Serologic evidence for West Nile virus infection in birds in the New York City vicinity during an outbreak in 1999

As part of an investigation of an encephalitis outbreak in New York City, w e sampled 430 birds, representing 18 species in four orders, during Septemb er 13-23, 1999, in Queens and surrounding counties. Overall, 33% were posit ive for West Nile (WN) virus-neutralizing antibodies, and 0.5% were positiv e for St. Louis encephalitis virus-neutralizing antibodies. By county, Quee ns had the most seropositive birds for WN virus (50%); species with the gre atest seropositivity for WN virus (sample sizes were at least six) were Dom estic Goose, Domestic Chicken, House Sparrow, Canada Goose, and Rock Dove. One sampled bird, a captive adult Domestic Goose, showed signs of illness; WN virus infection was confirmed. Our results support the concept that chic kens and House Sparrows are good arbovirus sentinels. This study also impli cates the House Sparrow as an important vertebrate reservoir host.