West Nile viral encephalitis

West Nile virus (WNV) has emerged in recent years in temperate regions of E urope and North America, presenting a threat to both public and animal heal th. The most serious manifestation of infection is fatal encephalitis in hu mans and horses, as well as mortality in certain domestic and wild birds. a recent development in the epizootiology of this mosquito-borne flavivirus was the occurrence of a severe outbreak in New York City and surrounding ar eas. During this outbreak, mortality was observed in humans, horses, a cat and numerous species of wild birds, particularly members of the family Corv idae (crows). The author reviews basic information and summarises recent de velopments in the epidemiology and epizootiology of WNV.