Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Eastern equine encephalitis (EEE) is a rare but severe viral infection of the brain caused by the Eastern equine encephalitis virus (EEEV). It is transmitted to humans and horses through the bite of an infected mosquito.
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EEE can cause inflammation of the brain leading to severe neurological damage or death.
The primary vector for EEEV transmission is the Culiseta melanura mosquito, which primarily feeds on birds.
Symptoms of EEE include high fever, headache, irritability, restlessness, drowsiness, anorexia, vomiting, diarrhea, and convulsions.
There is no specific antiviral treatment for EEE; supportive care in a hospital setting is typically required.
The case fatality rate for EEE in humans ranges from 30% to 70%, making it one of the most deadly mosquito-borne diseases in North America.