WHITINGHAM-Mosquitoes in Whitingham have tested positive for mosquito-borne Jamestown Canyon virus (JCV). Vermont began testing for the virus this summer. In light of the presence of the virus, officials urge residents throughout the valley to take precautions to prevent mosquito bites.
JCV can be contracted by people when they are bitten by an infected mosquito. To date, no human cases have been reported in Vermont.
However, Vermont Public Health Veterinarian Natalie Kwit has told The Deerfield Valley News this week that the presence of infected mosquitoes in Whitingham could be the "tip of the iceberg" and said people throughout the Deerfield Valley should take precautions to prevent contracting the virus.
"It's an important reminder to take precautions to reduce your risk," said Kwit. "These mosquitoes we're collecting around the state are just a sample of all that are out there [which] indicates there could be more infected mosquitoes around."
Kwit said state officials generally urge caution within a 10-mile radius of positive detection of a virus in mosquitoes.
Though Kwit said scientists are still learning about JCV and how it spreads within Vermont, it's the case with other mosquito-borne viruses that mosquitoes contract viruses from birds, which can carry infections and have wider flight areas than mosquitoes may. Deer, she said, may also be an intermediate species for JCV.
Late summer and early fall, said Kwit, are when mosquito-borne illnesses are typically the most abundant.
"The season has gone on long enough where there's more birds and intermediate hosts infected, and therefore there's more infected mosquitoes carrying the virus," she said.
The state tests mosquitoes from May to October each year. Samples are collected weekly by the Agency of Agriculture. Data is summarized and reported weekly by the Department of Health.
West Nile virus (WNV) and eastern equine encephalitis virus (EEE) have been tested for in recent years and continue to be surveilled. JCV, which is common in the Midwest, has emerged throughout New England in recent years. As a result of human cases in neighboring states, Vermont added JCV to its surveillance for 2025.
Kwit said that for many who contract mosquito-borne viruses, including JCV, the illness is asymptomatic, meaning the person never knows they have the virus.
For those who do have symptoms with JCV, their onset can happen weeks after a bite occurs. Symptoms typically include headache and fatigue. According to the CDC, some people also experience respiratory symptoms such as cough, sore throat, and runny nose. In rare cases, the virus can cause encephalitis and meningitis.
In addition to JCV, in 2025, WNV has been detected in mosquito pools in northern Vermont, in Rockingham, and in Bennington. As with JCV, no human cases have been reported in the state this year.
Encouragingly, said Kwit, the state has not yet detected EEE in 2025. EEE can also cause encephalitis and meningitis. Last year, there were two human cases of EEE in Vermont. One person died from the disease.
Kwit encourages all Vermonters to take precautions to prevent mosquito bites, which is the most effective way to prevent contraction of mosquito-borne viruses, for which there are no vaccines or cures for humans. (Horse vaccines exist for EEE and WNV.)
Those precautions include:
• avoiding being outdoors during dawn and dusk when mosquitoes are most active
• wearing long sleeves and pants outdoors when possible
• wearing bug repellant sprays when outdoors
In addition, Kwit said that removing any standing water from yards can help thwart mosquito populations from growing.
To learn more about mosquito-borne illnesses in Vermont, visit healthvermont.gov/disease-control/mosquito-borne-diseases/mosquitos_vermont.
A version of this story appeared in The Deerfield Valley News, The Commons' sister newspaper.
This News item by Lauren Harkawik originally appeared in The Deerfield Valley News and was republished in The Commons with permission.