Transmission of West Nile and five other temperate mosquito-borne viruses peaks at temperatures between 23-26ºC

The temperature-dependence of many important mosquito-borne diseases has
never been quantified. These relationships are critical for understanding
current distributions and predicting future shifts from climate change. We
used trait-based models to characterize temperature-dependent transmission
of 10 vector–pathogen pairs of mosquitoes (Culex pipiens, Cx.
quinquefascsiatus, Cx. tarsalis, and others) and viruses (West Nile,
Eastern and Western Equine Encephalitis, St. Louis Encephalitis, Sindbis,
and Rift Valley Fever viruses), most with substantial transmission in
temperate regions. Transmission is optimized at intermediate temperatures
(23–26ºC) and often has wider thermal breadths (due to cooler lower
thermal limits) compared to pathogens with predominately tropical
distributions (in previous studies). The incidence of human West Nile
virus cases across US counties responded unimodally to average summer
temperature and peaked at 24ºC, matching model-predicted optima (24–25ºC).
Climate warming will likely shift transmission of these diseases,
increasing it in cooler locations while decreasing it in warmer locations.