Jamestown Canyon Virus Detected in Penobscot County

Maine CDC shares tips to prevent diseases spread by mosquito bites

AUGUSTA- - The Maine Center for Disease Control and Prevention (Maine CDC) announced today that mosquitoes in the Penobscot County town of Orono tested positive for Jamestown Canyon virus (JCV). This is the first mosquito pool in Maine to test positive this year for any virus transmitted by mosquitoes. There are currently no known human cases of JCV or any other locally-acquired mosquito-borne diseases in Maine this year.

A mosquito pool is a group of one to 50 mosquitoes collected as part of regular surveillance testing, which occurs across Maine during the summer and fall months, beginning in June. The Maine CDC identified the first human case of locally-acquired JCV illness in 2017, and the first JCV-associated death occurred in 2018. In 2023, three mosquito pools tested positive for JCV in Maine. There were no reported human cases of JCV in Maine last year.

Infected mosquitoes can spread three viruses in Maine: JCV, Eastern Equine Encephalitis virus (EEE), and West Nile virus (WNV). Although rare, these diseases can have severe and even fatal consequences. The best protection is to take precautions against mosquito bites.

Many people infected with these viruses show no symptoms. Others experience mild flu-like symptoms such as fever, headache, and weakness. Some people may experience severe symptoms, including:

  • Vomiting
  • Neck stiffness
  • Loss of coordination
  • Speech difficulties
  • Confusion
  • Seizures
  • Encephalitis (brain swelling)
  • Meningitis (inflammation of tissues around the brain and spinal cord)

If untreated, some infections can lead to death. If you experience any of these symptoms, call a health care provider right away.

The Maine CDC urges Maine people and visitors to take the following protective measures:

  • 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.
  • Regularly drain any artificial sources of standing water where mosquitoes lay eggs, such as bird baths, dog bowls, buckets, and children’s toys.
  • Take steps to prevent mosquito bites when traveling.

To help prevent mosquito-borne diseases in pets, the Maine CDC recommends speaking to your veterinarian. Maine CDC also encourages horse owners to vaccinate against EEE and WNV.

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