|West Nile virus is an arbovirus (short for
arthropod-borne virus) that causes encephalitis (inflammation of the
brain). Arboviruses are transmitted by blood-feeding insects such as
mosquitoes. Most infections with West Nile virus have been identified
in wild birds, horses and humans, but the virus can also infect various
other wild and domestic animals.
West Nile virus was
first identified in the
West Nile district of Uganda in 1937, and has since been found in other
parts of Africa, Eastern Europe, West Asia, the Middle East, and the
United States. The strain of virus found in the United States most
closely resembles that found in the Mediterranean and Middle East. The
virus has been reported in nearly all states.