Jamestown Canyon Virus | Vermont Department of Health
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Jamestown Canyon Virus
Mosquito-borne Diseases
Mosquitoes in Vermont
Prevent Mosquito Bites
Eastern Equine Encephalitis
Jamestown Canyon Virus
West Nile Virus
About Jamestown Canyon Virus
Jamestown Canyon virus is spread to people by infected mosquitoes. The virus is found throughout much of the United States, but most human cases are reported from the upper Midwest. Cases occur from late spring through mid-fall. You can reduce your risk by taking steps to
prevent mosquito bites
In 2025, the Vermont Department of Health started monitoring mosquito populations for Jamestown Canyon virus.
See the weekly surveillance report
Important Links
Jamestown Canyon (CDC)
National Data (CDC)
Mosquito Control at Home (CDC)
Symptoms
Most people with Jamestown Canyon don’t develop symptoms. Some may experience flu-like symptoms a few days to two weeks after a mosquito bite.
Common symptoms include:
Fever
Fatigue
Headache
You may also have:
Chills
Cough
Dizziness
Muscle aches
Nausea or vomiting
Runny or stuffy nose
Sore throat
People who have weak immune systems or who are older may be more likely to develop severe disease from Jamestown Canyon virus. About 50% of people who get sick are hospitalized.
Severe symptoms may include:
Confusion
Difficulty moving or speaking
Loss of coordination
Seizure
Sensitivity to light
Stiff neck
Treatment
There are no vaccines to prevent or medicines to treat Jamestown Canyon. For mild symptoms, your health care provider may recommend:
Fluids to prevent dehydration
Over-the-counter pain relievers to reduce headache and fever
Rest
If you develop severe symptoms, you may need to be hospitalized to receive IV fluids, medication and monitoring.
How it Spreads
Jamestown Canyon virus circulates in the environment between mosquitoes and animals, typically deer. Infected mosquitoes can then spread the virus to people and other animals by biting them. People are considered "dead-end" hosts. This means they do not spread the virus, even when they are sick, to mosquitoes that bite them. Jamestown Canyon virus is not spread by coughing, sneezing, touching, or other contact with someone who is infected.
Learn more about causes and how it spreads (CDC)
Information for Health Care Professionals
Most cases of Jamestown Canyon virus disease occur during April through September. Many Jamestown Canyon virus infections are asymptomatic, but the specific symptomatic-to-asymptomatic ratio is not known. Among patients who are symptomatic, initial symptoms are non-specific, including fever, fatigue, or headache. Some patients also report respiratory symptoms, such as cough, rhinitis, or pharyngitis. The incubation period for Jamestown Canyon virus disease is unknown but based on other arbovirus infections is likely 2-14 days.
Some patients with Jamestown Canyon virus disease might develop meningitis or encephalitis with possible meningismus, seizures, altered mental status, and cerebrospinal fluid (CSF) pleocytosis.
About half of known Jamestown Canyon virus disease patients have been hospitalized. However, deaths are rare and have been primarily reported in immunocompromised patients.
Information for health care professionals (CDC)
Topics:
Mosquito-borne Diseases
September 11, 2025