Potential for New York mosquitoes to transmit West Nile Virus

We evaluated the potential for several North American mosquito species to t ransmit the newly introduced West Nile (WN) virus. Mosquitoes collected in the New York City Metropolitan Area during the recent (1999) WN outbreak we re allowed to feed on chickens infected with WN virus isolated from a crow that had died during this outbreak. These mosquitoes were tested approximat ely 2 weeks later to determine infection, dissemination, and transmission r ates. Culex pipiens mosquitoes were highly susceptible to infection, and ne arly all individuals with a disseminated infection did transmit WN virus by bite. In contrast, Aedes vexans were only moderately susceptible to oral i nfection; however, those individuals inoculated with WN virus did transmit virus by bite.