Crow deaths as a sentinel surveillance system for West Nile virus in the Northeastern United States, 1999

In addition to human encephalitis and meningitis cases, the West Nile (WN) virus outbreak in the summer and fall of 1999 in New York State resulted in bird deaths in New York, New Jersey, and Connecticut. From August to Decem ber 1999, 295 dead birds were laboratory-confirmed with INN virus infection ; 262 (89%) were American Crows (Corvus brachyrhynchos). The New York State Department of Health received reports of 17,339 dead birds, including 5,69 7 (33%) crows; in Connecticut 1,040 dead crows were reported. Bird deaths w ere critical in identifying WN virus as the cause of the human outbreak and defining its geographic and temporal limits. If established before a WN vi rus outbreak, a surveillance system based on bird deaths may provide a sens itive method of detecting WN virus.