Maine CDC Press Release

September 17, 2019

Eastern Equine Encephalitis confirmed in mosquitoes in York County

Mainers urged to take precautions against illnesses transmitted by mosquito bites

AUGUSTA – The Maine Center for Disease Control and Prevention (CDC) announced today that mosquitoes in York County tested positive for Eastern Equine Encephalitis (EEE).

Maine's Health and Environmental Testing Laboratory (HETL) confirmed the presence of EEE in a single mosquito pool (a collection that contains 1-50 mosquitoes) collected on September 6, 2019, in the town of Lebanon.

"This test confirms that mosquitoes carrying this potentially fatal virus are still active in Maine," said Maine CDC Director Nirav D. Shah. "We urge residents and visitors to continue to take steps to protect themselves from mosquito bites."

EEE is a virus that is transmitted through the bite of an infected mosquito. It cannot be transmitted from human to human or animal to human.
Last month, Maine CDC announced that a horse in York County was euthanized after contracting EEE.

Maine CDC advises minimizing outdoor activity from dusk to dawn, when mosquitoes are most active. If outdoor activity is unavoidable, take precautions to prevent mosquito bites, including:

  • Wear protective clothing: long-sleeved shirts, long pants, and long socks
  • Use an EPA-approved repellent
  • For use on skin: DEET, Picaridin, IR3535, Oil of Lemon Eucalyptus
  • For use on gear and clothing: Permethrin
  • Take steps to control mosquitoes around your property by emptying artificial sources of standing water, fixing holes in screens, and working with a pesticide control applicator.

The risk of mosquito-transmitted diseases such as EEE and West Nile virus (WNV) usually increases through the late summer and early fall. Mosquitoes are active until the second hard frost.

There have been no confirmed cases of EEE or WNV in humans in Maine this year. The last case of EEE involving a human in Maine was in 2015.

Human infection with EEE virus can cause serious illness affecting the brain. Some persons infected with EEE have no obvious symptoms. In those who do develop illness, initial symptoms may include fever, headache, weakness, and body and muscle pain. Symptoms typically begin four to 10 days after a bite from an infected mosquito, and last one to two weeks. In more serious cases, the disease may progress to swelling of the brain, neck stiffness, confusion, seizures, and coma. Approximately one in every three individuals who are infected with EEE die and many survivors experience serious and lasting health problems. Individuals with symptoms suggestive of EEE infection should contact their physician immediately.

No human vaccine against EEE or WNV infection is available. There is no specific antiviral treatment for EEE or WNV infections. Preventing mosquito bites is the best protection.

Maine has many resources on mosquito-borne diseases:

For more information about EEE and WNV prevention, visit these CDC websites: or