It was first identified in the United States in the late summer of 1999. People become infected from the bite of an infected mosquito. Mosquitoes become infected by biting birds, which are infected with the virus. Not all humans infected with the disease will become ill. Most infections are mild and symptoms include fever, headache, body aches, skin rashes and swollen lymph glands.
Most people recover from the disease.
When more severe symptoms occur, they can range from fever, rash and headache to meningitis, encephalitis, coma and death. People who live or work in areas where active cases have been identified are at risk of getting West Nile virus if bitten by an infected mosquito. However, people over the age of 50 and those with weak immune systems are at greater risk for more serious illness. There is no specific treatment for West Nile virus, nor is there a vaccine. Most people recover completely within 2 weeks.