Chittenden County man contracts first human case of eastern equine encephalitis in Vermont since 2012

A man in his 40s from Chittenden County is the first detected human case of the rare eastern equine encephalitis in Vermont since 2012 , according to a joint press release issued Friday by the Vermont Department of Health and the Agency of Agriculture, Food & Markets.

“Unfortunately, we now have additional evidence that EEE virus is in mosquitoes that can infect humans, with the potential to cause serious illness,” said Dr. Mark Levine, the state’s health commissioner, in the release. “Please take mosquito prevention seriously as we continue monitoring this risk.”

The announcement comes a week after state health officials warned that mosquitoes tested positive for the eastern equine encephalitis virus in Grand Isle and Franklin counties. Additional mosquitoes collected from Colchester and Alburgh last week also tested positive for the virus Thursday, according to the release.

“Health officials are strongly urging people in three counties — Chittenden, Grand Isle and Franklin — to take extra measures to protect themselves from mosquito bites,” the release said.

Vermonters in affected areas are “strongly urged” to use mosquito-effective insect repellent, limit time outside at dawn and dusk when mosquitoes are more likely to bite, and wear clothing that covers arms and legs when outdoors.

Most people infected with eastern equine encephalitis will experience mild symptoms that may include fever, chills, fatigue, and joint and body aches, or no symptoms at all, the release said.

“While rare, EEE can result in severe disease, including encephalitis, an inflammation of the brain,” according to the release. The virus is fatal in about one-third of people who develop severe disease.

The two human cases of eastern equine encephalitis recorded in Vermont in 2012 were fatal.

The man, whose identity was not released to protect patient confidentiality, was hospitalized on July 16 and released from the hospital a week later, the release said. Laboratory testing by the health care provider detected the case, and a specimen submitted to the Centers for Disease Control and Prevention confirmed the presence of the virus on Thursday, according to the release.

As a result, the state is stepping up mosquito collection and testing to “better understand” virus activity, assess public risk, and evaluate additional options, which include “aerial or ground spraying of pesticides in areas where infected mosquitoes have been identified, should that be deemed the best course of action to protect public health,” the release stated.

Late summer into fall is when the risk of eastern equine encephalitis infection is highest, according to the release.

The state health department also suggests getting rid of standing water that may be sitting in gutters, tires, play pools, flower pots, and bird baths. Mosquitoes breed in water that has been standing for more than four days, according to the release.

Those with horses are urged to consult their veterinarians and ensure they are up to date on vaccinations. Although horses cannot spread eastern equine encephalitis or West Nile viruses to humans or other horses, they can suffer neurologic disease and death if infected and unvaccinated, according to the release. An unvaccinated horse in Vermont died from the virus in 2023 .

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