The virus was isolated at NVSL laboratories, and forwarded to the CDC for identification and characterization. Surveillance is ongoing, and wild bird death reports are being encouraged. An outbreak of arboviral encephalitis first occurred in New York City in late August and has since been identified in other New York, Connecticut, and New Jersey counties. Prior to and during this outbreak there have been mortalities in crows around the New York City area. The virus was isolated at NVSL laboratories, and forwarded to the CDC for identification and characterization.
Surveillance is ongoing, and wild bird death reports are being encouraged.
Recent outbreaks have included a large one in Romania during 1996-1997, and one in Italy in 1998 prior to which there had never been any clinically or serologically confirmed cases in the country. Perhaps the limits of whether or not the virus has been isolated from a particular bird species is dependent on whether that species has been tested. Chickens have been used as sentinels during surveillance efforts in countries with endemic infection. Typically the West Nile virus does not cause a high mortality in crows. That so many crows have been affected in this outbreak could be due to exposure of a naive bird population or a new, more virulent stain.