Human West Nile virus surveillance--Connecticut, New Jersey, and New York, 2000.

West Nile virus (WNV), a mosquitoborne arbovirus identified in New York in 1999, has become enzootic in the northeastern United States, affecting humans, birds, horses, and other mammals. Although no human WNV infection was identified in Connecticut or New Jersey in 1999, 62 persons with WNV illness, including seven deaths, were detected in New York City (NYC) and nearby New York counties. In 2000, these jurisdictions implemented active surveillance (AS) and enhanced passive surveillance (EPS) to detect human illness; 21 persons were identified with acute WNV infection (14 in New York, six in New Jersey, and one in Connecticut), including two deaths (one each in New York and New Jersey). This report summarizes the human WNV surveillance systems in Connecticut, New Jersey, New York, and NYC and recommends EPS for hospitalized patients with encephalitis of unknown etiology for the continental United States.