Isolation of West Nile virus from mosquitoes, crows, and a Cooper's hawk in Connecticut

West Nile (WN) virus, a mosquito-transmitted virus native to Africa. Asia. and Europe, was isolated from two species of mosquitoes, Culex pipiens and Aedes vexans, and from brain tissues of 28 American crows, Corvus brachyrhy nchos, and one Cooper's hawk, Accipiter cooperii, in Connecticut. A portion of the genome of virus isolates from four different hosts was sequenced an d analyzed by comparative phylogenetic analysis. Our isolates from Connecti cut were similar to one another and most closely related to two WN isolates from Romania (2.8 and 3.6 percent difference). If established in North Ame rica, WN virus will likely have severe effects on human health and on the h ealth of populations of birds.