Modeling biotic and environmental drivers of seasonal West Nile virus transmission

West Nile virus (WNV) is the most prevalent arbovirus in the US and seriously threatens the health of livestock, wildlife (especially birds) and humans. WNV transmission shows clear annual cycles, with high levels of human and animal cases during the summer, and few or no cases during the late fall, winter, and early spring. Furthermore, WNV transmission is higher in urban areas relative to rural areas. Yet, we do not fully understand what is driving seasonal and spatial differences in WNV transmission, or how cycles of WNV transmission are able to reinitiate each year. The investigators work from the central hypothesis that mosquitoes and birds are affected by differences in rural and urban landscapes that lead to predictable, seasonal changes in WNV transmission. The overall objective of this proposal is to develop predictive models that incorporate critical drivers of WNV transmission in rural and urban areas, including seasonal changes in mosquito and avian abundance and community composition. The research team has complementary expertise in mosquito overwintering, mathematical modeling, and avian disease ecology. This proposal combines sophisticated mathematical models with high-resolution, field data from mosquitoes and birds in rural and urban sites in central and northwestern Ohio. The first goal of the proposal is to uncover how WNV transmission reinitiates each spring. Mosquito and avian community composition, WNV infection, mosquito host-use, WNV phylogenetics and measures of urbanization will be incorporated into predictive models and used to test the hypotheses that WNV-infected urban mosquitoes terminate their overwintering dormancy in early spring, while uninfected rural mosquitoes acquire WNV from migratory birds. The second goal is to characterize factors that drive WNV transmission during the peak of the epidemic. Abiotic factors and data from birds and mosquitoes will be incorporated into models to determine why WNV transmission starts earlier, persists longer and is higher in cities relative to rural areas. The third goal is to determine how WNV persists during fall and winter. Continuous collections of rural and urban mosquitoes and birds, WNV phylogenetics and environmental data will be modeled to test the hypotheses that urbanization postpones mosquito overwintering dormancy, increases WNV in birds, and allows more urban mosquitoes to overwinter infected with WNV. Finally, the models will be re-coded to be adaptable to multiple locations using freely available, open-source weather, bird, and mosquito data. Thus, at the conclusion of this work the PIs will have developed, parameterized, and validated the first multispecies, multiannual, and adaptable models to predict WNV transmission across time and space.