Influenza is a pathogen of major concern, causing up to 79,000 deaths, 960,000 hospitalizations, and 49 million people sick per year in the US. One of the major route of transmission for influenza is by expelling viruses from coughing/sneezing onto surfaces, followed by transfer of viruses from surfaces to hands, and subsequently to facial mucous membranes.Therefore, routine cleaning and disinfection of surfaces is an important part of the environmental management of influenza A. While the emphasis is generally on spraying hard surfaces and laundering cloth and linens with high temperature machine drying, not all surfaces can be treated in this manner. The quantitative microbial risk assessment (QMRA) approach was used to develop a stochastic risk model for estimating the risk of infection from indirect contact with porous surfaces, with and without surface pre-treatment with an antimicrobial spray product. The data collected from laboratory combined with the risk model show that the risk of influenza A infection can be lowered by four logs when using an antimicrobial spray on a porous surface. Median risk associated with a single touch to a contaminated fabric was estimated to be 1.25 x10-4 for the untreated surface, and 3.6 x10-8 for the treated surface. This single touch scenario was used to develop a generalizable model, allowing to estimate risks by comparing different cases related to more realistic 15 to 30 minutes exposure scenarios associated with multiple surface/face touches. The results of this study demonstrate the effective risk reduction associated with treating porous surfaces that cannot be laundered at high temperatures.
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