A mosquito-borne viral illness caused by the west nile virus, a flavivirus and endemic to regions of Africa, Asia, and Europe. Common clinical features include headache; fever; maculopapular rash; gastrointestinal symptoms; and lymphadenopathy. meningitis; encephalitis; and myelitis may also occur. The disease may occasionally be fatal or leave survivors with residual neurologic deficits. (From Joynt, Clinical Neurology, 1996, Ch26, p13; Lancet 1998 Sep 5;352(9130):767-71)