Mosquito-Borne Virus Identified in Maine Mosquitoes

Maine CDC warns of risk of disease from mosquitoes, including during dry weather

AUGUSTA-- The Maine Department of Health and Human Services' Maine Center for Disease Control and Prevention (Maine CDC) announced today that mosquitoes in the Cumberland County city of Portland tested positive for West Nile virus (WNV).

These are the first mosquito pools to test positive for any mosquito-borne virus in Maine this year. A mosquito pool is a group of up to 50 mosquitoes collected through routine surveillance testing, which occurs in targeted locations across the state during the summer and fall months. Four wild birds also tested positive for WNV this year. The birds were from Kennebec, Sagadahoc, and York Counties.

"Even though it has been dry across much of Maine this summer, the mosquitoes that spread WNV can thrive in this weather," said Maine CDC Director, Dr. Puthiery Va."Some mosquitoes love to lay eggs in standing water around our homes, and they only need the equivalent of a bottle cap of standing water to do so. To lower your risk of getting sick from a mosquito bite, dump out artificial sources of standing water such as bird baths, pet dishes, empty plant pots, and other vessels and take personal protective measures to keep yourself and your loved ones safe."

Besides WNV, mosquitoes in Maine can also spread Eastern Equine Encephalitis virus (EEE) and Jamestown Canyon virus (JCV). The Maine CDC tests mosquitoes and wild birds for these viruses during mosquito season which typically runs from the summer into the fall months. This provides an early warning before viruses spread to people or domestic animals.

Many infected people have no symptoms. Others experience fever and flu-like illness. Severe symptoms can occur, including encephalitis (brain swelling), and meningitis (inflammation of the spinal cord). If you experience any of these symptoms, call a health care provider, especially if a COVID-19 test is negative.

The best protection against all mosquito-borne diseases is to prevent bites. The Maine CDC recommends taking these precautions when going outside:

  • Take extra precautions at dawn and dusk, when mosquitoes are most active.
  • Wear loose fitting clothing that covers the arms and legs.
  • Use an EPA-approved repellent on skin and clothes. This includes DEET, picaridin, IR3535, and oil of lemon eucalyptus. Use permethrin on clothing.
  • Drain artificial sources of standing water around the yard. This is where mosquitoes can lay eggs.
  • Use screens on windows and doors.

To help prevent mosquito-borne diseases in pets, talk to your veterinarian. Horse owners can protect horses with vaccines against WNV and EEE.

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