Eastern Equine Encephalitis (EEE)

What is Eastern Equine Encephalitis?

Eastern equine encephalitis (EEE) is a rare but potentially fatal illness that can be transferred to humans from the bite of an infected mosquito.

How is EEE virus spread?

Mosquitoes become infected with EEE virus when they feed on infected birds. The bite by an infected mosquito can then transmit EEE virus to humans and other animals. It cannot be transmitted directly from person to person.

Who is at risk for EEE?

People of all ages in an area where the virus is circulating can get infected with EEE but the risk is higher for:

  • adults older than 50 and children younger than 15 years of age
  • people who have a weakened immune system
  • people who live in or visit wooded areas
  • people who work outside or participate in outdoor recreational activities

What are the symptoms of EEE?

Some people infected with EEE do not become ill and may not develop symptoms. 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 such as flu-like illness with fever, headache, sore throat, stiff neck, lack of energy, muscle aches and confusion.
  • Severe cases include swelling of the brain (encephalitis) and can lead to coma, convulsions and death. In infants, the encephalitic form has abrupt onset; in older children and adults, encephalitis occurs after a few days of systemic illness. Some of the signs and symptoms include fever, headache, irritability, restlessness, drowsiness, anorexia, vomiting, diarrhea, cyanosis, convulsions, and coma.

If you experience sudden onset of any of the symptoms listed above, seek medical attention immediately. 

How can I protect myself and my family from EEE virus?

The best way to avoid EEE is by not being bitten by mosquitoes.

For more detailed information on protection please refer to our web pages on Mosquito Safety.

Additional resources:

Centers for Disease Control and Prevention - Eastern Equine Encephalitis

Michigan Department of Health and Human Services- Eastern Equine Encephalitis

Key References:

Centers for Disease Control and Prevention. (2018). Eastern Equine Encephalitis.