What is West Nile virus?

West Nile virus is a virus commonly found in Africa, West Asia and the Middle East. It is closely related to the virus that causes St. Louis encephalitis. West Nile virus can infect humans, birds, mosquitoes, horses and some other mammals.

• WestNile.ca.gov
• Centers for Disease Control West Nile Virus
• California Surveillance and Facts About West Nile Virus.