Scores of birds, mostly crows, have also died, and several horses in New York tested positive for the virus. An indeterminable number of infections in humans, birds, horses, and other vertebrates are believed to have occurred. The virus was also diagnosed in a cat in New Jersey. In the wake of the West Nile virus outbreak, countries including those in the European Union have temporarily banned or restricted US imports of horses and poultry. Chicken inoculation studies conducted by the USDA National Veterinary Services Laboratories have been completed, and as of press time, the data are being compiled.
Initial reports show the chickens developed high, short-lived viremias and shed the virus in feces.
Contact birds in the same cages as the inoculated birds did not appear to be affected. Results from turkey inoculation studies by the USDA Agricultural Research Service are not yet available. Although mosquito activity in the Northeast has been curtailed by cold weather, there are concerns that infected migratory birds will introduce the West Nile virus to new regions within the United States. When the human outbreak was initially thought to be St Louis encephalitis, a flavivirus similar to the West Nile virus, routine testing of sentinel birds in New York state by the Centers for Disease Control and Prevention revealed subclinical infections in such species as mallards, pigeons, and Canada geese. The virus was later found outside the three initially involved states when it was diagnosed in a crow in Baltimore.