The goal of my dissertation research is to reconstruct the temporal and spatial associations among El Niño-Southern Oscillation (ENSO), social vulnerability and cholera incidence in Piura, Peru from 1991 to 2001 in order to better understand El Niño's impact on the cholera epidemic in Peru during the 1990s. Piura is important to study because it was one of the first places to report cholera in Peru. It also had one of the highest incidence rates in the country, and historically, the region is known for El Niño. My overarching research questions are: (1) What was the impact of ENSO on cholera incidence in Piura; and (2) How did social vulnerability influence this relationship? My research hypotheses are: (a) There was a temporal association between ENSO, climate and cholera cases in Piura in the 1990s. Furthermore, these associations were stronger after 1992 compared to the onset of the epidemic in 1991; and (b) The spatial variability of the ENSO-climate-cholera associations in Piura in 1997-98 will be explained by the spatial distribution of social vulnerability. Moreover, the level of social vulnerability within districts in Piura will either antagonize or buffer the effects of ENSO and climate on cholera incidence. I address my research questions and hypotheses using a climate affairs approach that is informed by disease ecology and vulnerability theories from the geographic subfields of medical and human-environment geography. Climate affairs is an integrating concept in the earth and social sciences used to understand the interrelationships among climate, environment and society worldwide. Using climate affairs, I developed a conceptual framework that: 1) examines cholera transmission within a broader conception of ENSO; 2) links ENSO-cholera associations to social vulnerability; and 3) considers ENSO-cholera interactions at multiple scales. The key findings of this research suggest that cholera's temporal association with ENSO was transient throughout the 1990s; the strongest association was found during the 1997-98 El Niño. I also found that cholera transmission occurred through the interactions of global and local sea surface temperatures with rainfall. Furthermore, I demonstrated that the spatial distribution of social vulnerability can in part explain the associations between global and local climate and cholera during the 1997-98 El Niño. However, these associations varied by time lag, district and variable. It also appears that districts on the west coast of the subregion of Piura were the most vulnerable. Lastly, important to the understanding of these findings is that interpretation of ENSO and its association with cholera will highly depend on the Niño definition and region chosen for analysis. This research contributes to future climate-informed initiatives that enhance societal capacities, while focusing on population health and the monitoring of populations during future climate events in Piura, Peru and the Latin American region.
Read
