Chittenden County Man Contracts First Human Case of Eastern Equine Encephalitis in Vermont Since 2012

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

“Unfortunately, we now have additional evidence that EEE virus is present in mosquitoes and can infect humans, with the potential to cause serious illness,” state Health Commissioner Dr. Mark Levine said in the statement. “Please take mosquito prevention seriously as we continue to monitor this risk.”

The announcement comes a week after state health officials warned that mosquitoes testing positive for the Eastern equine encephalitis virus had been detected in Grand Isle and Franklin counties. Additional mosquitoes collected in Colchester and Alburgh last week also tested positive for the virus Thursday, the statement said.

“Health officials are strongly urging residents in three counties – Chittenden, Grand Isle and Franklin – to take extra steps to protect themselves from mosquito bites,” the statement said.

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

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

“Although rare, EEE can cause serious illness, including encephalitis, an inflammation of the brain,” the statement said. The virus is fatal in about a third of people who develop serious illness.

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

The man, whose identity is being withheld to protect patient privacy, was hospitalized on July 16 and released a week later, the statement said. Lab tests conducted by the health care provider detected the case, and a sample submitted to the Centers for Disease Control and Prevention confirmed the virus on Thursday, the statement said.

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, if that is deemed the best course of action to protect public health,” the statement said.

According to the press release, the risk of infection with eastern equine encephalitis is highest from late summer to autumn.

The state Department of Health also suggests getting rid of standing water, which can be found in gutters, tires, play pools, flower pots and bird baths. Mosquitoes breed in water that has been standing for more than four days, the release said.

Horse owners are encouraged to consult their veterinarian and make sure their vaccinations are up to date. While horses cannot transmit Eastern equine encephalitis or West Nile virus to humans or other horses, they can suffer neurological disease and die if infected and not vaccinated, the release said. An unvaccinated Vermont horse died from the virus in 2023.