West Nile virus (WNV) is most commonly transmitted to humans by mosquitoes. You can reduce your risk of being infected with WNV by using insect repellent and wearing protective clothing to prevent mosquito bites. There are no medications to treat or vaccines to prevent WNV infection. Fortunately, most people infected with WNV will have no symptoms. West Nile virus infection can cause serious disease. About 1 in 5 people who are infected will develop a fever with other symptoms. Less than 1% of infected people develop a serious, sometimes fatal, neurologic illness.
WNV is established as a seasonal epidemic in North America that flares up in the summer and continues into the fall.
West Nile Virus is not spread by person-to-person contact and being bitten by a mosquito does not mean you will get the virus. Even in areas where mosquitoes have been found to carry the virus, less than 1% of them are infected. If a mosquito is infected, less than 1% of people who are bitten by that mosquito will become severely ill.