Department of Health representatives from Washington, D.C., New York, and New Jersey have detected their first avian cases of West Nile virus (WNV) in 2002. Washington, D.C., reported its first WNV-infected bird on May 13, which was found May 1 a block from the national zoo. May 16 brought the health department laboratory announcement of a WNV-positive bird retrieved from Albany County, NY. Finally, New Jersey officials announced May 20 that five crows in Monmouth and Morris counties tested postive for WNV.

West Nile virus is spread to horses, birds, and humans through the bite of infected mosquitoes. It has spread in all directions from its original epicenter in the state of New York in 1999, and is now considered endemic throughout much of the East coast. The virus had never before appeared in the Western Hemisphere before 1999. The virus killed 36% of its diagnosed equine victims in 1999, 38% in 2000, and 33% in 2001. An equine vaccine was developed and released under a conditional license in August of 2001 (https://thehorse.com/ViewArticle.aspx?ID=1109). Equine WNV cases are treated with supportive care.

Other states affected by WNV this year include Illinois, Louisiana, Pennsylvania, Virginia, and Florida. Currently, Florida is the only state with equine WNV cases this year (five as of May 20). The virus was detected earlier in various states in 2002 compared to past years, and this trend has been attributed to factors such as enhanced surveillance and a mild winter that brought out the mosquitoes earlier than usual.

In 2001, Washington, D.C., had its first report of a WNV-positive bird in mid-July. The number of cases increased from there and peaked in mid- to late-September. New York had its first 2001 avian findings in mid-May, with the numbers of positive cases picking up in August and peaking at the beginning of September. New Jersey had announced its first 2001 WNV-positive birds in early May, increased numbers beginning in mid-July, and a peak of cases in mid-August