A sample of mosquitoes collected in Alburgh have tested positive for West Nile virus, the Vermont Dept. of Health reported August 18.

This is the first positive pool of mosquitoes of the 2022 surveillance season. A pool is a group of up to 50 mosquitoes of the same species and location. There have been no human cases of West Nile virus yet this year. The last confirmed case was in 2021.

West Nile virus is spread through the bite of an infected mosquito. Historically, the virus has been found in all counties of Vermont. Most people who are infected do not get sick from the virus, but it can lead to serious illness, such as encephalitis. Symptoms of illness can include fever, headache, body aches, joint pains, vomiting, diarrhea or a rash. People age 50 and older are at highest risk. If symptoms persist, contact your health care provider.

Mosquitoes from pools throughout Vermont are collected by the Agency of Agriculture, Food and Markets and tested at the State Public Health Laboratory. This interagency surveillance effort takes place each year to help keep Vermonters informed about the risk of mosquito-borne diseases, like West Nile virus and Eastern Equine Encephalitis (EEE). So far this season, 48,441 mosquitoes from 984 pools have been submitted for testing.

Since 2003, there have been 14 confirmed human cases of West Nile virus in Vermont. There have been no human cases of the more deadly Eastern equine encephalitis (EEE) since 2012.

“West Nile virus has been circulating throughout Vermont for years now, and we expect to find positive pools each season,” said State Epidemiologist Patsy Kelso. “We have been fortunate that not many people have developed serious illness. But West Nile, and especially EEE can be very serious, so, it’s important that Vermonters know and take the easy and quick steps to avoid getting bitten.”

The Health Department offers tips for preventing mosquito-borne diseases:

• Wear long-sleeved shirts and long pants when outdoors.
• Limit your time outside at dawn and dusk – when mosquitoes are more likely to bite.
• Use insect repellent labelled as effective against mosquitoes. The EPA has a tool to help find the right repellent for you.
• Cover strollers and outdoor playpens with mosquito netting.
• Fix holes in screens and make sure they are tightly attached to doors and windows.
• Get rid of standing water in spots like gutters, play pools, empty flowerpots and birdbaths. Mosquitoes breed in water that has been standing more than four days.

Horse owners are urged to consult with their veterinarians and make sure their animals are up to date on vaccinations for this and other vector-borne diseases. Horses cannot spread West Nile virus to humans or other horses, but it can cause neurologic disease and death in unvaccinated animals. In 2018 an unvaccinated horse died from the virus.

For more information about mosquito surveillance, diseases and prevention, visit healthvermont.gov/mosquito.