Health Care

Mosquito species known for Zika transmission found in Vermont

A mosquito on a finger
An Asian tiger mosquito. Centers for Disease Control photo by James Gathany

A mosquito known to carry diseases like Zika has been identified for the first time in Vermont — though the ones here do not carry any viruses.

Eggs of the Asian tiger mosquito were identified by a state surveillance program in Windham County late last month.

“Seeing as their were eggs found, it does mean there were at some point adult females flying around,” said Natalie Kwit, a public health veterinarian with the Department of Health, in a press release.

Typically, the mosquito is a tropical or subtropical species. It is known to carry diseases like chikungunya, dengue and Zika, all of which can be passed on to humans. But Vermont is way outside its native range, according to the Department of Health.

Health officials say the state’s climate is pretty inhospitable for the species the majority of the year, making it unlikely that they will be spreading new diseases here “any time soon.”

“The diseases they can carry are not endemic to our area, and in fact are rarely found anywhere in the United States,” Kwit said.

But in Massachusetts, Kwit said there has been some evidence that the mosquitoes are overwintering. She said one theory is that those mosquitoes are being transported to Vermont inadvertently by car or truck.

Officials say it is too soon to tell if the mosquito’s presence is an anomaly, or if it will be an ongoing part of the state’s ecosystem. 

“The Asian Tiger mosquito population may not be able to survive a Vermont winter,” said Patti Casey, environmental surveillance program director with the Agency of Agriculture, Food and Markets, in a press release.

Casey said the state needs to continue watching the species, to see whether it will be able to overwinter as eggs, or return to Vermont in another manner.

The CDC reports that there is currently no local transmission of Zika in the continental United States, though it continues to be found in Puerto Rico. Dengue fever has only seen outbreaks in Hawaii, Florida and Texas, though officials note it is “extremely rare” in the U.S. And since 2015, there have been no locally acquired cases of the chikungunya virus.  

The Health Department noted that like the mosquitoes already in Vermont, the Asian tiger mosquito has been found to carry West Nile virus, and Eastern equine encephalitis, but is not considered a “primary vector” for the diseases.

The state’s mosquito surveillance program typically ends in mid-October, when the risk for mosquito-borne diseases declines, Kwit said. She noted that the identification of the new species is an important reminder of the public health challenges posed by climate change.

“Warming temperatures and changing precipitation patterns are affecting the suitability of Vermont’s habitat,” she said, “which can introduce insects, animals, and diseases that previously weren’t found in our area.”

But for now, she said, there’s no reason for Vermonters to be concerned.

“In the immediate present, it’s not a big concern at all,” Kwit said. “But this is something we should monitor. It’s just good for us to know in case we do have those diseases introduced into our area.”

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Ellie French

About Ellie

Ellie French is a general assignment reporter and news assistant for VTDigger. She is a recent graduate of Boston University, where she interned for the Boston Business Journal and served as the editor-in-chief of The Daily Free Press, BU’s student newspaper. She is originally from Duluth, Minnesota.

Email: [email protected]

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