Mosquitos found in two different locations around Essex have tested positive for West Nile Virus, the Vt. Health Department announced last week.

The test marks the second time in less than two months that mosquitos carrying the virus were found in town; Essex’s first positive test was reported in early August. Though there have been no reports of human cases in Vermont so far this year, health officials learned last week a horse in Windham County had tested positive for the virus, according to a news release.

“Animal cases like this are cause for concern because it means mosquitoes carrying the virus are out there, and they’re biting,” said Natalie Kwit, a state public health veterinarian, in the news release.

Each year, the Vt. Agency of Agriculture conducts weekly tests between June through October to track the virus’ prevalence in the state. Tests examine so-called pools – comprised of anywhere between one to 50 mosquitos – collected at the same trap on the same day. The health department summarizes that data in a weekly report posted to its website (www.healthvermont.gov).

West Nile virus spreads when an infected mosquito bite a human or an animal, though it can’t be transmitted between the two.

The health department says the virus has been detected in every county in the state since first popping up in the U.S. around the turn of the millennium, but only eight cases of the disease have been reported in Vermont since 2011.

The disease doesn’t typically cause symptoms in most people: About 20 percent of those infected show some form of symptoms ranging from a fever, headache, body aches, joint pains, vomiting, diarrhea or rash, according to the Centers for Disease Control and Prevention. Most recover fully, but one in about 150 people develops a serious and sometimes fatal illness, with symptoms ranging from headache and high fever to convulsions and paralysis.

The state informs local health officers of any positive test results, and the health department is now working with municipalities on public outreach, providing language for local newsletters to spread awareness of how to avoid the disease.

Without a vaccination for humans, the answer is quite simple: Prevent mosquito bites. To do so, the health department offers the following advice:

• Use an EPA-registered insect repellent.

• Wear long-sleeved shirts and long pants when outside.

• Use permethrin to treat clothing and gear, such as boots, pants, socks and tents.

• Cover baby strollers or outdoor playpens with mosquito netting.

• Fix holes in your screens.

• Drain areas with standing water where mosquitoes can breed, like old tires, flowerpots, wading pools and rain gutters.

Kwit noted the risk of getting the virus is highest this time of the year and will continue to be until the first hard frost.

“Until then, it is peak season,” she said in a news release.