Science Source

Drought and immunity determine the intensity of West Nile virus epidemics and climate change impacts

Uses analyses at national and state scales to examine a suite of climatic and intrinsic drivers of continental-scale West Nile virus epidemics, including an empirically derived mechanistic relationship between temperature and transmission potential that accounts for spatial variability in vectors
Finds that drought was the primary climatic driver of increased West Nile virus epidemics, rather than within-season or winter temperatures, or precipitation independently
Finds that local-scale data from one region suggested drought increased epidemics via changes in mosquito infection prevalence rather than mosquito abundance
Finds that human acquired immunity following regional epidemics limited subsequent transmission in many states.
Shows that over the next 30 years, increased drought severity from climate change could triple West Nile virus cases, but only in regions with low human immunity
These results illustrate how changes in drought severity can alter the transmission dynamics of vector-borne diseases