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Mosquitoes test positive for EEE in Vermont for first time in years

A cartoon illustration of a mosquito biting a hand
nicoletaionescu/Getty Images/iStockphoto
Mosquitoes in Grand Isle and Franklin counties have tested positive for Eastern equine encephalitis, according to the Vermont Department of Health.

Mosquitoes in two Vermont counties have tested positive for a serious and potentially fatal mosquito-transmitted infection, for the first time in eight years.

The health department says mosquitoes collected in Grand Isle and Franklin Counties have tested positive for Eastern equine encephalitis, or EEE.

“It’s sort of big news, in that it’s a potentially very awful illness,” said Patti Casey, whoruns a surveillance program with the Vermont Agency of Agriculture.

Casey added that Vermont is the first state in New England to report finding EEE this year

More from Vermont Public: It's not your imagination: There are more mosquitoes in Vermont this summer.

For most people with EEE, symptoms are similar to the cold or flu.

But the disease can result in severe illness — including encephalitis, an inflammation of the brain that can be fatal.

And while there’s a vaccine against the disease for horses, that’s not the case for people.

“There is no specific treatment or vaccine in humans, it’s all supportive care if you get ill,” said Dr. Natalie Kwit, a public health expert and veterinarian with the Vermont Department of Health.

The virus was first detected in Vermont in 2011 in a flock of emus, and in subsequent years several horses and two people in Vermont died from infections.

The past few summers have been fairly dry, and mosquitoes — and the diseases they carry — have been less numerous.

“This year is, notably, a lot worse,” said Casey.

Earlier this month, West Nile virus was also found in mosquitoes in Alburgh and Vergennes.

Other states across the region have also seen an uptick in mosquito numbers thanks to wet weather, Casey added, but not quite like what's been recorded in Vermont. “I think we might be winning the prize for just the bump in numbers.”

A man bends over a black box in the winds, holding a vacuum contraption.
Patti Casey
Vermont Department of Agriculture
Every week, state workers vaccuum out mosquitoes from traps that target Culiseta melanura, the primary species that carries EEE.

Mosquitoes thrive in wet conditions, when they have more opportunity to lay eggs, including the primary species that carries this virus, the blacktailed mosquito or Culiseta melanura,

“It needs a fairly high water table,” Casey explained. “It breeds and lays eggs in these funny little places that are sort of hard to reach in swamps, like under tree roots and stuff. And all of this water is just making it a very successful year.”

Those particular mosquitoes do not bite people, only birds. But when other mosquito species bite an infected bird, they can pick up the virus, then transmit the disease to people and mammals.

Now, Casey’s team is ramping up their testing efforts — adding four more traps sites, for a total of 109 across the state they visit at least weekly.

At the same time, the state health department is amplifying their messaging.

“We want everyone to be taking precautions against mosquito bites right now,” said Kwit, with the Department of Health.

That includes wearing long sleeves and pants, limiting time outside at dawn and dusk, using repellent labeled as effective against mosquitoes, repairing screens, and getting rid of standing water around your home.

“I’m hopeful we keep these cooler evening temperatures,” Kwit said. “Naturally people are less likely to get bitten by mosquitoes by staying covered during those times of day when mosquitoes might be more active.”

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Updated: August 23, 2023 at 3:28 PM EDT
This article was updated Aug. 23 with interviews and more details on EEE in Vermont.
Brittany Patterson joined Vermont Public in December 2020. Previously, she was an energy and environment reporter for West Virginia Public Broadcasting and the Ohio Valley ReSource. Prior to that, she covered public lands, the Interior Department and forests for E&E News' ClimateWire, based in Washington, D.C. Brittany also teaches audio storytelling and has taught classes at West Virginia University, Saint Michael's College and the University of Vermont. She holds degrees in journalism from San Jose State University and U.C. Berkeley's Graduate School of Journalism. A native of California, Brittany has fallen in love with Vermont. She enjoys hiking, skiing, baking and cuddling with her rescues, a 95-pound American Bulldog mix named Cooper, and Mila, the most beautiful calico cat you'll ever meet.
Lexi covers science and health stories for Vermont Public.
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