The mosquito-borne West Nile virus (WNV) has caused repeated human epidemics in North America and is a zoonotic virus transmitted by Culex mosquitoes whose preferred host is the emblematic American robin (Turdus migratorius). Kilpatrick et al. have shown that the mosquitoes exhibit a shift in feeding behavior when the robins disperse after breeding. In early summer (May and June), about half of the mosquitoes' blood meals come from the robin, despite house sparrows (Passer domesticus) being common and susceptible to infection. In late summer (July to September), the robins disperse and the Culex shift to feeding on humans, again despite the ubiquity of house sparrows. Integrating available data into a model based on a shift in mosquito feeding preference leads to the prediction that the peak transmission of WNV to humans should occur by late July to mid-August and then decline in early October when cold weather hampers mosquito activity. Seasonal shifts in mosquito feeding behavior occur across the United States and appear to intensify epidemics of several avian zoonotic viruses, not only WNV but also Western equine encephalitis virus, St. Louis encephalitis virus, and possibly other vector-borne pathogens. -- CA
PloS Biol. 4, e82 (2006).
