West Nile Virus Encephalitis

West Nile virus encephalitis is a very widely distributed mosquito-borne zoonosis. The West Nile virus (WNV) infects a very wide range of hosts. In 1937, a virus was isolated from a woman in the West Nile district of Uganda and was named after the place as West Nile virus. In 1953, it was isolated from birds, crows and Columbiformes in Nile Delta and was not considered a pathogen. In 1997, its virulent strain caused encephalitis, paralysis and deaths in birds in Israel. Circulating in Israel and Tunisia, it was imported in New York in 1999 causing epidemic. WNV caused largest outbreaks in Israel, Greece, Romania, Russia and the United States. Whole of Africa, parts of Europe, the Middle East, West Asia and Australia happened to be the original regions of WNV activity, and the disease is now endemic from Canada to Venezuela.