Many people infected with West Nile virus do not become ill and may not develop symptoms. About 20% of infected people will develop West Nile fever. When symptoms do occur, they may be mild or severe and show up 3 to 15 days after being bitten by an infected mosquito. • Mild symptoms inlcude flu-like illness with fever, headache, body aches, nausea and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. • Severe symptoms include high fever, neck stiffness and swelling of the brain (encephalitis) which can lead to coma, convulsions and death. Less than 1% of infected people will develop severe symptoms.