Vermont’s Department of Health confirmed the state’s first-known human case of the mosquito-borne Jamestown Canyon virus. The disease has relatively mild symptoms, especially for young people who do not have underlying health conditions.
The state began monitoring mosquitoes for Jamestown Canyon Virus this year, after it was found in nearby states. The monitoring showed insects in Rutland, Marshfield and Whitingham all carried the disease. This human case, which was confirmed in a Sept. 8 lab test in a Windsor County patient, further confirms the presence of the virus in Vermont, according to Natalie Kwit, the state’s public health veterinarian.
“It is a good indicator and reminder, just like anytime we find the virus in mosquitoes, to continue to take precautions against mosquito bites,” Kwit said.
Mosquitoes become infected when they bite animals — particularly deer — carrying the virus. They then spread it to other animals and people when they bite them. Humans are “dead end hosts,” meaning that the viral load people receive from an infected mosquito bite is too low to spread to other people.
It also means that many people with the virus never experience symptoms, while others can develop flu-like symptoms, such as fevers, headaches, chills and aches. People with compromised immune systems and older people are more at risk for more severe symptoms — for some, more serious disease could escalate to confusion and discoordination, stiffness and seizure. About half of people who do become symptomatic get hospitalized, according to the Department of Health.
The best way to prevent infection is to prevent mosquito bites in the first place. The Department of Health recommends limiting time outside during dusk and dawn when the insects are most active, wearing long sleeves and insect repellent, and covering windows, doors, playpens and strollers with tight mosquito nets or screens. The department also advises people to clear any standing water that may accumulate in things like pots, buckets or children’s outdoor toys.
In late summer, the risk for mosquito-borne illnesses increases, Kwit said, since there has been more time for the virus to circulate in hosts and mosquitoes. The risk remains — and the state plans to continue monitoring mosquitoes — until the first fall frost.
The state also tests the collected mosquito samples for West Nile virus and Eastern equine encephalitis — or EEE — virus, as it has in years past. There have been no confirmed cases of either in a human this year.
“We’re just learning about this virus, too,” Kwit said of Jamestown Canyon virus. “We’ve only just started actively testing for it in mosquitoes we collect in Vermont, so over time, we’ll get an understanding of where we’re finding it, as we’re gathering more evidence.”
