For the second time in the last three weeks, a pool of mosquitoes found in Essex has tested positive for West Nile Virus, according to the Vt. Health Department.

Each year, the health department conducts weekly tests between June through October to track the prevalence of WNV in the state. Tests examine so-called pools – comprised of anywhere between one to 50 mosquitoes – that are collected by the Vt. Agency of Agriculture at the same trap on the same day. The health department has tested 55 pools in Essex this year, and twice the results have come back positive for WNV: once in August and again on September 3. Last year, the town had multiple positive tests as well. 

West Nile virus spreads when an infected mosquito bite a human or an animal, though it can’t be transmitted between the two. The disease doesn’t typically cause symptoms in most people: About 20 percent of those infected show some form of symptoms ranging from 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 virus has been detected in every county in Vermont since first popping up in the U.S. around the turn of the millennium, but only 12 cases of the disease in residents have been reported here since 2011. No human cases have been identified this year, the health department says. The department summarizes its data in a weekly report posted to its website (, and says more than 2,000 pools have been tested around the state so far this year. 

“We see West Nile virus in Vermont mosquitoes year after year, so it isn’t surprising to see this pool of mosquitoes test positive,” said Natalie Kwit, DVM, the state’s public health veterinarian, in a news release. “Luckily, we can take a few quick and easy steps to prevent mosquito bites and avoid West Nile virus and other diseases spread by mosquitoes.”

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.