How do people get infected with West Nile virus?
West Nile virus occurs mostly in birds. Mosquitoes pick the virus up when they feed on infected birds and transmit it when they feed on uninfected birds. When the number of infected birds and mosquitoes reaches a certain level then transmission to other animals, including humans and horses, starts to occur.
The route of human infection with West Nile virus is through the bite of an infected mosquito. Mosquitoes become infected when they bite an infected bird and the virus eventually finds its way into the mosquito’s salivary glands. If the infected mosquito then bites a human, the virus may be injected into that person’s bloodstream where it can multiply and possibly cause illness. Animals can also be infected in this manner.
