The Effect of Temperature on West Nile Virus Transmission Dynamics

Abstract

West Nile virus (WNV) is a vector-borne disease that first appeared in New York in 1999, then in Southern Ontario, Canada in 2002. Since its arrival, WNV has rapidly spread across the North American continent to establish itself as a seasonal endemic infection. Among other environmental variables, temperature is the primary determinant of WNV transmission dynamics. In this dissertation, the relationship between temperature and WNV transmission dynamics is investigated and a single-season predictive model that explicitly accounts for temperature in various biological and epidemiological processes is proposed. First, we develop a mosquito abundance model where temperature is the driving force behind mosquito development, survival, and diapause. Then, the model is extended to include the WNV transmission cycle between mosquitoes and birds. Under simplifying assumptions, we derive an expression for the basic reproduction number and analyze its dependence on temperature. The transmission model was applied to the Peel Region in Southern Ontario for validation. Numerical results demonstrate the capacity of the model to capture the within-season trends of mosquito- and WNV- surveillance data. The proposed model can potentially be used as a real-time predictive tool to inform public health policy.