Eastern Equine Encephalitis Identified in Maine Mosquitoes

AUGUSTA – The Maine Center for Disease Control and Prevention (Maine CDC) announced today that mosquitoes from the York County town of Lebanon tested positive for Eastern equine encephalitis virus (EEE).

These are the first mosquitoes in Maine to test positive for EEE since 2019, when a horse also tested positive. The last human case of EEE in Maine was in 2015. No known human cases of any locally acquired mosquito-borne illnesses have occurred in Maine this year.

Besides EEE, mosquitoes in Maine can also spread Jamestown Canyon virus (JCV) and West Nile virus (WNV). These viruses spread through the bite of an infected mosquito. They cannot spread from human to human or from human to animal.

While some people may not exhibit symptoms from EEE, others may experience fever and flu-like illness. Severe symptoms can occur, including encephalitis (brain swelling), and meningitis. In some cases, EEE is fatal. If you experience any symptoms, call a health care provider right away.

Maine people and visitors can take these simple steps to protect themselves from EEE, JCV, and WNV:

  • Wear long sleeves and long pants.
  • Use an EPA-approved repellent on skin and clothes.
  • Take extra precautions at dusk and dawn when mosquitoes are most active.
  • Use screens on windows and doors.
  • Drain artificial sources of standing water around the home where mosquitoes can lay eggs, such as bird baths, wheelbarrows, plant pots, and pet water dishes.
  • Take steps to prevent mosquito bites when traveling.

Horses are also sensitive to mosquito-borne diseases and can be vaccinated for EEE and WNV. Symptoms of these diseases in horses include:

  • fever
  • weakness
  • lack of coordination

If you notice any of these symptoms in your horse, talk to your veterinarian right away.

Maine CDC tests mosquito pools – groups of one to 50 mosquitoes collected as part of regular testing – for EEE and WNV throughout the summer months, starting in July. Weekly mosquito surveillance reports for this season are available at www.maine.gov/dhhs/vectorborne.

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