of foot trails. There are also two smaller village roads
that can accommodate animal drawn carts. The first is the Pitogo-San Agustin Road (C-D
on map). which runs from north to south and connects Macanip with the villages of
Badiang and San Agustin in the south. The second connects Macanip with the village of
Villapaz in the east (F on map). These roads have a mostly clayey surface. Their width is
about 1.5 m.

Climate

The village is situated just off the eastern slopes of the central mountain range in

Leyte, which is exposed to trade winds blowing in from the Pacific Ocean. This windward
location is responsible for the copious amount of rainfall that the village receives
throughout the year. Runoff from the mountains also ensures sufficient amounts of water
for the stneams that run through the village. The nearest climatological station of the
Philippine Weather Bureau is in Tacloban City, which is 38 kilometers east of Macanip.
Since this distance is small, and the region is almost flat, it is fair to say that readings from
the Tacloban station can be applied to Macanip. The station recorded an average of 210
rainy days a year. The rainiest months are October to February. The average annual
rainfall is 2,216 millimeters. Prolonged dryness, which is not well tolerated by the snail
intermediate host of schistosomiasis japonicum, is unusual because rain is distributed

throughout the year. There are at least 15 rainy days per month. The range between the

Surfau

mm th:

futures

57

lowest and highest temperature is only 2 degrees Celsius. The mean annual temperature is '
27°C. The months of April and October are the warmest months with a mean of 28°C

while January and February are the coolest with a mean of 26°C (Table 4.1 and Figures

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4.3 and 4.4).
Table 4.1 Rainfall and Temperature by Month, 1951-1985
Station: Tacloban City
Month Rainfall Rainy Days Mean Temp

(mu!) (‘0

Jan. 262 20 26

Feb. 205 18 26

Mar 138 16 27

Apr. 121 15 28

May 146 15 28

Jun. 155 16 28

Jul. 167 17 28

Aug. 129 15 28

Sept. 147 16 28

Oct. 184 19 28

Nov. 245 20 27

Dec. 317 23 27

Total New 2216 210 27

Source: National Statistics Office. 1990. Leyte Provincial
Profile. Manila: National Statistics Office.
Surface waters

The main sources of surface water in Macanip are year-round rainfall and runoff
from the eastern slopes of the Leyte Cordillera. The natural and man-made surface water

features in the village assure plenty of opportunities for water contact and snail growth.

 

Source:

\_

«:52: :Q\E.:E

 

t K

SOUICE:
Ure '

. Fig

58

Figure 4.3 Mean Temperature by Month, 1951-1985
Tacloban City, Philippines

 

Mean Ternperatrure by Month, 1951-1985
Tacloban City, Philippines

28 ‘-

27 --

Temperature "C
3

25 ‘-

 

 

24 1 1. 1 1 a 1 . a a . A
l l l l l v v I v r I

Month

 

 

 

Source: National Statistics Office. 1990. Leyte Provincial Profile. Manila: National Statistics Office.
Figure by author.

Figure 4.4 Average Rainfall and Rainy Days by Month, 1951-1985
Tacloban City, Philippines

 

Average Rainfall and Rainy Days by Month, 1951-1985
Tacloban City, Philippines

Rainiaii (mm)
Rainy Days

 

 

 

 

Fl aintell + R ainy D ays

 

 

 

 

Source: National Statistics Office. 1990. Leyte Provincial Profile. Manila; National Statistics Office.
Figure by author.

ll\’ti3
Eastl
Paint
30001

180 n'

01 till
river 1
Mini
30hr
ended
Dime
than 8
Along

lbty n
genie
it If g

gil’in i

an

59

Fifteen rivers and creeks go through Macanip. These are the Mainit and T aytay
rivers and the following creeks: Mamlag, Morokborok, Hagosahis, Sapa, Hambabalod
East, Hambabalod West, Tuod, Badiang, Malobago, Carnpitlucan, Hambabaluray,
Palanog, and Binukot. The most important sources of water for rice cultivation are the
Mainit and Taytay rivers. According to village informants, water always flows in these

two rivers.

The most important surface water feature is the Mainit River. In terms of volume
of water flow, it is a secondary river among the rivers of the town of Jaro. The largest
river in the town is the Binahaan in the southeast and the Kabayongan in the west. The
Mainit river originates from the Alto Peak, a mountain that has an altitude of 1,100 meters
above mean sea level. It flows past the village of Canhandugan, another schistosomiasis-
endemic area, before reaching Macanip where it streams just west of the main settled area
of the village. Within the village, the Mainit River is shallow; in most places it is just less
than a foot deep. Thus, swimming is not possible and no bridges are necessary to cross it.
Along the edges of this river, the villagers have excavated shallow depressions in which
they wash clothes and bathe.

Settlement pattern

As shown in Figure 4.2, Macanip is composed of 9 sub-areas or sitios, which can
be regarded as large neighborhood groupings. For management purposes, the sitios were
given zone designations and each was placed under a unit or zone leader. The sitio names

and their corresponding zOne numbers are as follows:

and th:
Which .
contain

“flags.

31111631
[1115103
lies Ver
tilt mai
1991. (
River.

Catamt
tail of t
Campm

Eta. Ta

60

 

 

 

 

 

 

 

 

 

 

 

 

 

Sitio Name Zone Number
Poblacion 1- S
Talisay 6
San Antonio 7
Cagambahan 8
Morokborok 9
Gapas 10
Hambabalud 1 1
Cutay-Sapa 12
Guinwalohan 13

 

The main settlement cluster is located at the intersection of the Pitogo-San Agustin
and the municipal road. Macanip's five poblacion zones (1 to 5) constitute this cluster,
which contains 121 houses occupying a 200 by SOC-meter rectangle of land. This cluster
contains the village primary school, basketball court, church, and health station. Most

village-wide gatherings are held in this area.

Another settlement cluster is in Sitio Gapas, which contains 41 houses crowded in
a linear fashion along a BOO-meter stretch of the main village road. Farther south along
this road are 27 houses of Sitio Guinwalohan that are arranged in a linear pattern. Gapas
lies very close to the eastern bank of the Mainit River so much so that part of its land and
the main village road were eroded away during a typhoon and consequent flooding in
1991. Guinwalohan is bisected by the Mamlag Creek, which is a tributary of the Taytay

River.

The 3 sitios in the north of Macanip are Cagambahan, Talisay, and San Antonio.
Cagambahan, so named because it is composed mostly of members of the Gamba clan, lies
east of the Mainit River. Fourteen of the 20 houses in this area lie among rice fields. The
Campitlucan Creek, which is fed by a spring, is an important surface water feature in this

area. Talisay has 14 houses that are located near the Hambabalud Creek The houses are

ngltm

61

nestled beneath coconut trees. San Antonio has 12 houses: 8 houses in its northern
portion are under coconut trees while the 4 houses to the south near the Pitogo-San

Agustin Road are among rice fields.

Morokborok and Hambabalud constitute the southeastern third of the village that
is mostly under coconut trees. Compared to the other areas of Macanip, the houses in
these two sitios are dispersed over a wider area. In Morokborok, only 5 of the 29 houses
are among ricefields. The three creeks that run through this sitio are Morokborok,
Palanog, and Binukot. All the 11 houses of sitio Hambabalud are under coconut trees.

The three creeks that run through this area are Hambabalud, Sapa, and Katamyokan

Slope and elevation of the land

The village of Macanip lies at an elevation of 108.9 meters above mean sea level.
The elevation of the land decreases from the southern to the northern part of the village.
Between Macanip and its southern neighbor, the village of Canhandugan, the average land
slope is 2.9 percent. The topography of the land in the village is flat to undulating. Within
the village itself, there are variations in slope. The areas with the higher slopes in the
south and southeastern part are used mainly for coconut growing. The level lands in the
village are almost entirely under rice cultivation. These lands are located along the main
river. As calculated from map measurements, the average slope of the land is 0.9 percent.
Because of the gentle slope, the flow of water is sluggish; in certain areas water remains

stagnant.

Soils

The soils of the village are a mixture of the San Manuel silt loam and the Palo clay
loam (Jaro Municipal Development Staff, 1983). According to Barrera, Aristorenas, and

Tingzon (1954), the San Manuel soils, which cover most of the moderately drained flat

 

lott‘lat
of silt
sutfuct

human:

0f the t
amuun
surface
structur
takes 0
consult

and SW:

proud-c
even dh
P6811111.
lintost 1
“'43th
591 and
“7184110

mitt 0

62

lowland of Leyte, evolved from alluvial deposits. It has a higher proportion of sand than
of silt and clay and is fairly rich in organic matter. The water table is 2-4 meters from the
surface. In many areas of Leyte, these soils are extensively cultivated for rice, coconuts,

bananas, sweet potatoes, peanuts, and vegetables.

The Palo soils, which developed from recent alluvial deposits, are found in much
of the eastern lowland plain of Leyte island where schistosomiasis is endemic. It has equal
amounts of sand, silt, and clay, and no stones or rocks of any kind are found either on the
surface or in the substratum. The surface soil, which is brown clay loam of a fine granular
structure, is rich in organic matter from dead grasses and rice straw. This soil seldom
cakes or hardens from drying. The water table is usually about 1 m from the surface. It is
considered the best soil for agriculture in the island. Lowland rice, coconut, corn, cassava

and sweet potatoes are the most common crops cultivated (Barrera, et al.,1954).

The physical environment of the large lowland plain in which the village lies
provides preconditions for the persistence of Schistosomiasis japonicum infections. The
even distribution of rainfall throughout the year guarantees the presence of numerous
perennial, slow-moving waters in which the amphibious 0. h. quadrasi can persist. The
almost flat topography guarantees that worm eggs, hatched miracidia and cercariae are not
washed away by increased water flow velocity. The absence of roads and dry trails in the
east and southeast of the village means that residents of the hamlets have to traverse trails,
irrigation canals, and streams to be able to reach the poblacion and from there the town
center of Jaro. This increases opportunities for contact with infected water. Rivers,
creeks, and springs are places for washing and bathing and are sources of domestic water

supply. Irrigation ditches and small water impoundments are potential snail habitats.

The even distribution of rainfall and the minimal gradient of the land allows the
formation of aquatic environments in which humans, animals, the snail host, and the

parasite continually converge to perpetuate the schistosomiasis disease system in the

63
village. These environmental characteristics have spawned a rice cultivation system that
provides an abundance of opportunities for farmers and their families to be exposed to

potentially infected waters.

Socio-economic Characteristics

Population

The census conducted in June 1992 by the Research Institute of Tropical Medicine
listed 1,578 inhabitants in Macanip. Males slightly outnumber the females, 51 percent to
49 percent. Macanip has a young population: 40 percent of the inhabitants are under 15
years old (Table 4.2). The village’s poblacion (Zones 1-5) contains almost 40 percent of
its total population. Outside of the poblacion, the most populous sitio is Gapas, which

contains 17 percent of the village population.

Table 4.2 Population by Sex and Age Group

 

 

 

 

 

 

 

 

 

 

 

$51) Female Male Total Percentage

14 85 98 183 11.6
5-9 126 122 248 15.7
10-14 96 112 208 13.2
15-19 56 79 135 8.6
20-29 100 105 205 13.0
3039 96 95 191 12.1
4049 77 74 151 9.6
50-59 53 73 126 8.0
$0: 78 53 131 8.3
Total 767 811 1578 100

 

 

 

 

 

 

 

Somce of Data: RITM Census, June 1992. Data
collation by author: RLC.

64

Like the rest of the municipality, the population of the village has remained con-
stant for some time. Very little in-migration is taking place. Many young adults who have
acquired higher levels of education are moving out because the village offers few work
opportunities apart from farming. Sixty-seven percent of the respondents in the author’s
survey were born in Macanip; 85 percent have not moved from their residence within the
past 5 years. The population level is maintained by a high birth rate as evidenced by the
high proportion of children in the village.

The houses in Macanip are generally grouped along lines that follow kinship and
land tenure relationships. Relatives often build their houses close to one another. Thus,
any given spot in the village can be identified with a family group. The village was named
after the surname of its first settlers who moved in during the latter part of the 19th cen-
tury. The largest family groups in the village have the following surnames: Macanip, Gar-
rido, Gamba, Artoza, and Cabaltera. There are 326 households with sizes ranging from 1
to 11 members; the mean household size is 4.8. The single-member households are fre-
quently composed of the elderly who opt to live by themselves. Although these elderly
people live alone, their houses are usually adjacent to the dwellings of their children or
close relatives. Some single-person households are also occupied by mentally impaired

adults. Like the elderly, they live near the houses of close kin.

Most of the houses in Macanip are made of light materials like bamboo and wood
for walls, floors, and posts and cogon grass and nipa palm leaves for the roof. These
houses are built by the family itself with the help of relatives. Families that did not own
their houses generally are rice or coconut tenants who live in houses that were provided

rent-free by the landlord.
Rice cultivation

Almost one-half of the village land is utilized for rice cultivation. Most of the rice
farmers use the high-yielding varieties (HYVs) of rice. This practice started in 1978 when

65

the national government offered incentives to farmers to adopt modern rice cultivation
technology under the “Masagana 99” program. The hybrid varieties require greater
amounts of inorganic fertilizer, pesticides, and other inputs that all add up to higher pro-
duction costs. Macanip farmers usually use the 110- to 120-day HYVs of rice such as IR-
42, IR-74, or IR—72 that were all developed at the International Rice Research Institute.
However, foundation or certified seeds of these HYVs are rarely used due to high costs;
instead, second or third generation seeds are planted. Despite numerous incentives of the
government for farmers to adopt new rice technologies, farmers in Macanip are still faced
with the problem of low productivity because of their inability to apply the required
amounts of inorganic fertilizer and pesticides due to lack of funds. According to the
Municipal Agricultural Officer, only 6 farmers in Macanip availed themselves of the offer
to “buy 2 take lfree bag of fertilizer” during the December-January 1993 planting season.

Because of water constraints, triple-cropping using the 90-day HYV varieties of
rice such as IR-64 and IR-66 is seldom practiced. Farmers who insist on using these
short-maturing varieties within the regular planting cycle will see their rice crop mature
sooner. The problem, however, is that pests like water bugs, rats, and sparrows will con-
verge on their rice fields. Other favorites are local varieties such as "Kaborok" and
"Aklan." Farmers say that although the local varieties give lower yields, production costs
are not as high. Moreover, they say that the local varieties are more resistant to rice pests

and diseases.

In irrigated areas of Sitios Gapas, Guinwalohan, Cutay, and Cagambahan, two
croppings per year are possible: the first crop is planted in J anuary or February while the
second crop is planted in July or August. The rest of the village’s rice areas are rainfed.
In these areas, where only one cropping per year is possible, rice is planted in the rainy
months of December and January. It is followed by com that is planted in April to J une,

or legumes that are planted from March to June.

66

Several stages are involved in the practice of rice agriculture. Initially, the rice
fields are plowed and dikes are constructed or repaired to ensure proper water retention.
Farmers who do not own carabaos hire these animals for plowing and harrowing purposes
at a cost of 70 pesos per day. Laborers who specialize in dike construction and mainte-
nance are also hired at a wage of 30 pesos per day. A portion of the ricefield is set aside
for seed beds, which are prepared by plowing and harrowing before flooding and tram-
pling. Next, the rice seeds are sowed by broadcasting and raked into the soil. After 18 to
20 days, the rice seedlings are ready for transplanting. All members of the family except
for the very young and the very old are ordinarily enlisted to help in the transplanting of
rice seedlings. Farmers who have many fields hire laborers at the rate of 30 pesos a day,
plus meals. Three weeks after transplanting, the farmer enters the field again for fertilizer
top-dressing and weeding. During the first two months, the rice field is flooded with wa-
ter. During the third month, when the rice plants are 50 percent ripe, water is withdrawn
from the rice field. Pesticides, weedicides and rodenticides are applied to protect the rice

crop when available.
Irrigation

A large part of the rice-growing area of the village is served by with irrigation ca-
nals that enable two rice croppings per year. The National Irrigation Administration, a na-
tional government agency, has built a canal that streams through Guinwalohan west of the
main village road. From Guinwalohan, the canal runs under the village road and waters
the rice fields of Gapas east of the Mainit River. This canal is grass-covered and not well-
maintained. Water runs through it only after periods of heavy rain. The velocity of water
that flows through this canal is retarded by grass growth. In contrast, the farmer-main-
tained paods or small water impoundments and communal irrigation canals are well-main-
tained. These earthen paods and inigation canals were all built by farmers whose fields

will benefit from the additional water. The main irrigation canal gets its water from a

 

paodt
dun.’
hhuok
deS‘

Gmnw

lighti

tdnucn
mghtu
huspna
ucecrc
fifigaut
are 11561
dunun
VVhatd
finncrs
mrmg
”figaut
Pfimtss
mill 0V
[lint in

it'7g,

67

paod that is located at a point along the Mainit river between Sitio Gapas and the Pobla-
cion. This paod supplies water to the ricefields immediately east of the poblacion, parts of
Morokborok and Cagambahan. Another paod is located in the south of the village. It
draws its water from the Taytay River. This paod supplies water to the ricefields of

Guinwalohan, Morokborok, and Cutay.
Night irrigation and night fishing

The inadequacy of inigation water increases the schistosomiasis risk among rice
farmers in Macanip. About 31 percent of the respondents of the author’s survey go out at
night to divert irrigation water for their rice fields. The respondents further indicated that
this practice is done 3 to 6 times per week during the planting and growing stages of the
rice crop. This practice is especially true among farmers in Zones 9 and 11. There are
irrigation canals in these Zones but the water coming from the Mainit and Taytay Rivers
are used up in fields that lie near these rivers. The farmers whose fields are in the more
distant areas relative to the rivers must wait for dusk for their turn to irrigate their fields.
What these farmers do is to close the lateral gates of the inigation canal leading to other
farmers’ fields in order to channel the water into their own rice fields. They have to moni-
tor this process because farmers who are similarly situated will want to channel the limited
irrigation water into their own fields. The absence of a farmer watching this irrigation
process is usually construed as a tacit approval for other farmers to channel the water for
their own use. The time that this process is done, which starts from dusk, is a dangerous
time in so far as potential schistosomiasis infection is concerned. More than 80 percent of
the 78 respondents who said that they engage in night irrigation said that they do so be-
tween 6:00 p.m. and 8:00 pm. Studies conducted by Pesigan, et. al. (1958a) have shown
that the greatest risk of infection starts at dusk when about 80 percent of cercariae would

have swarmed or emerged from the host snail. Farmers who open or close the irrigation

68

gates at this time are very vulnerable because this activity involves water contact of the

feet and hands (See Tables 4.3 and 4.4).

Table 4.3 Number of Respondents Who Engage in
Night Irrigation and Night Fishing

 

 

 

 

Night % Night Fishing %
Irrigation
Yes 78 31 98 39
No 173 69 153 61
Total 251 100 251 100

 

 

 

 

 

 

 

Source: Author’s survey.

Table 4.4 Frequency of Night Irrigation and Night Fishing

 

 

 

 

 

 

 

 

Frequency Night Irrigation % Nrght Fishing %
Daily 1 l 14 0 0
Twice/week 18 23 4 4
3-6 times/week 38 48 8 8
Oncelweek 10 13 12 13
Once/month 0 0 43 45
Twice/month 2 3 28 29
Total 79 100 95 100

 

 

 

 

 

 

 

Source: Author’s survey.

To obtain additional food, almost 40 percent of the respondents engage in night
fishing. They usually start night fishing activities between 6 and 7 pm. Their method
involves using kerosene lamps to attract small crabs and fish as they wade through irriga-
tion canals, rivers, and creeks. Two-thirds of those who engage in night fishing do so

once or twice a month. (See Tables 4.3 and 4.4).

 

Cocont

product
which t
Mainit
book. i
streams
trees ha
effort u
titared
eight y:
Thus. c

dying.

Wort; is

COpra-r

69

Coconut cultivation

The other half of Macanip's land is planted to coconuts that are intended for copra
production. Copra is the the dried white nutrneat interior kernel of the coconut shell from
which coconut oil is extracted. The coconut lands are situated along the banks of the
Mainit River and in the southeastem portion of the village in Sitios Cutay-Sapa, Morok-
borok, and Hambabalod. A sizable number of trees also grow along the banks of the other
streams and along the edges of and interspersed among rice fields. Most of the coconut
trees have a definite owner and are given distinctive markings of ownership. Very little
effort is made towards the care and cultivation of coconut trees. The underbrush is
cleared only sporadically, and fertilizer application is not practiced. It requires seven to
eight years for a coconut tree to mature and, then it is productive for 50 years or so.
Thus, coconut farmers time their plantings of new trees to replace the old ones that are
dying.

The common practice in Macanip is to harvest the nuts quarterly. This harvesting
work is done by laborers who are paid 6 pesos per 100 nuts. The nuts are gathered in a
copra-making place where they are husked to remove the outer cover and then split into
two to remove the water inside the nut. They are then smoked and dried for 24 hours
over a grill-like structure that uses slow-buming coconut husks. After this drying process,
the nut meat is extracted and put into sacks. The sacks are then sold for cash to one of
the copra buyers in the village. The shells are collected and sold as cooking fuel. All
households in the village use coconut shells for cooking. Old coconut trees that are past

the fruit-bearing period are cut and used as coconut lumber.

Family income and expenditure
Income and expenditure patterns in the village show that most families in the vil-
lage do not earn enough to cover household expenses. To compensate for the deficit,

families often borrow money from relatives or moneylenders, promising payment in the

70

form of personal services or rice to be gathered at the next harvest. This practice results
in families being in a constant state of indebtedness. Their efforts to engage in more eco—
nomic activities to pay off debts often increases their exposure to potentially infected wa-

ters.

The main occupation of the working population of the village is farming. Because
there is a lag time between the quarterly harvests of coconut and the planting and harvest-
ing of rice, most workers have multiple occupations. The results of the author’s survey
revealed that only 38 percent of the respondents are owners of the land that they till.
Twenty-seven percent are tenants, while 22 percent are laborers. Twenty-nine percent of
the laborers among the respondents mentioned plowing and harrowing as their main activ-
ity. Thirty-eight percent said that they are mainly engaged in construction and mainte-

nance of dikes.

The productivity of the ricefields in Macanip is low. The reason for this, according
to the Municipal Agricultural Officer, is the failure of the farmers to follow the production
technician’s recommendations to increase agricultural productivity. The recommendations
often require higher production costs, which the farmers cannot afford. Moreover, the
farmers cannot innovate because they do not own the land that they till. Rice yields vary
between 40 to 60 cavans (one cavan = 110 pounds) of unhulled rice per hectare. The
value of the harvest is usually just enough to pay off the debts that the farmer has accumu-
lated. Farmers often have to borrow money because very little money or nothing is left for
the next planting season. Seventy-three percent of the farmers borrow from local lenders
to finance their farming activities. Only 11 percent are self-financed. Fourteen percent,

who are mostly tenants, borrow from the owners of the land.

The inhabitants of Macanip are generally poor. The mean family income in the
village is P16,746, which is less than half of the national average. The cluster of house-

holds in the northwestern portion (Zones 6, 7, and 8) of the village had the lowest mean

 

VF

N

\

r

alien

71

family incomes (See Table 4.5). Seventy percent of the households had a negative net
household income, which means that household expenditures exceeded household income.
Only 4 zones showed surpluses in mean family income. The respondents compensate for
the deficit by borrowing money from relatives or rendering personal services in return for

money or food.

Table 4.5 Family Income and Expenditure by Zone, 1993

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Zone Mean Annual Number of Mean Annual Number of Mean Savings/
Family Income in Families Family Expen- Families (Deficit)
Pesos (US $ 1.00 = Reporting diture in Pesos Reporting
25 pesos in 1993)
1 9,326 23 18,351 23 (9,025)
2 13,112 13 15,833 14 (2,721)
3 31,646 26 26,164 26 5,482
4 22,825 23 16,355 24 6,470
5 35,599 9 28,263 9 7,336
6 10,486 12 18,864 12 (8,378)
7 8,646 9 16,962 9 (8,316)
8 11,673 17 19,054 17 (7,381)
9 16,267 18 18,023 18 (1,756)
10 12,993 51 16.364 51 (3,371)
11 14,944 9 16,992 9 (2,048)
12 13,856 19 15,791 19 (1,935)
13 18,136 19 15,706 20 2,430
Village 16,746 248 18,326 251 (1,580)
Phil. 39,728 10,666 32,214 10,666 7,514

 

 

 

 

Source: Author’s survey. The Philippines’ mean family income was taken from the National Statistics
Office. 1988 Family Income and Expenditures Survey.

72

Most of the family income is consumed by food expenses. Seventy-nine percent of
the households have a daily per capita expenditure on food of 10.00 pesos or less. Thirty-
five percent of the households spent more than 80 percent of total household expenses on

food alone; 47 percent spent between 60 to 80 percent.

Animal husbandry

The most numerous animals are chickens, followed by pigs and dogs in that order.
At the time of the survey, there was an average of 1 dog, 3 pigs, and 7 chickens per
household. Chickens are usually fed with table scrap, unhulled rice grains, and coconut

meat. Table 4.6 shows the number and distribution of animals in Macanip.

The cows in Macanip are raised primarily for the meat market. During the survey,
1 did not see any cow that is used for farming or dairy purposes. The cows graze mostly
in the periphery of the village. Cows are present in only two zones, namely Zone 4 with 8

cows and Zone 13 with 9 cows.

In Macanip. goats are raised only for meat purposes. There were 21 goats in the
survey households. Most of the goats are raised in the coconut areas of Macanip. The
reason is partly due to the fact that goats may cause extensive damage to the rice cr0p if
they are allowed to graze near ricefields. The highest numbers of goats were found in

Zone 10. Zone 12 had the highest number of goats per household of 0.37.

Carabaos are used for plowing the land in rice fields preparatory to planting activi-
ties. They are also used to haul harvested nuts to the copra-drying areas of the village and
harvested rice grains to the rice mills. Carabaos are taken to carabao wallows and grazing
areas twice a day. Farmers habitually wash the mud off of them in streams or irrigation
canals after work in the rice field. A total of 132 carabaos was counted in the survey
households. Zone 10 claimed the highest number of carabaos but it was Zone 6 that had

the highest number of carabaos per household of 0.92. Zone 6 is in the northwestern part

73

of the village. Dogs and cats live in close contact with the village population. Because
dogs are allowed to roam freely, dog feces are a common sight around the residential ar-
eas of Macanip. A total of 265 dogs was counted in the survey households. The highest
number of dogs was found in Zone 10, but it was Zone 7 that had the highest average
number of dogs per household (2.78). There were 192 cats, or 16% of the population of
the surveyed households. Zone 10 had the highest number of cats. The zone that had the

highest average number of cats was Zone 7 with 1.44 cats per household.

Close to half of the surveyed households had 1 or 2 pigs that are tied or allowed to
roam freely at the backyard of the house. Their feces are washed down into inigation ca-
nals and streams when it rains. Only 13 percent of the households had more than 6 pigs.
Pigs furnish most of the meat for the village. Because of the its high price, however, pork
is seldom part of the ordinary family meal. It is reserved for weekends or special occa-
sions. The pig population suffers a precipitous decline in June at the time of the celebra-
tion of the barrio fiesta (feast in honor of the village patron saint). During this time, a

great number of pigs are slaughtered. Pork is the main fare in each household's banquet.

The total number of pigs in the surveyed households was 761, which is equivalent
to two-thirds of the total number of people in the surveyed households. Zone 10 had the
most number of pigs. This is mainly due to the higher number of households in this dis-
trict. The area that had the highest mean number of pigs was Zone 11 with 6.67 pigs per
household. People living in the coconut areas of the village generally have more animals
per household because of the availability of larger yards and more food in the form of co-

COIlllt meat.

 

 

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74

Table 4.6 Animal Population Raised in the Survey Households

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

March, 1993
No.of
Zone surveyed Cow Duck kaey Goat Carabao Dog Cat Pig Chicken
Households
1 23 0 0 0 0 10 17 19 48 178
2 14 0 0 0 l 3 10 18 32 81
3 26 0 20 0 0 16 26 17 83 144
4 24 8 2 6 0 13 18 11 60 73
5 9 0 0 0 0 5 10 8 36 47
6 12 0 3 0 0 11 13 11 37 138
7 9 0 2 2 0 8 25 13 26 115
8 17 0 0 0 0 10 17 12 48 156
9 18 0 0 7 0 6 17 9 52 180
10 51 0 11 O 10 20 49 31 131 203
11 9 0 0 0 2 1 9 9 60 134
12 19 0 2 0 7 16 23 16 70 257
13 20 9 6 8 1 13 31 18 78 185
Total 251 17 46 23 21 132 265 192 761 1891

 

 

 

 

 

 

 

 

 

 

 

Source: Author’s survey.

Rat population

In Macanip, rats live in the t0ps of coconut trees from March to June (dry season)
and during the planting season from October to December. The rest of the year they live
in rice fields. In each coconut tree, a male and female ratwould produce between 6 to 8
offspring (Arbas, B., 1994). Using a conservative figure of only 25 coconut trees per
hectare, I estimate that there will be 12,500 coconut trees in the 500 hectares of land in
the village that is devoted to coconut cultivation. Again using a conservative figure of 5
rats per tree, a rough estimate of 62,500 rats in the village is obtained. This translates to

an overall rat density of 62 per hectare, which is in accordance with rat population density

 

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75

estimates that were used in previous studies (Pesigan, et al., 1958a; Dumag, P.U., Gajudo,

C.E., Sena, C.Y., Cardenas, EC, and Fementira, EB, 1981).

Table 4.7 Uses of Different Sources of Water

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

March, 1993

Source D3213? % gfigg % Bathing % 82:21 %
Mainit River 1 0.4 124 49 106 42 15 23
T aytay River 1 0.4 23 9 25 10 16 24
Mamlag Creek 0 0.0 10 4 7 3 3 5
Morokborok Creek 0 0.0 7 3 2 5 8
iagosahis Creek 0 0.0 2 1 0 0 0 O
Sapa Creek 0 0.0 11 4 1 1 4 4 6
Hambabalod Creek 0 0.0 9 4 4 3 5
Tuod Creek 0 0.0 0 0 0 0 2 3
Badiang Creek 2 0.8 7 3 7 3 1 2
Irrigation Canal 1 0.4 O 0 3 1 13 20
Sprinj 112 44.6 16 6 22 9 1 2
Communal Water 0 0.0 2 1 2 1 O 0
System

Artesian Well/Hand 40 15.9 7 3 9 4 1 2
Pump

Open Dig Well 92 36.7 27 11 39 16

Rain Water Storage 0 0.0 0 0 0 0

Tanks

Others 2 0.8 6 2 5 2 2 3
Total 251 100% 251 100% 251 100% 66 100%

 

 

 

 

 

 

 

Source: Author’s survey.

Sources of water for domestic use

 

 

The main sources of drinking water are springs and open dug wells (Table 4.7).

These sources have been utilized for as long as the inhabitants of the village remember.

Only 16 percent of the households draw their drinking water from artesian wells or manual

 

76

hand pumps, which are generally privately owned. The govemment-built piped water sys-
tem is inoperative. The task of getting drinking water is usually delegated to children.
Drinking water is collected from springs and seepages twice a day, once in the morning
and another in the late afternoon, customarily by children who use one-gallon containers.

They often bathe or play at water collection sites.

The most frequently used surface waters are the Mainit and Taytay rivers. The
main reason for this is the proximity of these bodies of water to the poblacion and Gapas,
which are densely populated. Water is always present in the channels of these rivers. A1-
most half of the households use the Mainit River for washing clothes and bathing. Ten
percent use the Taytay river, while 11 to 16 percent use water from open dug wells.
Farmers who wash their farm animals use the Mainit river (23 percent), Taytay river (25

percent), and irrigation canals (20 percent).

Use of toilets

Sixty-nine percent of the households that were surveyed by the author do not have
toilets. One-third of those who have no toilets cited high cost as the reason for not having
a toilet. Most of the toilets in the village are pit latrines, water-sealed with an unlined
septic tank. In 1993, the construction of a toilet of this type requires six man-days of la-
bor, one bag of cement worth 100 pesos, plus 500 pesos for the roof and sides. The total
cost would amount to 780 pesos, which is equivalent to 26 days worth of an unskilled
farm laborer’s wages. Sixty-two percent said that building a toilet is too time-consuming

and that it is more convenient to defecate in the open (See Tables 4.8 and 4.9).

The low number of toilets in Macanip partly contributes to the persistence of schis-
tosomiasis in the village. The government had tried to encourage the use of toilets in 1986
by distributing 120 plastic toilet bowls. Funds for this activity came from the Schistos—

omiasis component of the World Bank-funded Philippine Health Development

77

Table 4.8 Number of Toilets, 1993

 

 

 

 

 

 

 

 

 

 

 

 

Type of Toilet Number %
None 173 69
Pit latrine, water-sealed, unlined septic tank 45 18
Pit latrine, water-sealed, septic tank lined with bamboo or wood 0 0
Pit latrine, water-sealed, septic tank lined with used steel drum 1 0
Pit latrine, water-sealed, septic tank lined with cement 32 13
Antipolo (not water-sealed) 0 0
Pit privy (not water-sealed) 0 0
Total 251 100

 

Source: Author’s survey. According to the 1989 IBON Facts and Figures, 70% of
Philippine households had sanitary toilets in 1988.

Table 4.9 Reasons for Not Having a Toilet

 

 

 

 

 

 

 

 

 

 

 

Reason Number %
Foul odor inside the toilet 0 0
Lot of work to dig pit/tank 24 14
Frequent transfer of residence 30 17
Destroyed during past typhoon 29 17
(November 1991)

More convenient to defecate in 25 14
the open/among bushes

High cost of materials 57 33
Not interested 7 4
Others 1 1
Total 173 100

 

 

 

 

Source: Author’s survey.

 

78

Project. The recipients were expected to construct the rest of the toilet. As an incentive
for the recipients to build toilets, the government gave five kilograms of rice. The incen-
tive was not enough, and many of the recipients did not have a strong motivation to build
a toilet. Many simply put the toilet bowl aside. Because of resource and personnel limita-
tions, the government failed to monitor the recipients’ compliance with the program. For
instance, seven years after the distribution of the toilet bowls, I met the sanitary inspector
of the town. He said he was in the village to check whether the expected numbers of toi-
lets were actually constructed. The World Bank was at that time conducting an evaluation

of the Philippine Health Development Project.

Table 4.10 Usual Defecation Area of
Respondents Who Do Not HaveToilets

 

 

 

 

 

 

 

Area Number %
Banks of Mainit River 4 2
Within bushes 120 72
Banks of streams 4 2
Within banana clusters 38 23
Irrigation canals 0 0
Total 166 100

 

 

 

 

 

Source: Author’s survey.

Based on the author’s survey, ninety-five percent of the respondents who have no
toilets defecate within bushes or banana clusters (See Table 4.10). Aside from providing
privacy to villagers while they are defecating, the bushes and other vegetation shade the
feces from the sun and retard the desiccation of the schistosomiasis ova. They do not ven-
ture too far from their houses when they defecate at dawn. The area of defecation usually
lies within a 25-meter radius from the respondent's residence. Defecating by adults di-

rectly on water is rare because of the absence or sparseness of plant cover on or at the

79

edge of irrigation canals, rivers, and creeks. Children, on the other hand, do not require
concealment. On many occasions, the author observed children depositing their stools di-
rectly into inigation canals. Thus, human schistosomiasis ova would likely be most abun-
dant near residential clusters. Because of the frequent rainfall in the village, the chances of
these ova being washed down toward the village’s numerous bodies of water are high. An
examination of the distribution of houses in the village could indicate several areas where
snail infection may be high due to miracidiae emerging from eggs in human stools. These
areas include the confluence of the Morokborok and Binukot Creek in Zone 9, the irriga-
tion canal and Mainit River near Zones 1, 3, and 5, Campitlucan Creek in Zone 8, Hamba-

balud Creek in Zone 6, Mainit River near Zone 10, and Mamlag Creek near Zone 13.

CHAPTER 5

WATER CONTACT AND RISK OF TRANSMISSION

The transmission of schistosomiasis depends on people having contact with in-
fected surface water. Water contact investigations aid in the understanding of prevalence
and intensity of infection in both sexes, different age groups and occupational categories.
The knowledge gained in these investigations may then be used in the selection of appro-
priate control measures and in the evaluation of the effectiveness of a control program.
Combined with studies of the snail intermediate host, water contact studies can indicate
when and where transmission occurs. This information is an important input to the formu-
lation of plans for snail control. In this chapter, the relative importance of various types of
human water contact activity and the types of places where such contacts occur in the S.
japonicum transmission cycle will be explored. The implications that these types of activ-

ity have on control activities will then be discussed.
Description of Water Contact Study Area

The water contact study area is located in the geographical center of Macanip
(Figure 5.1). Within this area, a wide range of types of water contact occur. The area
contains two of the largest perennial water bodies in the village namely, the Mainit and
Taytay rivers. Both of these rivers are used for bathing, washing clothes, collecting
drinking water, and playing. Farmers often wash the mud off of their bodies in these rivers
before returning home in the late afternoon after a day’s work in the rice fields. All the

rivers and streams in the study area are also sources of fish and small crabs, which are
80

81

 

Figure 5.1 Water Contact Observation Area

82

used to supplement the typical family diet of rice, dried fish, and vegetables. These fresh
fish and crabs are usually caught by farmers who go night-fishing. This activity starts at
about 6:00 pm and typically lasts for three hours. The night fisherman wades through the
shallow rivers and streams carrying a small kerosene lantern to attract the fish. Night
fishing activities in the village are mainly subsistence in nature. The catch is immediately
cooked and consumed by the family. Fish and crabs are also eaten as finger food during

tuba (coconut toddy) drinking sessions

The Mainit River is within 25 to 50 meters of the houses in the thickly populated
hamlet of Gapas. Its proximity to Gapas, clear waters, and shallow character, make it a
heavily used water body throughout the year. The distance between the opposite banks of
the river is about 40 meters. However, for most of the year the watercourse itself is nar-
row and twisting with depths varying between ankle-deep at its shallowest to just above
the knee at its deepest. Along its banks there are numerous shallow depressions wherein
the flow of water is slow. In these pockets of still or slow-flowing water, residents of Ga-
pas do their laundry, bathe, and play. Also along the river banks, several open dug wells

wherein water continuously issues from springs serve as sources of drinking water.

Except for some patches of coconut trees, the water contact observation area is
mostly devoted to rice cultivation. The fields in the eastern half of this area, especially
those near the rivers, are planted twice a year because of the availability of irrigation wa-
ter. The rest of the ricefields are rainfed and are therefore planted to rice only once a year.

After harvest in these rainfed areas, some farmers plant corn and vegetables.

The water contact observation area is covered by a network of large and small ini-
gation canals. The large irrigation canals get their supply of water directly from the Mainit
River. Large irrigation canals that have a firm bed, especially those in the northern portion

of the study area, are used as pathways by villagers in moving between the village pobla-

82

83

cion and Zones 11 and 12. The small irrigation canals are fed by water from the large ini-
gation canals and the small streams in the area. Farmers also use these small canals to

wash the mud off of their feet and their farm animals.

In addition to the open dug wells along the Mainit River, drinking water comes
from two seepages, and three pitcher pumps in Gapas, two of which are privately—owned.
Neighbors often are allowed to get drinking water from the privately-owned pumps, but
this access depends on good relations with the owners. The seepage at site 5 serves as
drinking water source of some of the residents of Cutay-Sapa while that in site 27 pro-

vides drinking water to households in the southern part of Guinwalohan.

Transmission Risk: Snail infection

The patterns of snail infection show that there were more snail-infected sites dur-
ing the drier period from March to June 1993. Seventy percent, or 24 out of 31 observa-
tion sites, harbored infected snails during the drier period. Although there were fewer in-
fected sites during the more rainy period between August to October 1992, snail infection
rates were higher. During this period, while only 9 out of 30 sites or 30 percent of the
sites contained infected snails, a higher rate of snail infection of between 5 and 7 percent
was obtained. This is consistent with findings of previous studies that discovered high
snail prevalence rates during the rainy season. The highest rate of infection was in site 3, a
large irrigation canal with 7 percent, followed by site 6, a paddy field with 6 percent, site
23 a large irrigation canal with 6 percent and site 29, a paddy field with 6 percent Be-
tween March and June 1993, the sites having the highest snail infection rate were site 21, a
paddy field with 7 percent, site 29, also a paddy field with 3 percent, site 13, a large canal
with 3 percent, site 1, a paddy field with 3 percent and site 3 a large irrigation canal with 3

percent (See Table 5.1 and Figure 5.2).

84
Table 5.1 Snail Infection Rate by Season and by Site

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Number of Snails % S “311“an (1 Number of Snails % SnailsIn f ected
Site Number and De- C°“°°‘°d August-October C°“°°‘°d March-May 1993
scription 11;;ng st-October 1992 (wet season) March-May 1993 (dry season)
(wet season) (dry season)

1 Paddy 0 - 600 2.5
2 Mainit River 0 - 168 0.6
3 Large Canal 192 6.8 1407 2.9
4 Paddy 79 0.0 334 1.2
5 Seepage_ 275 1.5 1579 0.1
6 Paddy 36 5.6 1117 0.3
7 Taytay River 0 - 0 0.0
8 Small Canal 119 0.0 827 0.0
9 Paddy 129 0.0 1868 0.1
10 Flood Pool 58 0.0 1123 0.4
11 Paddy 0 - 488 0.0
12 Mainit River 49 0.0 1435 0.8
13 Large Canal 24 0.0 240 2.5
14 Paddy 0 - 2031 0.7
15 Carabao Wallow 395 1.0 - -
16 Paddy 0 - 888 1.0
17 MamlaLCreek 84 0.0 1561 0.6
18 Small Canal 0 - 1325 2.3
19 Paddy 11 0.0 1290 0.9
20 Taytay River 0 - 700 0.0
21 Paddy 0 - 583 4.8
22 Mainit River 0 - 384 0.3
23 LarECanal 87 5.7 464 0.9
24 Paddy 130 0.8 464 0.1
25 Flood Pool 279 1.4 1417 0.4
26 Paddy 6 0.0 2640 0.8
27 Seepage 348 0.0 262 0.0
28 Small Canal 0 - 301 0.4
29 Paddy 120 5.8 1174 0.0
30 Carabao Wallow 341 4.7 777 3.0
31 Mainit River - - 811 0.4

Total 2762 10.5 15041 15 .9

 

Source of Data: Research Institutre of Tropical Medicine, Philippines. Data collation by author: RLC.

 

85

Village '5
Road

 

Figure 6.7 Prevalence of S. japonicum Infection of Snails by Season

 

 

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Based on the above observations of snail infection, it may be concluded that people
have a higher probability of being infected in the irrigation canals and rice fields of the vi]-
lage than in its rivers and creeks. Prolonged exposure to water in rice fields and frequent

washing of feet and hands in inigation canals make rice farmers a high risk group.
Gender and Age Difl’erences in Water Contact

Gender and age influences the frequency and duration of water contact In the
water contact study area, boys and men made more frequent contact with water than girls
and women, 58 percent to 42 percent (Table 5.2). This gender difference is more pro-
nounced during the planting season wherein males accounted for 62 percent of all water
contacts. More males were observed working or walking on rice paddies and grazing or
leading carabaos. Because there are more male rice farmers and laborers, this gender dif-
ference indicates that occupation may be a determinant of water contact activity. For both
sexes, the most frequent type of water contact is crossing, which accounts for 68 percent
of total observations. The dense network of streams and canals in the area plus the ab-
sence of footbridges at crossing points make contact with water a certainty. Crossing is
followed by bathing or washing parts of the body and drawing water from springs or open
dug wells. More females were drawing water and washing clothes than males, which indi-
cates that water contact activities that relate to household needs are mainly done by fe-
males in the village. Among the different age groups of both sexes, the most frequent
water contacts were observed in the 10 to 19 year olds. The males of this age group were
most frequently observed working in rice paddies and drawing water for household use.
The females were seen mostly drawing water, bathing, and washing clothes. Other age

groups that showed high frequencies were the 30-39- and the under 10—year olds. Boys

87

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88

below 10 years old had almost twice the number of water contacts compared to girls of

the same age category.
Frequency of Different Types of Water Contact Activities by Season

Seasonal differences exist in the frequency of the types of water contact activities.
Water contacts that are economic in nature dominate during the planting season. More
crossing, paddy work, and walking on water or wet paddy fallows occurs during the
planting season than the harvest season. Seventy-two of the 94 observations of paddy
work were recorded during the planting season (Table 5.3). During the planting season, a
larger portion of the licelands of the village are planted to rice because water is more
abundant. Thus, there is more work-related water contact for rice farmers and laborers.
In going to the rice fields where they will work for the rest of the day, farmers frequently
must cross streams, and irrigation canals. To reach a rice field located in site 11, for in-
stance, a farmer from Gapas will cross a wet paddy field (site 1), cross an irrigation canal,
ford the Taytay River, and cross a small irrigation canal (site 18). The higher frequency of
water contacts during the planting season is also due to the higher abundance of rainfall
that in turn increases the opportunities for contact with surface water. Higher tempera-
tures and lower rainfall amounts characterize the harvest season. Because the amount of
irrigation water decreases, the area planted to rice shrinks. The effect is a diminution in
the proportion of economic water contact and an increase in that of contacts that are do-
mestic in nature, such as bathing and washing clothes. As shown in the table, more in-
stances of bathing and washing clothes were recorded during the drier harvest season than

the planting season.

89

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90

Frequency of Water Contact by Type of Water Body

Distance to the main river seems to be a major determinant of water contact behav—
ior. Table 5.4 shows that the highest number of water contacts was observed in the Mainit
river, which accounted for 37 percent of the total. This is mainly due to its proximity to the
main cluster of houses in the water contact observation area. The importance of distance is
underscored by the fact that Site 22, which lies closest to the houses among the 4 observa-
tion sites, accounts for more than half of all observations along the Mainit River. The 10-19
year olds made the most frequent contact with the Mainit river. Rice paddies ranked second
among the most frequented water contact sites. Males outnumbered females in the rice

paddies by more than 2 to 1.

Contact with the different water types varied by season. More water contact in the
form of bathing and washing clothes takes place in the rivers and creeks during the drier
harvest season (Table 5.5). During the planting season, due to rice planting and associated
activities, more water contact occurred in paddy fields, large inigation canals, and seepages
and springs. There were no observations in the carabao wallows during the harvest season
due to two reasons: the first is that Site 15 was discarded as an observation site during the

harvest season; the second is that Site 30 had dried up.
Duration of Water Contact Activities

Most water contacts are only of short duration (Table 5.6). More than 80 percent
of all water contacts are less than 2 minutes in length. Although crossing accounted for 68
percent of the total frequency of contact, it made up only 12 percent of the aggregate expo-
sure period of all water contact observations. In contrast, while rice paddy work accounted
for only 4 percent of the total frequency of observations, it comprised 38 percent of the to-
tal water exposure time. People who were observed doing rice paddy work such as trans-
planting rice seedlings and those who were washing clothes had the longest average dura-

tion of exposure.

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ACtiv

Cross

(hazi
leadir
Draw
water
Gaflk
veget
Bafln
“ash

bodv

lfia§i
M
Padd
VVas
Clot}
Vvan
Watfi
w

 

 

TOta
\

SOUR

93

Table 5.6 Duration of water contact activities at 31 observation posts

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

. . Number of Number of Total expo- Average dura- Range of

Acuv1ty persons ob- Contacts sure period tion of exposure exposure
served min. min. min.

Crossing 376 1592 1614 1 1-1 1

Grazing,

leading 15 40 6O 2 1-15

carabaos

Drawmg 66 141 326 2 1-9

water,

drinking

Gathering

vcgctablcs 6 15 153 10 2-22

, fishing

Bathing 134 203 1874 9 1-174

washmg

body

“Wing: 18 20 254 13 1-72

sw1mm1ng

Paddy 26 94 4894 53 1-187

work

Washing 53 95 3351 35 1-203

clothes

Walking in

water, wet 48 1126 280 2 1'60

fallows

Total 742 2326 12896 6

 

 

Source of Data: Research Institute of Tropical Medicine, Philippines. Data collation by author: RLC.

 

94

Duration of Water Contact: Differences by Season, Type of Activities,
and Type of Water Body

The duration of water contact activities generally varied according to season. The
largest variation occurred in non-economic water contact activities such as bathing,
washing clothes, and playing in water (Table 5.7). Both the frequency and duration of wa-
ter contact involving these activities increased substantially during the drier harvest sea-
son. The total exposure period for bathing, for instance, increased from 280 minutes dur-
ing the planting season to 5,594 minutes during the harvest season. In contrast both the
frequency and duration of rice paddy activities decreased during the harvest season: from
72 observations during the planting season down to 22, and from 3968 minutes decreas-

ing to 1,016 minutes.

The duration of water contact at different water types reflect the nature of the
types of activities that dominate in them (Tables 5.8 and 5.9). The longest duration of wa-
ter contact, with a two-season average of 12 minutes, occurred in rice paddies where eco-
nomic activities are dominant. Since the Mainit and Taytay river are mainly used for do-
mestic activities such as bathing and washing clothes, water contacts were of shorter du-
ration with an average of 5 to 6 minutes. The average exposure time of 1 minute in large
irrigation canals, flood pools, and carabao wallows indicates that the most dominant form

of water contact in these water types is crossing.

A comparison of the duration of water contact by season and types of water shows
that average exposure at paddy fields is longer in the planting season than the harvest sea-
son (Table 5.9). The opposite is true in the case of exposure at rivers and creeks wherein
average harvest season exposure is longer than that in the planting season. More detailed
analysis revealed that the durations of water contacts were longer at sites located near
houses. During the planting season, above average water contact times were observed at
sites 4 (36.3 min.) and 6 (15.5 min.), which are both rice paddies adjacent to house clus-

ters along the village road in Gapas and Guinwalohan.

 

 

Ta]

F’—

; 1511111:

 

’I

‘ Crown
L—

Gtazm;
: 133111111;

mm:
l‘

 

i Drawn]
I Water.
I 111111111

1' Gathen'
: agent

1

{13111112
Bathing

'5 121-111m

My

Playing
SW
w

ipflddv

W1- -'
(A

Mann

1

l “1111':
l Wit;
1
' T013]
\

SQUIC

 

95

Table 5.7 Duration of water contact activities at 31 observation posts by season

 

Planting

S e a s o n
(24 August 1992 to 25 October 1992)

H a r v e s t
(22 March 1993 to 11 June 1993)

Season

 

 

 

 

 

 

 

 

 

 

 

 

Activity Number Total Average Range of Number Total Average Range of
of obser- exposure duration of obser- exposure duration
. . . exposure . . exposure
vations perrod ot expo- min vations period of expo- min
min. sure min. ' min. sure min. '

Crossing 917 933 1 1-11 675 681 1 1-4
Grazing,
leading 28 40 1 1-3 12 20 2 1-5
carabaos
memg 65 145 2 1-8 76 181 2 19
water,
drinking
Gathering
vegetables, 8 88 1 1 2-20 7 65 9 2-22
fishing
Bathing 64 280 4 145 139 5594 11 1-174
washing
body
Playing: 2 2 1 1 18 252 14 1-72
swrmnung
Paddy 72 3968 55 1-87 22 1016 46 3-159
work
washing 18 300 17 1-80 77 3051 40 1-203
clothes
Walking in
water, wet 110 236 2 1-60 16 44 3 1-6
fallows
Total 1284 5992 5 1042 6904 7

 

 

 

 

 

 

 

 

 

Source of Data: Research Institute of Tropical Medicine, Philippines. Data collation by author: RLC.

 

96

Table 5.8 Duration of water contact at 8 water types

 

 

 

 

 

 

 

 

 

 

 

Water Number of Number of Total expo- Average dura- Range of
type persons ob- Contacts sure period tion of exposure exposure
served min. min. min.

(“1:149:11“) 207 862 5088 6 1-203

river

(53:23” 99 325 1497 5 1-1 1 1

river

2:31;: 109 323 386 1 1-45

nals

23136113: 7 16 16 1 1-16

nals

Paddy 94 479 5578 12 1-187

field

23:12:: 87 218 228 1 1-1 1

Flood 12 31 31 1 1
0013

3:33:52 10 72 72 1 1

Total 625 2326 12896 6

 

 

 

 

 

 

Source of Data: Research Institute of Tropical Medicine, Philippines. Data collation by author: RLC.

 

97

Table 5.9 Duration of water contact at 8 water types by season

 

Water type

Planting

S e a s o n
(24 August 1992 to 25 October 1992)

H a r v e s t
(22 March 1993 to 11 June 1993)

Season

 

Number

Total

Average

Number

Total

Average

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

of obser- exposure duration :ngeutr): of obser- exposure duration Eggs“:
vations period of expo- :3: vations period of expo- :10;
min. sure min. ' min. sure min. '
Ma“? . 327 779 2 1-80 535 4309 8 1-203
(Marnrt)
river
Small
134 218 2 1-8 191 1279 7 1-111
(Taytay)
river
La?“ “’1' 224 286 1 145 99 100 1 1-2
gation ca-
nals
5m?“ ”‘1' - - - - 16 16 1 1
gation ca—
nals
Paddy field 330 4430 13 1-187 149 1148 8 1-159
SW3?“ 172 182 1 1-11 46 46 1 1
& springs
Flood 25 25 1 1 6 6 1 1
ls
Carabao
11 allows 72 72 1 1 - - - -
‘ Tom] 1284 5992 5 - 1042 6904 7

 

Source of Data: Research Institute of Tropical Medicine, Philippines. Data collation by author: RLC.

 

98

Frequency of Water Contact at Various Times of the Day

Some differences were observed regarding the time of the different types of water

contact (Table 5.10). Crossing was evenly distributed throughout the day. Close to 80

percent of all observations of paddy work were recorded before noon. Farmers start their

activities just after sunrise so that most of the work scheduled for the day are accom-

plished before the sun becomes too hot Bathing was most frequent before noon while

washing parts of the body was most frequent in the late afternoon among farmers return-

ing from work in the fields. The activities that showed a peak in the late afternoon, espe-

cially in the harvest season, were drawing water and playing or swimming in the water.

Table 5.10 Frequency of water contact activities at various times of the day

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

. . Before 9:00 Between 9:00 am Between noon After 3:00 Total

Actrvrty .
am and noon and 3.00 pm pm
Crossing 475 389 330 398 1592
Grazing, leading cara-
baos 23 3 8 6 40
.memg “‘6" mm" 37 19 23 62 141
1‘8

Gathering vegetables, 0 4 7 4 15
fishing
Bathing, washing body 53 64 29 57 203
Playing, swimming 5 4 2 9 20
Paddy work 41 31 9 13 94
Washing clothes 25 37 22 11 95
Walking in water, wet 37 41 42 6 126
fallows
Total 696 592 472 566 2326

 

Source of Data: Research Institute of Tropical Medicine, Philippines. Data collation by author: RLC.

 

CHAPTER 6

PREVALEN CE AND INTENSITY OF HUMAN INFECTION

This chapter describes the patterns of human infection in the village using 10 years
of parasitological data that were provided by RITM. It shows that although intensity of
infection and hence morbidity has been kept in check by annual chemotherapy, the preva-
lence of the disease has been more difficult to manage. This suggests that the rates of new
infections and reinfections are high and that many infected people are being missed by the
control strategy of selective chemotherapy. Further analysis reveals relatively high infec-
tion rates in the age and sex categories that were shown in the previous chapters to have

higher risks.
Prevalence of Schistosonriasis

At the start of RITM treatments in Macanip in 1982, prevalence was 45 percent
Prevalence rates sharply declined in the two years after the onset of annual screening and
treatment. These rates seemed to have stabilized by 1985, or 3 years after the start of
treatment Between 1986 and 1990, the prevalence rate gradually increased. Starting in
1990, prevalence sharply increased to the 1992 level of 48 percent, which is higher than it
was at the start of RITM treatments in 1982 (Figure 6.1 and Table 6.1).

Mean age prevalence rates during the period 1982-1992 indicate that prevalence
increases with age until it reaches a peak in the 10-14 year age group. Thereafter, preva-
lence declines with age except for a secondary peak in the 4049 age group. Except for
the 60+ age group, males have a higher level of prevalence than females. Among males
the highest prevalence rates occur in the 10-14 and the 15-19 age groups. (Figure 6.2 and

Table 6.2).
99

100
Figure 6.1 Prevalence Rate, 1982-1993

 

Percent

 

Prevalence Rate, 1982-1993
lVacanip. Leyte, Philippines

 

 

 

 

100

30 _ Partial results.
Spec Ial Study
Area Only.

60 ’ No data \ __ 10

4O - l

20 -

O L 1 4 1 1 1 1 1 1 1 1 1
1982 1984 1986 1988 1990 1992 1994

0 Prevalence Rate

 

Source of data Research Institute of Tropical Medicine, Philippines. Figure by author: RLC.

Figure 6.2 Age Prevalence, 1982-1992

 

Percent

 

80

Age Prevalence, 1982-1992
Macanip. Leyte, Phiipp'nes

 

60-

 

 

 

 

5-9 10-14 15-19 20-29 30-39 40-49 50-59 60 4»
Age Group
-. Males o Females 1. Teal

 

Source of data: Research Institute of Tropical Medicine, Philippines. Figure by author: RLC.

 

 

101

Age prevalence rates in 1992 show that the older age groups have higher prevalence lev-
els, the peak being in the 30-39 age group. The males follow this pattern. Among fe-
males, the pattern follows the 10-year average in which prevalence peaks in the 10-14 age

group. Among males, the pattern is similar (Figure 6.3 and Table 6.3).

There seems to be no discernible spatial pattern or clustering of prevalence rates
among the zones of Macanip. The 10-year average shows that Zone 13 in the southern
portion of Macanip has the highest prevalence. Ranking second is the group composed of
Zones 6, 7, 10, 4, and 9, which have prevalence rates ranging from 27 to 31 percent. In
1992, there were 7 zones out of 13 which had prevalences of 50 percent or above. These

are Zones l3, 7, 12, 4, 6, 10, and 9 (Table 6.4).

Intensity of Infection

The annual changes in the pattern of prevalence and infection are reflective of the
continuous battle between annual treatments and schistosomiasis reinfection in Macanip.
The egg load of infected persons in 1982 was 59 eggs/g stool, followed by a steep drop in
1983 and 1984. Infection rates rose again in 1985, only to be followed by a general
downward trend between 1986 to 1991. In 1992, mean egg loads of infected persons rose
again to 34 eggs/ g stool. Partial results from the 1993 screening and treatments that cover
the water contact study area show a sharp decrease to only 13 eggs/g stool (Figure 6.4).
These results cannot be extrapolated to the whole village because the study area has re-
ceived special attention from RITM in terms of information dissemination and induce-
ments to participate in the Water contact study. The low egg load may be reflective of the
high degree of participation of the inhabitants of the study area in RITM’s screening and

chemotherapy program.

The ten-year average shows that in general intensity rises in parallel with preva-

lence in the age groups between 1 and 14 years. The peak intensity among males occurred

102

in the 10-14 age group and in women in the 15-19 age group (Figure 6.5). In 1992, how-
ever, the patterns of prevalence and intensity of infection were dissimilar: while age
prevalence generally followed the 10-year average, intensity of infection differed because
the highest levels were found in the 1-4 age group (Figure 6.6). In 1992, infected indi-
viduals in Zone 11 had the highest mean intensity of infection, followed by Zones 13, 12,
and 10 (Table 6.5).

Annual chemotherapy has kept the intensity of infection to relatively low levels.
More than half of the population was uninfected in 1992, 41% were lightly infected (10-
100 eggs/g stool), 6% were moderately infected (101-400 eggs/g stool), and only 1.6%
suffer from heavy infection (>400 eggs/ g stool).

103
Figure 6.3 Age Prevalence, 1992

 

Age Prevalence, 1992
Macanip, Leyte, Phi'pp'nes

8O

 

 

 

 

 

O l l J l l 1 l l l
14 5-9 10-14 15-19 20-29 30-39 40-49 50-59 60 +
Age Group
l Able: o Ferralee * Total

 

 

Source of data: Research Institute of Tropical Medicine, Philippines. Figure by author: RLC.

Figure 6.4 Intensity of Infection, 1982-1993

 

 

Egg Load per Gram of Steel of Infected Persons, 1982-1993
Macanip, Leyte, Philipp'nes

 

 

 

 

 

70
6° - No ride
1.
E Pam reulte.
50 #- aaecld Study
0 . AmONy.
3 w -
v I-
g 30 I- ".
s -
I8 I- 3.
fl -
O 1 1 4 1 1 1 1 1 1 1 1 1
982 984 986 988 990 992 994
Yes

 

Source of data: Research Institute of Tropical Medicine, Philippines. Figure by author: RLC.

 

104
Figure 6.5 Intensity of Infection by Age Group

 

Mean Intensity of Infection by Age Group
Macanip. Leyte, Philippines. 1982-1992

1-4 5-9 10-14 15-19 20-29 3069 40-49
Age Group

 

Eggs/g Stool (Geometric than)

     

 

 

 

     

50-59 60 +

C3 Vales ea Females I Total

 

 

Source of data: Research Institute of Tropical Medicine, Philippines. Figure by author: RLC.

Figure 6.6 Intensity of Infection by Age Group, 1992

 

Intensity of Infection by Age Group, 1992
Macanip, Leyte, Philippines

140

 

120 -

80-

60-

   

40-

Eggs/g Stool (Geometric Mean)

20-

 

 

 

55:

~.-.- .' a '.
3:3:- :3".

>- :v-c . . .

1-4 5-9 10-14 15-19 20-29 30-39 40-49 50-59 60 +

Age Group

C3 Vales Fanales I Total

 

 

Source of data: Research Institute of Tropical Medicine, Philippines. Figure by author: RLC.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 6.1 Prevalence and Intensity of S. japonicum Infection by Gender
and by Year, 1982-1992,Macanip, Jaro, Leyte, Philippines

Males Females Total
Year No. % Mean No. % in- Mean No. % Mean
exam. infect. gig/E exam. feet Egg/5 exam. infect. :5:le
1983 m 29 4:335 225 25 3:228 472 27 3:32?
1984 221 14 2:137 198 12 41;)?" 419 13 331:?
1985 244 13 ”(:2)” 230 8 53:3)” 474 11 6:31;?
1986 301 16 696:8)” 264 7 796;)“ 565 12 72016)”
1987 322 31 6954)“ 280 16 922:8)” 602 24 78:63
1989 335 27 4%)" 288 19 4221736 623 23 452:;
1990 341 21 452309 322 17 411236 663 ‘9 432516
1991 356 35 4242;; 323 25 3:138 679 30 483:5
1992 290 54 “(36 257 41 “(is)” 547 48 79233;”
£33 2919 29 723?; 2618 21 6:336 5537 25 6:334

 

 

 

 

 

 

 

 

 

 

* Mean arithmetic egg counts/g stool of infected individuals 1 SE (geometric mean)
Source of data: Research Institute of Tropical Medicine, Philippines. Data collation and calculations by
author. RLC.

 

106

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 6.2 Prevalence and Intensity of S. japonicum Infection by Gender and
Age, ll-Year Means, 1982-1992 , Macanip, J aro, Leyte, Philippines
Age Males Females Total
. M . .

14 240 8 733:1)” 223 5 52653)” 463 7 6:335
5-9 551 29 61%;” 480 19 “(3&2)“ 1031 24 652;?
1014 405 37 10:3)“ 345 30 95025022 750 34 mag)”
15-19 194 37 98;)” 114 23 833:6? 308 32 936;)”
20-29 281 34 7950)“ 242 21 “2,313 523 28 6922234
3039 400 30 6158;] 419 19 ”(2:9)” 819 24 5g;
40.49 425 32 5:238 358 27 532:7 783 30 532:)6
50.59 296 26 492:; 275 19 5758)” 571 23 43:)"
60 + 127 18 432:: 162 21 322:6 289 20 3(92‘;
Total 2919 29 7:335 2618 21 6:32;)“ 5537 25 6:334

 

 

 

 

 

 

 

 

 

 

"' Mean arithmetic egg counts/g stool of infected individuals :1: SE (geometric mean)
Source of data: Research Institute of Tropical Medicine, Philippines. Data collation and calculations by
author: RLC.

 

107

Table 6.3 Prevalence and Intensity of S. japonicum Infection by Gender and Age,
1992, Macanip, Jaro, Leyte, Philippines

 

 

 

 

 

 

 

 

 

 

 

 

 

Age Males Females Total

33 3 33 11:3,“ 3 3 1:22:35 3 33 ”:87
5-9 53 52 1133336 49 37 6:33:30 101 44 920:7)”
33 33 33 3 33 33 786‘“
2029 27 59 ”1:517; 12 22 23 61:3?” 49 43 17:53)“
33 33 683° 33 33 ”(433‘ 33 33 68;"
3333 33 33 2:52: 3 33 33 3
5059 34 53 31223;)” 22 45 513332)” 56 50 42:17?
60 + 18 39 231335 19 47 2203)“ 37 43 2:136
Total 290 54 ”($6 257 41 7186)“) 547 48 79233;"

 

 

 

 

 

 

 

 

 

 

* Mean arithmetic egg counts/g stool of infected individuals :1: SE (geometric mean) 4

Source of data: Research Institute of Tropical Medicine, Philippines. Data collation and calculations by
author: RLC.

 

108

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 6.4 Prevalence and Intensity of S. japonicum Infection by Gender and by
Zone, ll-Year Means, 1982-1992, Macanip, Jaro, Leyte, Philippines
Males Females Total

Zone No. % Mean No. % Mean No. % Mean
exam. infect. xii/E exam. infect :fifi’fi exam. infect xii/g

1 375 30 7:31;)” 308 18 432:; 683 25 6:3?

2 209 21 6369)” 204 20 42533-38 413 21 51213;]

3 372 24 422:9 373 9 532;“; 745 16 4:32:38

4 293 29 813136 246 26 ”(:2)” 539 28 “(:4)“

5 129 26 4:23;)” 169 16 3:5: 298 20 432:?

6 132 41 ”(318)” 168 24 8’30? 300 31 826:9)”

7 135 32 55221;)” 96 25 “(2331 231 29 5:21;?

8 194 26 5:234 182 20 “(£4 376 23 5‘39)”

9 217 27 622:9? 185 28 62:8? 402 27 610:8?
10 385 35 “(23;)“ 320 23 42);)6 705 29 6323;?
11 64 20 10(13:)66 44 18 286(5i4)231 108 19 17241396
12 276 28 9:33;? 216 24 “(74:)” 492 26 ”(33:)”
13 138 41 8362)” 107 39 432359 245 40 67638
£11]; 2919 29 7:335 2618 21 622336 5537 25 6:334

 

 

 

 

 

 

 

 

 

 

* Mean arithmetic egg counts/g stool of infected individuals i SE (geometric mean). Source of data: Re-

search Institute of Tropical Medicine, Philippines. Data collation and calculations by author: RLC.

 

109

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 6.5 Prevalence and Intemity of S. japonicum Infection by Gender and by
Zone, 1992, Macanip, Jaro, Leyte, Philippines
Males Females Total

M No. . % 33:; No. . % $83,: No. . % 32:3;
exam. infect. stool ,, exam. infect. stool * exam. infect. stool a.

2 19 37 “(:2)“ 22 41 4654;” 41 39 4:33;
3 33 33 "a.” 33 33 92.3.7 33 33 61.3.38
4 26 69 1023:)“ 24 46 63224739 50 58 89( 31:029

3 3 33 231:: 33 33 48.36 33 33 38..”
7 15 73 “(31:2 9 44 4‘: 2i6 )18 24 62 8031245

3 33 33 “(38" 33 3 33 33
9 16 62 5935)“ 15 47 48;? 31 55 54025
.. 33 33 ”2’48“ 3 33 71.3.36 33 33 "a.“
11 10 10 (60) 5 40 1059:)45 15 20 92:1 )30
12 31 52 17252579 20 75 876$1 )22 51 61 13:51:)42
1;}; 290 54 85613016 257 41 71:50 547 48 796134;”

 

 

 

 

 

 

 

 

 

 

"‘ Mean arithmetic egg counts/g stool of infected individuals 1 SE (geometric mean). Source of data: Re-

search Institute of Tropical Medicine, Philippines. Data collation and calculations by author: RLC.

 

CHAPTER 7

DISEASE PERCEPTION AND CONTROL

One of the important components of a schistosomiasis control program is the edu-
cation of the public regarding the disease. The design of this education program should be
based on the knowledge, attitudes, and practices of the people in the target area. This will
make the control program relevant and acceptable to the people. This chapter, which is
based on the author’s survey, examines the villagers’ perceptions of schistosomiasis and its
impact, their knowledge of transmission and control processes, and their attitudes toward
the disease, control measures, and the control program. Later, it attempts to show the

relationship between these factors and the persistence of schistosomiasis in the village.

The hierarchical political structure of the village seemed to have been used effec-
tively to inform villagers about the arrival of the RITM medical team and to disseminate
information about schistosomiasis. Under this system, information is first presented to the
leaders of each of the 13 zones in the village who then fan out to disseminate the informa-
tion to residents in their respective zones. As shown in Table 7.1, seventy-two percent of
the respondents learned about schistosomiasis through this organized group process while
twenty-seven percent said that they learned about it through their own initiatives. At the
time of the author’s field survey, the local elementary school was not disseminating infor-
mation on schistosomiasis to schoolchildren. Since school-age children are the most vul-
nerable age group to schistosomiasis infection, efforts must be made to incorporate schis-

tosomiasis education in the school curriculum.

110

1 1 1
Table 7.1 Source of Information on Schistosomiasis

 

 

 

 

 

Number Percentage
Individual approaches 68 27%
Community organization or group process 179 72%
Mass media 2 1%
Total 249

 

 

 

 

 

Source: Author’s survey: N = 251

Through radio broadcasts, the respondents are well-informed about national and
regional affairs. Most of the households have a battery-operated transistor radio that are
tuned in to radio broadcasts emanating from radio station transmitters in nearby Tacloban
City. Table 7.2 shows that for news and information regarding village and local affairs,
the respondents rely principally on their friends and neighbors. For news regarding the
rest of the country, the respondents rely heavily on the radio. For village affairs, a secon-
dary source of information are elected village officials. For town and provincial affairs,
the secondary sources of information are town officials, employees of national agencies,

and the radio.

Since villagers rely heavily on neighbors and radio for news, schistosomiasis con-
trol programs should be designed so that information can be channeled through leaders of
neighborhood units and by way of radio advertisements. Reliance on neighbors for news
is the result of the fact that the neighborhood groupings in the village are based on kinship
lines. Thus, the neighborhood or unit leader is usually trusted and relied upon for infor-
mation. The RITM’s method of enlisting the support of unit leaders and its success in
getting the villagers to cooperate in its annual screenings and treatment provides further
evidence of the efficacy of using neighborhood groupings as the basis of information dis-
semination for control programs. The author’s survey revealed that radio soap operas are

favorite listening fare. Since the coverage area of the radio stations airing these soap

112

operas is mostly endemic for schistosomiasis, the Department of Health could persuade

writers to include schistosomiasis awareness in the script.

Table 7.2 Sources of Information Regarding Local and National Affairs

 

 

 

 

 

 

 

 

 

 

Village affairs Town & Province Rest of the country

Friend/Neighbor 74.5 67.5 9.6

Unit (hamlet) leader 7.6 2.4 -

Elected village officials 17.9 6.0 0.8

Town crier - 0.8 -

Town officials - - 10.8 1.6

Radio - 12.4 84.3
Television - - 2.8
Newspapers - - 0.8

Total 100% 100% 100%

 

 

 

 

 

 

Source: Author’s survey: N = 251

The majority of the respondents are aware that schistosomiasis is not directly
transmitted . However, the notion of the transmission cycle is unclear (Table 7.3). This
finding implies that the respondents do not see their own roles in the perpetuation of the
transmission cycle. Moreover, it suggests that the respondents will not understand and
hence, fail to cooperate with control programs that aim to break the weakest link in the
chain of transmission or stop the disease through multiple points of intervention in the
transmission cycle. Thus, control programs should make sure that the notion of the cycli-

cal nature of schistosomiasis is understood by the target population.

113
Table 7 .3 Can Schistosomiasis be Transferred Directly

 

 

 

 

 

from One Person to Another?
No 12.4%
Yes 4.0%
Don’t know 27.1%
Not sure 1.6%
Not directly 55.0%

 

 

 

 

Source: Author’s survey: N = 251

As shown in Table 7.4, almost two-thirds think that animals, especially dogs,
transmit schistosomiasis. These people think that schistosomiasis is acquired when people
step on the feces of infected dogs. The presence of blood in the dog’s stools are regarded
as an indicator of schistosomiasis infection. One-third of the respondents know that tiny
snails are somehow involved in the schistosomiasis transmission process. But even this
small number of people do not know the exact nature of the snail’s involvement in disease
transmission. The idea of the involvement of snails came mostly from observing snail col-
lectors of the RITM research team do their work. The manner by which the snail 0n-
comelania quadrasi transmits the disease is virtually unknown. A quarter of the respon-
dents are aware of the existence of the parasitic worm and its role in schistosomiasis in-
fection. The local term for the parasitic worm is "sistom," a minute worm that cannot be

seen by the naked eye that enters the body through wounds and roots of leg hair.

Table 7.4 Knowledge of the Elements of the Transmission Cycle

 

Free recall Prompted Don’tknow Not sure Total

 

 

 

 

 

 

 

 

 

 

Parasitic worm 25.5 31.5 37.1 6.0 100%
Tiny snails 29.9 20.3 45.0 4.8 100%
Animals 63.3 4.0 30.7 2.0 100%

 

Source: Author’s survey: N = 251

114

The respondents are aware that schistosomiasis is acquired in wet areas (Table
7.5). Streams and creeks are at the top of the ranking of responses regarding infection
sites. More than two-thirds of the respondents mentioned these places as areas where
schistosomiasis infection may be acquired. Coming in second with almost the same per-
centage of responses were the main (Mainit) river and rice paddies. This “awareness” is
partly the result of the on-going (at the time of the survey) water contact study of RITM.
Numbered metal plates on stakes or nailed to coconut trees near water contact sites were
seen by the villagers as an indicator that the site is hazardous in terms of schistosomiasis
infection. Idle rice fields came in last in the ranking, which is indirect proof that respon-
dents associate schistosomiasis with water contact. This is because idle rice fields in the

village are dry, with most being situated in areas that cannot be reached by irrigation wa-

 

 

 

 

 

 

 

 

ter.
Table 7.5 Knowledge on Places Where Schistosomiasis is Acquired

Free recall Prompted Don’t know Not sure Total
Rice Paddies 41.4 21.1 35.1 2.4 100%
Irrigation and Drainage Canals 25.5 39.0 31.9 3.6 100%
Main (Mainit) River 42.4 15.6 34.8 7.2 100%
Streams 72.5 4.4 22.3 0.8 100%
Creeks 67.7 7.2 23.5 1.6 100%
Idle Rice Fields 6.8 44.6 42.6 6.0 100%
Intermittent Waterways 31.9 29.4 34.0 4.7 100%

 

 

 

 

 

 

 

 

Source: Author’s survey: N = 251

Close to two-thirds of the respondents know that infection starts when a very small
worm that cannot be seen by the human eye penetrates the skin (Table 7.6). They do not
know what the cercariae look like. Many of the respondents said that cercariae enter the

human body through the pores of the skin.

115

Table 7.6 Awareness that Schistosomiasis is Acquired through
Cercarial Penetration of the Skin

 

 

 

 

Free recall 64.9%
Prompted 4.4%
Don’t know 27.5%
Not sure 3.2%

 

 

 

 

Source: Author’s survey: N = 251

Avoidance of water contact and proper disposal of human wastes are seen as im-
portant measures to avoid schistosomiasis (Table 7.7). Forty-six percent think that the use
of toilets will help prevent schistosomiasis; 45 percent think that the avoidance of bathing
in infested streams ought to do it. The idea of prevention of schistosomiasis through
regular toilet use is the consequence of past government campaigns to provide latrines to
the village. The problem is that because of their unawareness of the transmission cycle,
most villagers do not understand the links between toilet use and schistosomiasis control.
The use of rubber boots as a way of preventing schistosomiasis was mentioned by 43 per-
cent of the respondents. This is partly the result of the fact that field observers of the Re-
search Institute of Tropical Medicine (RITM) go around the village wearing rubber boots
issued by the RITM.

Very few (2.8 percent) view an improvement of farming practices as instrumental
in the prevention of schistosomiasis. This is attributable to their ignorance of the elements
and processes involved in the transmission cycle. Irrigation canals are not regularly main-
tained and regular weeding of ricefields is neglected. The result is that Oncomelania snails
are often seen on grassy sides of irrigation canals and rice paddy dikes. Thus, although
they have a vague idea that schistosomiasis may be acquired by working in ricefields, their
ignorance of the transmission process renders them helpless to do anything to prevent the

infection.

1 16
Table 7.7 Knowledge on How to Avoid or Prevent Schistosomiasis

 

 

 

 

 

 

 

 

 

 

 

Free recall Prompted Don’t know Unsure Total
Stool examination 11.6 59.0 28.7 0.8 100%
Snail control 18.3 53.4 27.5 0.8 100%
Improved farming practices 2.8 62.9 33.1 1.2 100%
Prevent bathing in infected streams 45 .0 33.1 21.5 0.4 100%
Use toilets 46.2 30.7 22.7 0.4 100%
Control stray animals 14.7 55.4 29.5 0.4 100%
Build foot bridges 35.1 38.2 26.7 100%
Provide domestic water supply 16.7 55.8 27 .5 100%
Health education 16.7 54.6 28.7 100%
Wear rubber boots 43.4 26.3 28.7 1.6 100%

 

 

 

 

 

 

 

 

Source: Author’s survey: N = 251

Fifty-three percent of the respondents treat themselves at home for ordinary ail-
ments like cough, ordinary fever, minor body aches, and superficial wounds (Table 7.8).
This behavior of self-medication is abetted by the easy availability of non-prescription
drugs. These drugs for the treatment of minor illnesses are sold in small sari-sari (variety)
stores in the village. Twenty-six percent go to the Village Health Center, which opens
once a week when a government-employed midwife holds clinic. The health center is un-
derutilized because many villagers think that it will be useless to seek treatment in a health

center where needed drugs are often not available.

117

Table 7.8 Place of Treatment for Ordinary Illnesses

 

 

 

 

 

 

 

 

 

 

 

Number %
Stay at home/self-medication 134 5 3
Village health center 66 26
Private doctor in Jaro 20 8
Hospitals or doctors in Tacloban 2 1
Local healer 13 5
Rural Health Unit in Jaro 14 6
Carigara District Hospital 1 0
Palo Schistosonriasis Hospital 0 0
Others 1 0
Total 251 100%

 

 

 

 

 

Source: Author’s survey: N = 251

Most of the respondents are willing to travel a longer distance to avail themselves
of the services of a competent doctor that will be there when needed (Table 7.9). For non-
ordinary illness and emergency cases, thirty percent of the respondents go to a private
doctor in the center of town, 25 percent go to the larger hospitals and doctors in Tacloban

City, while only 6 percent go to the Rural Health Unit (RHU) in the town center.

The diagnosis and treatment of schistosomiasis is not ordinarily within the compe-
tence of ordinary doctors. Furthermore, the drug of choice for the treatment of schistos-
omiasis is not available in drug stores. It can only be obtained from government health
centers after a determination is made that a person is positive for schistosomiasis ova. It is
therefore not surprising that ninety-two percent of the respondents go to the annual

RITM-sponsored examination and treatments at the Macanip Elementary School (Table

118

7.10). Five percent go to the Schistosomiasis Research and Training Center in Palo, while

only 2 percent go to the RHU in Jaro.

Sixty-two percent of the respondents who have at one time or another tested posi-
tive for parasite eggs said that they sought treatment after experiencing symptoms that
they perceived to be related to schistosomiasis. In the event that RITM stops its treat-
ments due to financial constraints, 96 percent of the respondents said that they will con—

tinue to submit stools for examination in Palo or the RHU in Jaro poblacion.

Table 7.9 Place of Treatment for N on-ordinary or Emergency Illnesses

 

 

 

 

 

 

 

 

 

 

 

 

Number %
Stay at home/self-medication 4 2
Village health center 0 0
Private doctor in Jaro 75 30
Hospitals or doctors in Tacloban 62 25
Can’t say (no emergency case yet) 30 12
Local healer 15 6
Rural Health Unit in Jaro 39 16
Carigara District Hospital 24 10
Palo Schistosomiasis Hospital 1 0
Others 1 0
Total 251 100%

 

 

 

 

 

Source: Author’s survey: N = 251

119
Table 7.10 Place of Treatment for Perceived Schistosomiasis Symptoms

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Number %
Stay at home/self-medication 1 0
Village health center 2 1
Private doctor in Jaro 0 0
Hospitals or doctors in Tacloban 0 0
Village school, during RITM visits 221 92
Local healer 0 0
Rural Health Unit in Jaro 4 2
Carigara District Hospital 1 0
Palo Schistosomiasis Hospital 12 5
Total 241 100%

 

Source: Author’s survey: N = 251

Schistosomiasis, although perceived as a problem, is ranked low in the hierarchy of
problems demanding attention in the village (Table 7.11). In the survey, the respondents
were asked to name the most important problems of the village. The results showed that
the respondents are most concerned about environmental sanitation, the lack of coopera-
tion and unity, and peace and order. The control of schistosomiasis in the village will in-
volve creating an awareness for the need to change behavior patterns. The majority of the
respondents had attained a certain degree of “problem awareness” in so far as schistos-
omiasis is concerned. However, the awareness has not been translated into desired action
or change in behavior. This could be the result of the perception that schistosomiasis is a
disease that is non-lethal and an effective cure is available through the annual chemother-
apy program of the government. Rosenfield (1990) succinctly states that this kind of per-
ception “... may lead the individual to decide that the disease is not serious enough to war-

rant changing behavior, and, therefore, even though the person at risk may be fully aware

120

of the etiology of the disease and its impact, he or she will continue to engage in disease
transmitting behavior...”

Table 7.11 Most Important Problems of Village

 

 

 

 

 

 

 

 

 

 

 

 

 

Number fpgsslx' % of N=212
Persons

Low income/livelihood 68 1 1.7 32.1
Peace and order 78 13.4 36.8
Food 20 3.4 9.4
Schistosomiasis 29 5.0 13.7
Health of residents 36 6.2 17.0
Roads 64 11.0 30.2
Irrigation 30 5.2 14.2
Village leadership 45 7.8 21.2
Unity 72 12.4 34.0
Environmental sanitation 98 16.9 46.2
Others 40 6.9 18.9
Total 580 100.0

 

 

 

 

 

 

Source: Author’s survey: N = 212

The survey revealed that majority of the people of the village were generally
knowledgeable about schistosomiasis. This is undoubtedly the result of the annual visits
of the research team from the Research Institute of Tropical Medicine. However, there
were gaps regarding their knowledge of how the disease is transmitted and controlled.
Although people know that schistosomiasis is acquired through water contact, they still
continued to frequent potentially infected bodies of water. The role of the snail intermedi-
ate host in the transmission of the disease is not generally known. Toilets, even if in exis-

tence, were underutilized. This is partly due to the absence of a proximate source of

121

water for flushing purposes. Many of the toilets that were built in 1986 as part of the
schistosomiasis component of the Philippine Health Development Project were destroyed
by the strong winds of a 1991 typhoon. These toilets were never repaired because of the

expense involved and the lack of a strong motivation to do so.

Although the respondents know that animals such as dogs and pigs are somehow
involved in schistosomiasis transmission, the exact role that they play remains vague to
them. Very few of the respondents in the study area knew that animals such as dogs and
pigs can act as reservoir hosts of schistosomiasis. Most respondents think that schistos-
omiasis is acquired when a person accidentally steps on the feces of infected dogs. Fol-
lowing this reasoning, they think that one way to avoid the disease is to avoid stepping on

feces of dogs and pigs or wear protective footwear.

The apathy of the respondents regarding schistosomiasis prevention efforts can be
traced to: (l) poverty, (2) the perception that schistosomiasis is not a serious disease, (3)
dependence on chemotherapy, and (4) unawareness of critical elements of the transmission
cycle. Because of their subsistence level of living, the respondents indicated that they had
no choice but to work in what they know to be potentially infected rice fields. The ab-
sence of piped water supply forces villagers to collect water for domestic use in springs
and Open dug wells in the village. Only three households were able afford hand pumps.
Because more than two-thirds of the household income of most families is spent on food
alone, the purchase of materials for the construction of latrines is low on their priorities.
The second reason has to do with the nature of schistosomiasis as a disease involving suc-
cessful parasitism. It is not usually fatal or even serious, and as Warren (1973) has
pointed out, “studies on morbidity have found remarkably little evidence of overt disease
in most areas.” Indeed, among the 10 leading problems of the village, schistosomiasis
ranked last. The third reason, dependence on chemotherapy, stems from the awareness

among the villagers that Biltricide (praziquantel) is given free every year by the medical

122

team of the Research Institute of Medicine to those who are found positive for schistos-
omiasis ova. Thus, even if they acquire the infection, they know that they can avail of free
treatment when the medical team arrives. The last reason, ignorance of critical elements
of the transmission cycle, is the reason why people do not see themselves as agents that
contribute to the perpetuation of the disease. Thus, children are not trained about safe
defecation habits and adults are not predisposed to construct toilets. Similarly, ignorance
of the role of snails in the transmission cycle is the reason why villagers have not given

snail control activities the required high priority.

Chapter 8

CONCLUSIONS AND RECOMMENDATIONS

By using the model of the schistosomiasis transmission cycle as a heuristic device,
this study has identified the elements involved in the transmission cycle of Schistosomiasis
japonicum in the village and analyzed how each might contribute to the persistence of the
disease. The inferences that were made in this study about the relationship between per-
sistence of the disease in the village and the elements of the transmission cycle are based
on previous research on each of these elements. Although data limitations preclude a
more assertive statement regarding correlation and cause and effect relationships, this
study has shown that human schistosomiasis infection in Macanip is associated with haz-
ardous human behavior, favorable environmental characteristics, presence of snail inter-
mediate hosts, and presence of animal hosts. The rest of this chapter presents this study’s
conclusions and recommendations with respect to the postulated relationships that were

presented in Chapter 3.

The transmission of schistosomiasis is associated with favorable environmental
characteristics such as slow—flowing water, even distribution of rainfall

throughout the year, and shade-providing vegetation.

The physical environment of the large lowland plain in which the village lies pro—
vides preconditions for the persistence of Schistosomiasis japonicum infections. The even
distribution of rainfall throughout the year guarantees the presence of numerous perennial,

slow-moving waters in which the amphibious 0. h. quadrasi can persist. The almost fiat
123

124

topography guarantees that worm eggs, hatched miracidia and cercariae are not washed
away by increased water flow velocity. The absence of roads and dry trails in the east and
southeast of the village means that residents of the hamlets have to traverse wet trails, ini-
gation canals, and streams to be able to reach the “poblacion” and from there the town
center of J aro. This increases opportunities for contact with infected water. Rivers,
creeks, and springs are places for washing and bathing and are sources of domestic water

supply. Inigation ditches and small water impoundments are potential snail habitats.

The even distribution of rainfall and the minimal gradient of the land allows the
formation of aquatic environments in which humans, animals, the snail host, and the
parasite continually converge to perpetuate the schistosomiasis disease system in the vi]-
lage. These environmental characteristics have spawned a rice cultivation system that
provides an abundance of opportunities for farmers and their families to be exposed to

potentially infected waters.

The timing of treatments in Macanip may have to be re-studied so as to avoid the
period of highest rainfall. Annual screening and treatment occur early in the first quarter
of each year, which overlaps with the maximum rainfall period in the area. Snail infection
data gathered in human water contact sites in the village show that snails have a higher
rate of infection during the planting season when rainfall amounts are higher. Previous
studies in Leyte have shown that the greatest danger of infection to mammalian hosts oc-
curs during periods of high rainfall. The treatment of people who are infected or rein-
fected during this period may be ineffective because the drug of choice, praziquantel, has
little effect against immature schistosomes (Jordan and Webbe, 1993). For community
treatment with praziquantel to achieve its intended maximum impact, the drug should be
given when transmission is low or absent (Sturrock, 1993). The result of the on-going

water contact studies would provide a guide regarding the timing of the treatments.

125

Although the annual treatments appear to be successful in reducing the worm bur-
den in the population, schistosomiasis still persists because of the high probability of rein-
fection in the many waterways and rice paddies of the village. The strategy should include
measures to reduce human exposure to potentially infected water. My analysis of water
contact data furnished by RITM showed a high frequency of water contacts that are of
very short duration. This is primarily due to the large number of waterways that must be
forded when going from one point of the village to another. In these situations, the dimi-
nution of the probability of infection by the short duration of water exposure is offset by
the high frequency of water contact during the day. To reduce the potential for infection
or reinfection, the villagers should increase the number of foot bridges at canal and stream
crossings. Materials for these foot bridges such as coconut tree trunks abound in the vil-

lage.

The transmission of schistosomiasis is associated with contamination of water

bodies by human feces.

This study has shown that schistosomiasis is maintained in part through contami-
nation of water bodies by ova-bearing human feces. This is due to the absence of toilets in
more than two-thirds of the houses in the village. This situation is aggravated by the fact
that the availability of a toilet does not mean that it is always used. One factor that works
against toilet use is the inconvenience of collecting water for flushing from a water source
that may be some distance from the dwelling. Small children are prone to defecate wher-
ever it is convenient. This could be anywhere from the house front and backyard to the
nearest irrigation canal. One would therefore expect that schistosome eggs that are con-
tributed by children would be distributed according to the settlement pattern of the village.
The adult need for concealment while defecating results in a more focal distribution of

schistosome eggs contributed by adults. In both cases, the schistosome ova eventually are

126

washed into the dense network of waterways of the village. This process is facilitated by

frequent rainfall that blankets the village.

Changing the defecation habits of the people in the village would be a very difficult
task. Previous studies have shown that reducing environmental contamination through
basic sanitation such as latrines has had poor results (W ebbe, 1988). It seems that a sig-
nificant change in basic sanitation habits of the people can only happen when the general
level of economic prosperity in the village is increased. People who are pre-occupied with
the daily struggle to make a living at the subsistence level will not have the time and luxury
to think of building and using nice household conveniences like toilets. Higher levels of
education that are a part of economic prosperity would also mean a higher rate of usage of

toilets.

Community action could also be another approach to persuade people to use toi-
lets. Based on prior experience in the village, no amount of government-supplied toilets
can make the people use latrines unless the impetus to do so comes from the village itself.
The village has already proven that it is capable of effective community action when it
won a nationwide contest in 1957 for being the cleanest village in the country. The suc-
cess of this community action was attributed to the leadership of a village school teacher
who mobilized the school children and their parents to clean up and beautify the village.
Thus, community action to encourage the use of toilets could be pursued by any of the
local non-political organizations like the Parent-Teachers Association and the Farmers’

Association.

The transmission of schistosomiasis is associated with agricultural practices

that favor the 0. quadrasi population.

The persistence of the O. quadrasi population in the village is partly due to the
poor or non-maintenance of irrigation canals. I observed that snails prefer the grassy sides

of dikes in rice paddies and irrigation canals. In canals that are not maintained at all and

127

which are therefore covered with grass, snails could be seen clinging to stalks and blades
of grass. The snails use the grass and overhanging vegetation to protect themselves from
higher surface temperatures during midday. In instances where the velocity of water
flowing through irrigation canals becomes intolerable, the snails retreat and cling to the

grassy sides and walls of the canal.

The elimination of the snail intermediate host appears to be the only measure that
would lead to complete disappearance of schistosomiasis in the village. This is because it
would halt the chain of infection in both the human host and the animal reservoir. Mol-
lusciciding, environmental modification, and improved agricultural practices are some of
the options that are available. The slow velocity of water flow in the meandering streams
in the village might pose a problem to snail control efforts. The study of Yasuraoka
(1989) in Northern Bohol discovered that although combined vegetation removal and
mollusciciding appeared successful in eliminating and reducing the snail population in most

swamps, it did not yield satisfactory results in meandering streams.

To make the irrigation canals of the village unsuitable for the snail host, the local
irrigation association or farmers’ association should look into the feasibility of canal lining
and improved channel design. Aside from providing more water for crops, canal lining
results in higher water velocities and less aquatic vegetation which in turn would result in
less snails. With the help of engineers form the National Inigation Administration, farmers
could improved channel design of canals. Since changing the gradient could be impracti-
cal, an alternative would be to make the channel cross-section narrower and deeper

(W ebbe, 1988).

The transmission of schistosomiasis is associated with hazardous water contact

behavior.

The lack of a safe domestic water supply has led to hazardous water contact be-

havior that contributes to the persistence of infection in the village. Young children are

128

given the task of collecting drinking water in open dug wells and springs. They often play
in the water while going about this task The task of water collection is usually done
twice a day, once in the morning and another in the late afternoon. Water contact obser-
vations showed that during the harvest season, drawing water and playing or swimming in
the water were activities that peaked in the late afternoon. Water contact in the afternoon
is more risky because by that time most of the cercariae would have swarmed out from

infected snails.

Next to playing in the water by children, water contact that is related to work in
the rice fields carries with it a high risk of acquiring the infection. Rice farmers of all age
groups have the longest duration of water exposure. On the average, rice paddy work
lasts for 53 minutes per exposure, and there can be several exposures in a day. Among
rice farmers, hired laborers and those who specialize in construction and maintenance of
dikes face higher risks. These people stay in the rice paddies longer during the start of the
planting season. Dike construction and maintenance laborers are at high risk because they
work the part of the rice fields that are favored locations of O. quadrasi snails. High in-
fection risks also occur among farmers who irrigate their fields at night. Because of the
limited amount of irrigation water, these people have to wait until the evening for their
turn to irrigate their fields. Again, they face higher risks because of the presence of a

higher number of cercariae in surface waters at this time of the day.

The persistence of schistosomiasis is associated with inadequate knowledge

about the schistosomiasis transmission cycle.

Serious gaps exist in so far as the villagers’ knowledge of the schistosomiasis
transmission cycle is concerned. Although most of the people who were interviewed
knew that schistosomiasis is acquired through water contact, they were unaware of the

role of animal reservoirs and snail intermediate hosts. Furthermore, they were unaware of

129

the concept of a schistosomiasis transmission cycle. Schistosomiasis persists in part be-

cause people, by their lack of knowledge, ignore the zoonotic aspects of the disease.

The option of mass chemotherapy and its acceptability to the community must be
studied. Experience has shown that unless this strategy is thoroughly explained to the
community, it may encounter some resistance in the village. In the water contact study
area where mass chemotherapy is being implemented in connection with studies of rein-
fection, this author observed that a number of people refused to participate because they
wanted to make sure that they were positive to schistosome ova first before taking
praziquantel tablets. Results of the screening were delayed and could not be relayed to the

study population.

Health authorities should work with villagers in coming up with a sustained control
strategy that will be canied out through the primary health care system. This approach
involves stimulating the active involvement of the community to assist schistosomiasis
control personnel in the planning, implementation, and monitoring of control programs.
The primary health care worker will play a critical role by collaborating with the control
team in the diagnostic and treatment surveys and by assisting in including schistosomiasis

control in health education programs. (WHO, 1985).

The strategy of selective population chemotherapy in the village may have to be
reassessed by planners and implementors of the control program. Previous studies have
demonstrated the possibility that lightly infected individuals may not be excreting eggs at
all at the time of screening. These people will be missed by targeted chemotherapy that
selects for treatment only those people with ova in their stools. The problem is aggra-
vated by individuals who do not participate in the annual screening and treatment by
RITM. These people have the potential of maintaining the transmission in the village even

if chemotherapy is successful in all individuals who underwent screening.

130

The persistence of schistosomiasis is associated with the inability of the control

program to interrupt the zoonotic cycle of the parasite.

Macanip has a high population of pigs and dogs that can act as reservoirs of infec-
tion. Both of these animals are allowed to roam freely in the backyards of houses. It is
therefore common to see the animals’ feces lying around the yards of houses. These are
washed down into nearby canals and streams when it rains. Although the pig population
suffers a precipitous drop in June in connection with the village fiesta, the reduction in

transmission would probably be minimal because the fiesta coincides with the dry season.

The role of field rats in the maintenance of transmission in the village has been
virtually ignored by the present control program. This is unfortunate because previous
studies have demonstrated that next to man, the field rat is the most important host of
Schistosomiasis japonicum in the area (Hinz, 1985). The schistosome disease prevalence
in field rats is high throughout the year -- from 70% to 95%. Compounding the problem
is the fact that field rats multiply rapidly, they obtain their food from ricefields, and they

defecate several times in 24 hours (Cabrera, 1976).

The rat population is estimated to be 40 times the human population in the village,
which gives them a very high potential for maintaining the infection in the village. Thus,
even if there is a 100% compliance by villagers in both mass chemotherapy and the use of
toilets, schistosomiasis transmission will still be maintained through the field rat. In the
event that annual screening and chemotherapy in the village is discontinued for any reason,

humans will most certainly be reinfected.
The persistence of schistosomiasis is associated with poverty.

The statement that schistosomiasis is a disease of the rural poor is valid in
Macanip. Poverty is the reason why people cannot build their own domestic water supply.

Poverty is also the reason why people are not able to acquire a higher level of education

131

that will make them realize the necessity of using toilets for defecation. Poverty in the
village is revealed by the fact that 70% of the households had a negative net household
income, meaning that household expenditures exceeded regular household income. They
compensate for this deficit by borrowing money from relatives or rendering personal
services, which may increase their infection risk, in return for money or food. An example
of this income-supplementing activity is prendis in which an individual weeds a farmer’s
rice field during the growing season for free in return for the privilege of participating in
the harvest and getting a share of the rice yield. Another widely used practice to supple-
ment the food on the family table is night fishing in which the farmer wades through rivers
and streams carrying a lamp that attracts fish. This practice exposes the individual to a
high risk of infection because in the early evening cercariae from infected snails would be

swarming in streams in search of mammalian hosts.

The transmission of schistosomiasis is associated with the absence of a safe do-

mestic water supply.

As previously noted, only 16 percent of the households draw their drinking water
from artesian wells or privately owned manual handpumps. The rest of the households get
their drinking water from springs and open dug wells. The task of washing clothes bring
women in contact with the Mainit River and other streams two to three times per week.
The potential for infection brought about by a longer duration of exposure is mitigated by

the fact that this activity is done in the morning when infection risk is lower.

Providing safe water supplies in the village will give added protection, especially to
women and children. Although set in a different environment and culture, some lessons
may be drawn from the St Lucia project in the Caribbean. The results of the project indi-
cated that improved domestic water supplies reduced schistosomiasis transmission. After
installation of domestic water supplies, water contact studies showed a 97 percent reduc-

tion in the number of persons utilizing river water for all purposes. In addition, because of

132

decreased human contact with river water fewer snails were infected in the project area
(Jordan, Woodstock, Unrau, and Cook, 1975). The Riche Fond studies in St. Lucia have
demonstrated that when health education and adequate alternative water sources are made
available, customs can be changed and children can be taught to stay out of rivers. Thus.
the number of hand pumps and artesian wells in the Macanip needs to be increased to give
people better access to safe water. Public laundries should be built where women can
wash clothes and socialize at the same time. If there is a free free-flowing supply of spring
water , shallow pools could be built in these public laundries wherein children who ac-

company their mothers can bathe and play.

The results of this study suggest that schistosomiasis infection may be significantly
reduced by supplementing the annual chemotherapy conducted by RITM with locally-
initiated programs to improve agricultural practices and providing safe water supplies.
The evidence has shown that the age and occupational groups that are engaged in rice
farming are at the greatest risk. Water contact observations indicate that these groups

may be acquiring the infection in ill-maintained irrigation canals and ricefields.

Existing institutions in the village need to be tapped to control schistosomiasis.
The most organized, active and financially able organization in the village that is in a posi-
tion to provide local counterparts to the national government’s schistosomiasis control
efforts is the Samahang Nayon (Farmer’s Association). What needs to be done is to im-
press upon the members of this group that economic upliftrnent and schistosomiasis con-
trol is attainable through improved farming practices such as regular weeding of ricefields
and maintenance of irrigation canals. These practices will make the ricefields and iniga-

tion canals unsuitable environments for the snail host.

BIBLIOGRAPHY

BIBLIOGRAPHY

Abbot, R.T. 1946. “The Egg and Breeding Habits of of Oncomelania quadrasi Mlldffi,
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APPENDIX

MACANIP SCHISTOSOMIASIS SURVEY

(The author tormuated, pre-tested, aid administered this interview
schedule to 251 respondents between February andJune 1993.)

Good moming/aftemoon/evening. My name is Renato Cerdefia. I am presently undertaking a
study of schistosomiasis in Macanip. I will be interviewing a sample of people in your barangay.
You have been chosen as one of the respondents. I will appreciate your cooperation. Rest
assured that your responses will be held in the strictest confidence. Maupay nga aga/kulop/gab-i
ha iyo. Ako hi Renato Cerdeiia. Hapag kayana nagkakamay-ada ako hin pag-aram han
schistosomiasis dinhi ha Macanip. Mamamakiana ako hin mga tawo dinhi ha iyo baranga y ug
usa la han akon napili. Ug an imo kooperasyon in akon gin/alauman. Pagtapod Ia nga an aton
pagiistoryahan in aton Ia ug din’ magawas ha publiko.

Block 1: Identifying Information

Respondent Number
House Number
Zone Number
Name of Interviewer
Name of interpreter
Place of interview
Date of interview
Time started
Time finished

0 Language of interview

 

 

 

 

 

 

 

 

 

d-l—L—L-L-L—l-L-A—L
aromxraatnaoom'a

 

Block 2: Background data

2.1 Name

 

2.2 Gender
_O_female _1_ male

2.3 Civil Status Inasaw-an Ira ba?
_0_ single _1_ married _2_ widow/widower _3_ separated

2.4 How old were you on your last birthday? Pera an imo idad han imo guioorhe-e nga
birthday?

CODE EXACT NUMBER OF YEARS

2.5 Where were you born? Diin ka katawo?

_0_ same barrio

_+1_ other barrio, within town

_2_ another town, within the province

_3_ other province, within Island of Leyte or Eastern Visayas
___4_ other province, outside Island of Leyte or Eastern Visayas

2.6 Have you moved within the last five years? Ha sakub han Iima katuig, binmalhin lea ba
hin pag-okoy o pareho man diin ka tikang san-o ka pag-okoy dinhr‘?

0_ no
yes
1 same barrio

_2_ other barrio, within town

140

 

2.7

3.1

3.2

3.3

3.4

3.5

3.6

141

_3_ another town, within the province

_4_ other province, within Eastern Visayas (e.g. Samar provinces,
Southem Leyte)

_5_ other province, outside Eastern Visayas

What is the highest grade that you have m? Ano nga grado an imo natapos?

_0_ none _5_ high scth graduate
_1_ primary (Grade 1-2) _6_ part college

_2_ secondary (Grade 3-4) _7_ college graduate
_3_ intermediate (Grade 5-6) _8_ vocational

_4_ high school (1 -3)

Block 3: Living Conditions

Is your home An imo ba inookyan nga bala y, imo ba kalugaringun, plityado, o kun
nalungun ka la?

0 your own _1_ rented

2_ shared with others

Do you own the land on which your home is built? Kalugaringun mo ba inin tuna nga imo
guinbalayan?

_0_ no 1 yes

Construction materials of dwelling unit Anu nga materyales an imo ginamit pagbalay

_0_ cogon/bamboo _2_ wood/concrete

_1_ wood _3_ scrap/barong-barong

What fuel do you use for cooking Ano an imo ginagamit nga paagi (sungo) ha pagluto?
_0_ electricity _2_ liquid petroleum gas

_1_ kerosene _3_ wood and coconut shells

Do you have a toilet May ada ba niyo kasilyas?
0 none PROCEED TO QUESTION 3.6

yes PROCEED TO QUESTION 3.9

_1_ pit latrine, water-sealed, unlined septic tank

_2_ pit latrine, water-sealed, septic tank lined with bamboo or wood
_3_ pit latrine, water-sealed, septic tank lined with used drum

_4_ pit latrine, water-sealed, septic tank lined with cement

_5_ antipolo

_6_ pit privy
Why don't you have a toilet Kay ano nga waray kamo kasilyas’?
_0_ foul odor inside toilet _5_ high cost of materials
_1_ lot of work to dig pit/tank _6_ not interested

_2_ frequent transfer of residence
_3_ destroyed during past typhoon (November 1991)
_4_ more convenient to defecate in the open/among bushes

142

 

 

 

3.7 Where do you defecate Diin kamo na-uro?
__0_ banks of Mainit River _3_ within banana tree clusters
_1_ within bushes _4_ irrigation canals
_2_ banks of streams (specify)

3.8 How far is your usual defecation area from your house Ana kahirayo iton imo kaudganan
nga pag-uro tikang ha imo balay?
_0_ 25 meters or less _2_ 26 to 50 meters
_1_ 51 to 100 meters _3_ more than 100 meters

3.9 What is your main source of water for drinking and cooking? IF SOURCE IS
POTENTIALLY INFECTED WATER. ASK RESPONDENT TO SPECIFY FREQUENCY
AND DURATION OF WATER CONTACT PER DAY Diin kamo naalog hin tubig para
pag-inom ngan pagluto (Mainit, busay, irrigation canal, sapa) IPAKIANA ITON KAIHA
HITON KAHULOS DIDTO HA TUBIG NGAN KUN PIRA KABESES.

H20 Contact Frequency Duration

_0_ Mainit river _ . _ __
_’_ Stream (specify) __ _
_9_ Irrigation canal _ __
_10__ spring __ __ __
_1 1__ communal water system
_12_ artesian well/manual handpump
_13_ open dug well __ __
_14_ rain water storage tanks __ __
_15_ other (specify)

" Streams: (1) Taytay (3) Morokborok (5) Sapa (7) Tuod

(2) Mamlag (4) Hagosais (6) Hambabalod (8) Badiang

Frequency: (0) once/day (2) 3x+/day (4) 2x/week (6) once/month

(1) 2x/day (3) once/week (5) 3-4x/week (7) 2x/month

Duration: CODE NUMBER OF MINUTES

3.10

What is the source, or where do you (or your wife) launder your clothes IF SOURCE IS
POTENTIALLY INFECTED WATER, ASK RESPONDENT TO SPECIFY FREQUENCY
AND DURATION OF WATER CONTACT PER DAY) Diin kamo pamumunak? (Mainit,
busay, irrigation canal, sapa) IPAKIANA ITON KAIHA HITON KAHULOS DIDTO HA
TUBIG NGAN KUN PIRA KABESES?

H20 Contact Duration

_0_ Mainit river
_'_ Stream (specify)
_9_ Irrigation canal
_10_ spring
_11_ communal water system
_12_ artesian well/manual handpump
_13_ open dug well

_14_ rain water storage tanks

_15___ other (specify)

 

11
5
8
<

 

* Streams: (1) Taytay (3) Morokborok (5) Sapa (7) Tuod

(2) Mamlag (4) Hagosais (6) Hambabalod (8) Badiang

143

Frequency: (0) once/day (2) 3x+/day (4) 2x/week (6) once/month
(1) 2x/day (3) once/week (5) 3-4x/week (7) 2x/month

Duration: CODE NUMBER OF MINUTES

3.11 What is the source / where do you (and other family members) bathe? IF SOURCE IS
POTENTIALLY INFECTED WATER, ASK RESPONDENT TO SPECIFY FREQUENCY
AND DURATION OF WATER CONTACT PER DAY) Diin kamo nakarigo? (Mainit,
busay, irrigation canal, sapa) IPAKIANA ITON KAIHA HITON KAHULOS DIDTO HA
TUBIG NGAN KUN PIRA KABESES?

H20 Contact Frequency

_1_ Mainit river

_*_ Stream (specify)
9 Irrigation canal

_10_ spring
_11_ communal water system
_12_ artesian well/manual handpump
_13_ open dug well

_14_ rain water storage tanks
_15_ other (specify)

 

O
t:
6.
3

 

* Streams: (1) Taytay (3) Morokborok (5) Sapa (7) Tuod
(2) Mamlag (4) Hagosais (6) Hambabalod (8) Badiang

Frequency: (0) once/day (2) 3x+/day (4) 2x/week (6) once/month
(1) 2x/day (3) once/week (5) 3-4x/week (7) 2x/month

Duration: CODE NUMBER OF MINUTES

3.12 What is the source, or where do you wash your farm animals, it any? IF SOURCE IS
POTENTIALLY INFECTED WATER, ASK RESPONDENT TO SPECIFY FREQUENCY
AND DURATION OF WATER CONTACT PER DAY Diin ka paghuhugas han imo ig-
uruma nga hayop? (Mainit, busay, irrigation canal, sapa) IPAKIANA ITON KAIHA
HITON KAHULOS DIDTO HA TUBIG NGAN KUN PIRA KABESES?

H20 Contact Frequency Duration

_1_ Mainit river
_'_ Stream (specify)
_9_ Irrigation canal
_10_ spring
_11_ communal water system
_12_ artesian well/manual handpump
_13_ open dug well

_14_ rain water storage tanks

_15_ other (specify)
" Streams: (1) Taytay (3) Morokborok (5) Sapa (7) Tuod
(2) Mamlag (4) Hagosais (6) Hambabalod (8) Badiang

Frequency: (0) once/day (2) 3x+lday (4) 2x/week (6) once/month
(1) 2x/day (3) once/week (5) 3-4x/week (7) 2x/month

Duration: CODE NUMBER OF MINUTES

3.13 What is your approximate expenditure for Ha imo pagkarkulo, pira an imo nagagastos
para han masunod nga mga butang

 

 

 

. food pagkaun-pagsura

144

Daily Weekly Monthly Yearly

. health/medicine medisina

1

2

3. clothing panapton
4. household utensils
5. electricity/lighting pagsuga
6. education pagpaiskuwila
7. Ieisure/socials paglibang-Iibang
8. reading materials barasahun
9. transportation transportasyon
10. savings hinipos

4.1

4.2

4.3

4.4

What is

 

 

 

Block 4: Livelihood and Income
your present occupation or farmer status? Ha pagkayana, ano iton imo

kabutangan komo mag-umma?

_0_
1 _
_2_

_3

_4_

5_

tanner-owner may kalugaringon nga umhanan
farrner-Ieaseholder nagplipliti

farmer-tenant saop

farmer-laborer magpasunrhol

combination of above kombinasyon han nga tanan
others

Do you own rice land May kalugan'ngon ka nga hagna?

__0_ no

 

yes
_1_ less than or equal to 0.5 hectares
_2_ more than 0.5 but less than 1.0 hectare
__3 more than 1.0 hectare

Do you own coconut land May kalugaringon ka nga Iugitan?

0

 

no
yes

_1_ less than or equal to 0.5 hectares
_2_ more than 0.5 but less than 1.0 hectare
_3 more than 1.0 hectare

Do you own land planted to corn and rootcrops

_0_

 

no

yes

_1_ less than or equal to 0.5 hectares
_2_ more than 0.5 but less than 1.0 hectare
_3 more than 1.0 hectare

FOR ANSWERS TO QUESTIONS 4.5, 4.6 & 4.7, FILL OUT THE APPROPRIATE COLUMNS IN
THE TABLE ON PAGE 10. COLUMNS 1-3 OF THE SAME TABLE SHOULD BE FILLED OUT
BEFORE THE INTERVIEW. GET DATA FROM CENSUS LIST.

4.5

4.6

4.7

145

Who among your household members earn a living? Hin-o ha imo miyembro hin
pamilya in may pakabuhf?

What is the primary (and secondary, if any) occupation of each of these members who
earn a living? Ano iton ira primero nga pakabuhi ngan hiton iba pa nira nga
pinagkakakitaan?

What is the approximate income gained in the practice of these occupations? Ha imo
panhunahuna, pira iton ira kinikita tikang hini nga ira pakabuhl?

IF RESPONDENT MENTIONS CROP FARMING AS PRIMARY OR SECONDARY
OCCUPATION, ASK HIM/HER TO ANSWER THE QUESTIONS
4.8 TO 4.10.

4.8

4.9

4.10

4.11

4.12

How much is the total production cost in the cultivation of your primary and secondary
crop in one year”? Pira iton imo ginagasto ha pag-uma kada tuig pareho man an imo
nagagasto hadron iba pa nimo nga bumhaton ha pag-uma? CODE AMOUNT PER
CROPPING IN THE CASE OF RICE AND AMOUNT PER QUARTER IN THE CASE OF
COPRA. IF RESPONDENT IS A FARM LABQBEB, PROCEED TO QUESTION 4.11

rice (_ primary _ secondary)
harrowing and plowing pag-arado/pagsumd
cleaning/construction of dikes panha wan/panagaytay

transplanting pagganl/pagtanum

seeds gahi

food paglaun

farm inputs, e.g. fertilizer,

pesticides, herbicides

 

copra ( _ primary _ secondary)

climb and harvest coconuts panaka
remove coconut husk pagbunot
food pagkaun

others

 

 

What rice varieties do you plant?

_0_ high-yielding, certified seeds
_1_ high-yielding, 2nd or 3rd generation seeds
_2_ native/local varieties

 

 

Where do you source your capital for crop production? Diin ka nakuha hin panggasfos
hiton imo pagtrabaho ha imo umhanan?

_0_ local lenders _3_ farmers cooperative
_1_ rural bank ___4__ self-financed
_2_ landowner (in case of tenants) _5_ others (specify)

What are your main activities as a laborer? Komo maguruma nga nagpapasuhol, ano
iton imo trabaho kun ikaw an nagpapasuhol?

_0_ plowing and harrowing _3_ transplanting
_1_ weeding _4 combination of above

_2_ construction and maintenance of dikes and irrigation canals

What animals do you own and how many Ano ngan pipira iton imo mga hayop? Pipira
iton hinigtan ngan kinudal ngan pipira iton IayaW?

 

4.13

4.14

5.1

146
Total Number loose Number tied or in pens

 

chicken
goats
turkeys
cows

ducks
none

 

Do you engage in night fishing? If yes, please specify usual time and duration per week
Tigpanulo ka ba hin isda o bako, ngan nakakapira kabeses hiton usa ka semana ngan
ano kaiha?

 

 

 

 

_0_ no
yes
frequency
usual time
duration
Frequency: (0) daily (2) 3-6x/week (4) once/month

(1) 2x/week (3) once/week (5) 2x/month
Usual time: USE 7:00 PM FORMAT

Duration: (0) 1 hour or less (2) >2 to 3 hours
(1) >1 to 2 hours (3) >3 hours

Do you usually secure irrigation water at night? Nagpapatubig ka ba hiton imo hagna
kon gab-i ngan kon ikaw in nagbubuhat hini pira kabeses hiton usa kasemana ngan ano
leiha?

 

 

 

 

no
yes
frequency
usual time
duration
Frequency. (0) daily (2) 3-6x/week (4) once/month

(1) 2x/week (3) once/week (5) 2x/month
Usual time: USE 7:00 PM FORMAT

Duration: (0) 1 hour or less (2) >2 to 3 hours
(1) >1 to 2 hours (3) >3 hours

Block 5: Health-seeking behavior

Where do you go for consultation or treatment of ordinary illnesses like colds, coughs,
fever, diarrhea, and small wounds? Hin-o imo dinadaop para magpakonsulta o
magpabulong kun naglekamay-ada ka sala’t sugad hin hiranat, ubo, trangleso, pag-uro-
uro o gudti nga samao?

_0_ stay at home/self-medication _4_ local healer
1_ barangay health center _5_ RHU in Jaro town proper

147
_2_ Private doctor in Jaro _6_ Carigara District Hospital
_3_ hospitals or doctors in Tacloban _7_ Palo Schisto Center

5.2 Where do you go for treatment of non-ordinary or emergency cases? Diin ka
napabulong kun nagkakamay-ada ka din' ordinaryo, grabe, o kun apeke nga pagbati hin

sakit ug panhinabuha Iawas?

_0__ stay at home/self-medication _5_ local healer

_1_ barangay health center _6_ RHU in Jaro town proper
_2_ Private doctor in Jaro _7_ Carigara District Hospital
_3_ hospitals or doctors in Tacloban _8_ Palo Schisto Center

_4_ cannot say (no emergency ease yet)

5.3 Where do you go for consultation and treatment of what you suspect to be symptoms of
sch istosomiasis? Diin ka napala‘ana o napabulong kun ha imo kalugaringon natahap ka
nga may ada ka sakit nga schistosomiasis?

_0_ stay at home/seIf-medication _5_ local healer

_1_ barangay health center _6_ RHU in Jaro town proper
_2_ Private doctor in Jaro _7_ Carigara District Hospital
_3_ hospitals or doctors in Tacloban _8_ Palo Schisto Center

_4_ Macanip Elementary School, during visitations of RITM doctors

5.4 How did you learn that you had schistosomiasis? Ano nga paagi nga nahabaro ka nga
may ada ka sala't nga schistosomiasis?

_0_sought treatment RITM/RHU/Palo Schisto Center after experiencing symptoms
dida han kahuman mo pagpakonsulta ha RITM/RHU-Jaro/Palo Schisto Center
ug pag-abat hin pangiIaI-an hin ka may sakr't nga schistosomiasis

_1_submitted stools to RITM/RHU/Palo Schisto Center even without experiencing

symptoms kahuman mo paghatag hin baya para maeksamen ha RITM/RHU-
Jaro/Palo Schisto Center bisan wara y ka pagtahap hin pagkamay-ada sakit nga
schistosomiasis

5.5 In case RITM cannot continue its stool examinations and treatments because of budget
limitations, will you go to the RHU in Jaro or Palo Schisto Center every year for stool
examinations and/or treatment? Pananglitan diri na magpada yon hin pamulong hin
schistosomiasis an Film tungod hin mga rason, mapaeksamen ka ba 0 mapabulong ha
RHU ha Jaro 0 ha Palo Schisto Center kada tuig?

_0_ no _1_ yes

5.6 Are you participating (meaning submitting stools and/or taking Biltricide) in the program
of treatment of schistosomiasis by RITM? In what years did you participate? Naapi Ira
ba hin pagpa-eksamen ha ba ya a pag-tomar hin Biltricide hiton kanan RI TM pamulong
hiton schistosomiasis, ngan kakan-o nga tuig?

_o___ no (PROCEED TO QUESTION 5.7)
_1_ yes (PROCEED TO QUESTION 5.3)

_1 982 _1 986 _1 990
_1 983 _1987 _1991
_1 984 _1 988 _1 992
_1 985 _1 989 _1993

TO INTERVIEWER: Which of the following best describes the respondent's recall of the
instances (years) of stool submission and treatment?

5.7

5.8

5.9

148

_0_ remembered easily

_1_ remembered, but with some difficulty
_2_ remembered, but with great difficulty
_3_ did not remember years

Why are you not participating? (PROCEED TO 5.10) Kay ano nga waray ka umapi hin
nagpabulong?

_0_ I have not experienced any of the known symptoms of schistosomiasis

1_ l was alienated because of what I perceive to be preference given to non-
Macanip residents in the treatment of cases

_2_ lam not interested in treatment

_3_ l was not properly informed about the program

_4_ I am too busy

I go to other places/doctors for treatment

_5_ local healer

_6_ barangay health center

_7_ RHU in Jaro town proper

_8_ Private doctor in Jaro

_9_ Carigara District Hospital

_10_ Palo Schisto Center

_11_ hospitals and/or doctors in Tacloban

 

Did you submit stools to RITM for examination last year and this year (1992 and 1993)?
Nag-hatag ka ba hin baya para maeksamen han tuig 1992 ug 1993?

1992 _0_No _1_Yes
1993 _0_No _1_Yes

Did you take medicine (Biltricide) last year and this year? Nag-tomar ka ba hadton 1992
ug 1993‘?

1992 _0_No _1_Yes
1993 _0_No 1_Yes

FOR THE FOLLOWING QUESTION, FILL OUT THE APPROPRIATE COLUMNS IN THE
TABLE IN PAGE 10. INDICATE YEAR/S (DATES) OF STOOL SUBMISSION AND/OR
TREATMENT.

5.10

6.1

Since 1982, in which years have each of your household members submitted stools and
/ or been treated with anti-schistosomiasis drugs? Tikang hadron 1982, hin-o han imo
miembro han pamilya in nagpaeksamen hin baya ha FII TM ngan hin-o ha ira in
nagpabulong hin schistosomiasis ug ano nga tuig?

Block 6: Knowledge about schistosomiasis

Please tell me your your sources of information about schistosomiasis. Diin ug ha
kankana y ka habaro nan sakit nga schistosomiasis?

_0_ individual approaches _3_ mass media
_1_ community organization or group process

149
ACQUISITION

SITES OF ACQUISITION

6.2 In which places does one acquire schistosomiasis? Diin nga Iugar in usa nga tawo
nakakakuha hin sala’t nga schistosomiasis?

free recall prompted don't know notsure
(0) (1) (2) (3)

rice paddies

irrigation and drainage canals
Mainit River

streams

creeks

idle rice fields

intermittent waterways

 

 

MODE OF ENTRY

6.3 How does "schistosomiasis“ (cercariae) enter the body? Paunan-o nasulod an
schistosomiasis ha aton Iawas?

free recall prompted don‘t know notsure
(0) (1) (2) (3)

skin penetration

TRANSMISSION

6.4 Can schistosomiasis be transferred directly from one person to another? Natapon ba an
sakit nga schistosomrasis ha iglcasi tawo pareho hin tuberculosis

_0_no _2_don‘t know
_1_yes _3_not sure
_4_not directly, but through a transmission cycle

ELEMENTS OF TRANSMISSION CYCLE

6.5 What are the elements of the transmission cycle? Ano nga mga hayop o mananap diin
puwede omokoy o mabuhi an schistosomiasis?

free recall prompted don‘t know notsure
(1) (2) (3)

parasitic worm

tiny snails

animals (pigs, rats, dogs, carabaos)
humans

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CONTROL

6.6 What should one do to avoid or prevent schistosomiasis? Ano an mga sadang naton
buhaton basi Ia'ta din' masakit hin schistosomiasis?

free recall prompted don't know notsure

(0) (1) (2) (3)

have your stools examined

snails should be controlled

improved farming practices

prevent people especially children from
bathing in infested streams

use toilets

control stray animals

build foot bridges over canals and
creeks

provide adequate water supply for
bathing, laundering and safe
drinking water

health education so that people can
protect themselves

wear rubber boots

6.7 How do you get newsfrnfonnation about affairs concerning Macanip, Jaro & Leyte and
the rest of the Philippines? Ano nga mga bagayan iyo nakukuhaan hin inporrnasyon hin
bisan ano nga panhinabo ha sakob han Macanip, Jaro, Leyte, ug ha bug-cs nga
Pilipinas?

Macanip Jaro & Leyte rest of the Phil.

(0) friend/neighbor

(1) unit leader

(2) elected barangay officials

(3) town crier

(4) municipal, provincial, national officials
or employees

(5) radio

(6) television

(7) newspapers

Block 7: Community ratlng
7.1 In your opinion, is your barangay, when compared to other barangays Kun an iyo
barangay, tending han iba nga barangay, ha imo pagsabut, ano an iyo kabutangan (ha
pagpakabuhi)?

_0_ more prosperous mauro-upay
1_ less prosperous din' maupay

2_ of about average prosperity maupay

7.2 What would you consider as the three most important problems of your barangay? If
respondent is hesitant, ask alternate question: What three areas of concern should the
barangay council devote its attention to? He imo pagkita, ano an tulo nga nangunguna
nga problema han barangay? Ano iton tulo nga baga y nga sadang tagan hin pagtagad
han barangay council para ha kauswagan han barangay?

8.1

8.2

8.3

8.4

8.5

152
1st mentioned 2nd mentioned 3rd mentioned

(0) .poverty/low income
(1) livelihood

(2) peace and order

(3) food

(4) schistosomiasis

(5) health of residents
(6) roads

(7) irrigation

(8) barangay leadership
(9) unity

(1 0) env'tal sanitation ‘

Block 8: Attitudes and outlook

(SHOW LADDER TO RESPONDENT) Here is a drawing of a ladder. It has 10 rungs.
Assuming that the 10th rung represents the best position in life while the 1st rung
represents the worst, on which rung would you place yourself at present? I-ini in Iitrato
hin hagdan nga may ada napulo nga balitang. K un an ika-napulo nga balitang
nakumponer han gimauupayi an pakabuhi ug an primero nga balitang amo an makuri an
kinabuhi, ha pagkayana, diin nga balitang ka nahamumutang?

On which rung would you say you were 5 years ago? Ha imo hunahuna, diin ka
nahamumutang nga balitang ha sakob han nakalaba y nga Iima Icatuig?

On which rung do you think you will be 5 years from now? Pagkatapos hin lima katuig
tikang yana, ha imo panhunahuna, hain ka hini nga balitang mahamumutang

At present, do you think you have opportunities to improve your life? Ha pagkayana nga
imo pagsabut, may ada ka ba oportunidad nga mapauswag an imo pakabuhi?

_0_ none _2_ maybe or not sure _4_ many
_1_ few _3_ don‘t know

If you earn a substantial amount of money, what three things do you want to acquire
within the next 5 years? Kon magkamay-ada ka sadang nga salapi sakob hiton tr'arabot
nga Iima katuig, ano iton tutulo nga bagay nga imo guinhuhuna-hunaan pagpalita?

1st mentioned 2nd mentioned 3rd mentioned

(0) farmland __
(1) carabao/s

9.1

9.2

9.3

9.4

9.5

153

(2) motorcycle

(3) sing-along/karaoke
(4) better house

(5) television

(6) radio

(7) refrigerator

(8) bed

(9) sewing machine
(10) kerosene/electric stove
(11) electric fan

(12) sala set

(13) farm equipment
(14) toilet

Block 9: Community particlpatlon

Are you a member of any barangay organization within Macanip? Miembro Ica ba hin
bisan ano nga organisasyon dinhi hini nga baranga y? Ano nga organisasyon?

_0_ no PROCEED TO QUESTION 9.3
yes PROCEED TO QUESTION 9.2

_1_ Samahang Nayon _5_ BAPA
_2_ Women's Welfare _6_ Barangay Health Workers
_3_ Out of School Youth _7_ Medalla Milagrosa

_4_ Samahang Kabataan _8_ ISA
What is the degree of your involvement in these organizations? Kun usa ka nga
miembro hin organisasyon, tipaunan-O katim-os an imo pag-apr'? PROCEED TO
QUESTION 9.6

_0__ never involved diri ka napartisipar
_1_ some activities nabulig hiton iba nga aktibr'dades
_2_ most activities kaudganan nabulig Ia hiton aktibr'dades

_3_ all activities nga tanan nga aktibidades

Are you interested in joining a barangay organization? Kun diri ka miembro, interesado
ka ba hin pagin miembro hin organisasyon?

_0_ no PROCEED TO QUESTION 9.4
_1_ yes PROCEED TO QUESTION 10.1

Why are you not yet a member? Kay ano nga waray ka naapi?

_0_ too busy or don't have time damo in trabaho ug wara y panahon

_1_ but don't know which to join din' maaram kun diin aapi

_2_ not invited waray nagiimbitar

_3_ but have feelings of inadequacy, ashamed, not fitted naawod
ug may pagturaw nga diri hiya angay maging miembro

It you were made to choose among the following barangay organizations, which would
you join? Kun papipiIi-on Ina pag-api hinin masunod nga mga organr'sasyon, diin mo
gusto magin miembro?

_0_ Samahang Nayon _4_ BAPA
_1_ Women's Welfare _5_ Barangay Health Workers
_2_ Out of School Youth _6_ Medalla Milagrosa

_3_ Samahang Kabataan _7 ISA

9.6

10.1

10.2

10.3

10.4

10.5

154

Which barangay association could effectively be used to control schistosomiasis? Hini
nga mga organisasyon, hain in may kapasidad pag-kontrol han schistosomiasis?

_0_ Samahang Nayon _4_ BAPA
_1_ Women's Welfare _5_ Barangay Health Workers
_2_ Out of School Youth _6_ Medalla Milagrosa

_3_ Samahang Kabataan 7 ISA

Block 10: Attitudes and perceptions toward schistosomiasis

Here is the drawing of the ladder again. Assuming that the 10th rung represents the best
position in terms of how you feel (the condition of your body) vis—a-vis schistosomiasis
and the 1st rung represents the worst, on which rung would you place yourself at
present? Ilni na Iiwat in litrato hin hagdan nga may mga balitang, nga diin an ika napulo
in narepresentar han gimauupayi nga pamalatian han imo Iawas bahin han sakit nga
schistosomiasis, pareho man an primero nga balitang an narepresentar han
gimakokorehi nga pamalatian han imo Iawas bahin han sala't nga schistosomiasis. Dida
hini yana nga panahon, diin mo mahamumutang an imo kalugaringon?

On which rung would you say you were 11 years ago, before the start of treatments by
RITM? Dinhi hini nga hagdan, diin ka nga balitang namumutang onse anyos san-o
magtr'kang pamulong an RIT M?

On which rung do you think you will be 5 years from now, with the continuation of RITM's
treatments? Kun ha sakob pa hin Iima katuig, magpada yon pamulong an RITM, ha imo
panhunahuna diin Ica hini nga balitang mahamumutang?

On which rung do you think you will be 5 years from now, without RITM's treatments?
Kun ha sakob hin Iima katuig diri na mamulong an RI TM, ha imo panhunahuna diin ka
hini nga balitang mahamumutang?

Will you please tell me your feelings or attitudes toward schistosomiasis? Ha imo
kalugaringon nga pagpaino-ino, ala yon pagsumat han imo panghunahuna ug pamatasan
bahin han sakit nga schistosomiasis?

155
AFTER THE INTERVIEW, SAY:

Thank you very much for sharing your precious time with me. Should I need additional
information in the future, are you willing to be interviewed again? Salamat hin madamo han imo
iginhatag nga panahon para hini nga pamakiana. Unta an imo pagtagad ha akon magin amo/a
gihapon kun ha orhi nga panahon manginahanglan pa ako hin dugang nga inponnasyon tikang
ha imo?

no yes

Interviewers Assessment
Which of the following best describes the respondent's attitude toward the interview?

 

interested indifferent
antagonistic hesitant/frightened
inquisitive/suspicious

Which of the following best describes the establishment of rapport?

easily established
established, but with some difficulty
established, but with great difficulty
never established

Which of the following best describes the interview conditions?

very noisy and/or with many distractions
some noise and/or distraction

quiet and/or no distraction

INTERVIEWER'S NOTES

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