How does West Nile virus cycle in nature?
A. West Nile virus is a disease of wild birds that is maintained in the avian population by mosquitoes that use birds as their preferred blood meal hosts. The Northern House Mosquito, Culex pipiens, is an important bird-feeding species that perpetuates WNV in urban areas as well as farm settings throughout the northeastern United States. WNV is transmitted to humans and horses by mosquitoes that occasionally bite birds but normally use mammals as their preferred blood meal hosts. Culex pipiens may be directly responsible for some human and equine infection, but mammal biters are thought to produce the majority of WNV cases each year. Q. How do horses contract West Nile virus? A. Horses contract WNV when a mosquito that has previously fed on an infected bird bites them. Birds circulate high levels of the pathogen in their blood and serve as the sole source of the virus for mosquitoes. Neither horses nor humans circulate enough virus in their blood when they acquire the disease to pass t
