Laboratory Diagnosis of West Nile Virus Encephalitis Virus Infection

West Nile Virus (WNV) is a member of the flavivirus genus and belongs to the Japanese encephalitis antigenic complex, which includes other neurotropic viruses such as Murray Valley encephalitis virus (MVEV), St. Louis encephalitis virus (SLEV) and Usutu virus (USUV). WNV is an arbovirus transmitted in a zoonotic cycle between birds and ornithophilic mosquitoes, primarily of the Culex species. Horses and humans can also be incidentally infected. The majority of WNV infections are asymptomatic or cause mild illness. However, WNV can infect the central nervous system and cause a neurological disease that is usually severe.