In Rutland, the Jamestown Canyon virus has been detected in mosquitos for the first time in state history, the Vermont Department of Health announced Friday. Health officials also detected West Nile virus in St. Albans.
There have been no human or animal cases of mosquito-borne illnesses reported this season, but health officials are urging people to protect themselves by preventing mosquito bites. Jamestown Canyon virus can cause similar illnesses to other mosquito-borne diseases. Mosquitoes are being tested for West Nile virus, Eastern equine encephalitis (EEE) virus — which last year caused two people to get ill and one of them to die — and Jamestown Canyon virus starting from this year.
“Every mosquito group is tested for all three viruses now,” said Natalie Kwit, a public health veterinarian at the Vermont Department of Health. “We added it (Jamestown Canyon virus) because it’s something we knew that’s been circulating in the Northeast, and we had a cost-effective test available that we switched to that included all three viruses.”
The Vermont Agency of Agriculture, Food & Markets and the Vermont Department of Health decided to continue allocating funding to mosquito surveillance this year over tick surveillance to track illnesses like Eastern equine encephalitis after the cases occurred last year. The mosquito surveillance program generally runs from June to mid-October when mosquitos are more active.
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Kwit said most people who become infected with these viruses don’t get sick, but some may develop symptoms a few days, or even weeks, after the mosquito bite.
Symptoms may include fever, body aches, headache, vomiting, diarrhea, rash and joint pains. The viruses can also lead to more serious illnesses like meningitis or encephalitis — an inflammation of the brain that can cause brain damage, stroke and death.
Cases of mosquitoes testing positive to Eastern equine encephalitis have increased significantly in recent years. According to data from the health department, in 2023, 14 groups of mosquitoes across three Vermont towns tested positive for EEE, whereas in 2024, 86 groups of mosquitoes across 16 towns tested positive.
Kwit said only about 5% of people infected with EEE develop a more serious illness. “The thing that worries us the most about Triple E is that about 30 to 40% of people with that severe form of illness die from the disease, so this one tends to be the most severe that we know of,” she said.
There are no vaccines to prevent Eastern equine encephalitis and Jamestown Canyon virus, nor medicines to treat them. The best way to limit the risk of infection is to prevent mosquito bites, according to the health department.
Recommendations from the Vermont Department of Health include wearing long-sleeved shirts and pants, limiting time outside at dawn or dusk when there are more mosquitoes, using insect repellent — the Environmental Protection Agency has a tool to help people identify the right repellent for them — fix holes in screens attached to doors and windows and get rid of standing water that might attract mosquitoes.
