WNV is an enveloped, neurotropic, single-stranded sense RNA flavivirus that is naturally maintained in a zoonotic cycle between avian hosts and mosquito vectors. The virus was first isolated from a Ugandan woman in 1937 and subsequently emerged in Europe and, in 1999, in New York, with eventual spread throughout North America. WNV causes a spectrum of disease ranging from acute fever to lethal encephalitis. Susceptibility to WNV is increased in the elderly and in immunocompromised individuals (summary by Diamond and Klein (2006) and Glass et al. (2005)). [from
OMIM]