WATERBURY – Even as the weather cools, health officials are urging people to take steps to prevent mosquito bites after Eastern equine encephalitis (EEE) virus, a serious and potentially deadly mosquito-transmitted virus, has been detected for the first time this year in Franklin, Addison and Orleans counties.
Mosquitoes from Swanton and Vergennes have tested positive for the virus, and a horse in Brownington is also suspected to have had the virus.
There have not been any cases of EEE reported in people in Vermont this year, but the risk for infection increases into late summer and early fall. The virus caused serious illness in two people in Vermont last year, one of whom died.
“Detection of dangerous viruses carried by mosquitoes in Vermont underscores that it’s important for all of us to prevent bites and protect our health, especially in communities where these mosquitoes have been found,” said Interim Health Commissioner Julie Arel.
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Most people who are infected with mosquito-borne viruses including EEE may not feel sick, but infection can lead to serious illness including inflammation of the brain, called encephalitis. Symptoms can include fever, headache, body aches, joint pains, vomiting, diarrhea or a rash. Anyone who feels symptoms like these should contact their health care provider.
The best protection is to prevent mosquito bites include limit time outside at dawn and dusk when mosquitoes are more likely to bite, wear long-sleeved shirts and pants outdoors, use insect repellent labeled as effective against mosquitoes, get rid of standing water and cover strollers and outdoor playpens with mosquito netting and fix holes in screens and make sure they are tightly attached to doors and windows.
As part of the state’s annual surveillance efforts, the Vermont Agency of Agriculture, Food and Markets collects mosquitoes throughout Vermont, which are tested by the Health Department at the State Public Health Laboratory.
Mosquitoes are tested for three viruses that are spread through the bite of an infected mosquito: West Nile virus, EEE virus, and new this year, Jamestown Canyon virus. Vermont confirmed its first human case of Jamestown Canyon virus on September 9. Mosquitoes first tested positive for West Nile and Jamestown Canyon viruses in July.
Horse owners should consult their veterinarians and make sure their animals are up to date on vaccinations for West Nile virus, EEE and other diseases spread by infected insects or ticks. Horses cannot spread these viruses to humans or other horses, but the infections can cause neurologic disease and death in unvaccinated animals. Two horses were confirmed to have died from EEE in 2024, in addition to the suspected case this year in Brownington.
Learn more about mosquitoes, the diseases they spread, and how to prevent bites visit HealthVermont.gov/Mosquito.
