West Nile virus is transmitted by mosquitoes. If you become infected with West Nile virus, you may not experience any signs or symptoms or you may only experience minor ones such as a skin rash and headache. However, some people who become infected with West Nile virus develop a life-threatening illness that includes inflammation of the brain.

West Nile virus is common in areas such as Africa, West Asia and the Middle East. It first appeared in the United States in the summer of 1999 and since then has been found in all 48 contiguous states.

Exposure to mosquitoes where West Nile virus exists increases your risk of getting West Nile virus. Protecting yourself from such exposure, such as by using mosquito repellent and wearing clothing that covers your skin, can reduce your risk.