Officials Detect First Mosquito-Borne Virus of 2026 Season

Officials Detect First Mosquito-Borne Virus of 2026 Season
Jamestown Canyon virus was found in mosquitoes collected in Chittenden County 

WATERBURY, VT — Jamestown Canyon virus (JCV) has been detected in mosquitoes collected in Charlotte. This is the first detection of a mosquito-borne virus in Vermont this year. No cases of mosquito-borne illnesses have been reported in people or animals yet this season.

Health officials are encouraging Vermonters to protect themselves from mosquito bites and the potentially dangerous diseases they can spread, including Jamestown Canyon virus, West Nile virus and Eastern equine encephalitis (EEE) virus. 

“It’s not too early to take precautions to protect yourself from mosquito bites,” said Natalie Kwit, state public health veterinarian with the Health Department. “This is a relatively early detection of a mosquito-borne virus in Vermont compared to recent years, but is not abnormal for this virus. We can expect to see more virus detections as the season progresses and the risk of exposure to infected mosquitoes increases.”

The state began testing mosquitoes for JCV last year, identifying it in mosquitoes in Vermont for the first time. The first human case in Vermont was also reported in 2025.

JCV can cause symptoms similar to those caused by other mosquito-borne viruses. Most people who are infected with mosquito-borne viruses do not feel sick, but symptoms can include fever, headache, body aches, joint pains, vomiting, diarrhea, or a rash. Serious illnesses can also occur, such as inflammation of the brain, called encephalitis. Anyone who develops these symptoms should contact their health care provider.

The best way to protect yourself and your family is to prevent mosquito bites: 

• Wear long-sleeved shirts and pants outdoors.
• Limit your time outside at dawn and dusk when mosquitoes are more likely to bite.
• Use insect repellent labeled as effective against mosquitoes. The EPA has a tool to help find the right repellent for you. These products can also protect you from tick bites.
• Get rid of standing water, including flowerpots, buckets, barrels, wading pools and other toys and containers.
• Cover strollers and outdoor playpens with mosquito netting.
• Fix holes in screens and make sure they are tightly attached to doors and windows. 
   

Since 2002, there have been 17 confirmed human cases of West Nile in Vermont. EEE, or “Triple E” – which is more deadly – caused illnesses in two people in Vermont in 2024, one of whom died. During 2023–2024, significantly higher numbers of mosquitoes tested positive for EEE virus in more areas of the state than in any previous years.

Horse owners should consult their veterinarians and make sure their animals are up to date on vaccinations for West Nile, 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. 

As part of the state’s annual surveillance efforts, the Agency of Agriculture, Food and Markets collects thousands of mosquitoes throughout Vermont each week, which are then tested at the State Public Health Laboratory. 

Learn more about mosquitoes, the diseases they spread, and how to prevent bites – Visit HealthVermont.gov/Mosquito.

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