West Nile Virus Underlying Cause
West Nile virus is caused by a flavivirus that is transmitted from animals to humans through the bite of a mosquito.
After infection, the virus may or may not cause illness. Rarely, the virus causes inflammation of the brain, called encephalitis, which can cause severe symptoms.
Continue to West Nile Virus Transmission
- Calisher CH. Medically important arboviruses of the United States and Canada. Clin Microbiol Rev. 1994 Jan;7(1):89-116. 
- Mackenzie JS, Gubler DJ, Petersen LR. Emerging flaviviruses: the spread and resurgence of Japanese encephalitis, West Nile and dengue viruses. Nat Med. 2004 Dec;10(12 Suppl):S98-109.