Eastern equine encephalitis virus (EEEV) -member of the genus Alphavirus, family Togaviridae– is transmitted to humans by the bite of an infected mosquito. Eastern equine encephalitis (EEE) is a rare illness in humans. Most persons infected with EEEV have no apparent illness. Severe cases of EEE (involving encephalitis) begin with the sudden onset of headache, high fever, chills, and vomiting. The illness may then progress into disorientation, seizures, or coma.