Skip to main content

Orleans County Horse Tests Positive for Eastern Equine Encephalitis

October 18, 2024
mosquito

Positive test is second equine case of EEE in Vermont this year. Horse owners encouraged to vaccinate.

Montpelier, VT — The Vermont Agency of Agriculture, Food and Markets received confirmation this week of a positive Eastern equine encephalitis (EEE) test in a horse. This case is in Orleans County, a location in Vermont that had not previously been identified as having any mosquitoes testing positive for EEE. It is the second horse testing positive this year. The horse was unvaccinated and is now deceased. The horse was tested on October 4. It likely contracted the disease mid-September during a period of warmer than normal weather.   

EEE, which spreads through the bite of an infected mosquito, is rare but can cause serious and life-threatening illness in people and some animals. Although the risk is lower as temperatures cool and mosquitoes are less active, prevention is still important. Until the first hard frost is recorded in your area, it is important to be aware of the risks associated with mosquito bites.  A hard, or killing frost, is defined meteorologically as two consecutive hours of temperatures below 28 degrees Fahrenheit.  Although mosquitoes are not killed until a hard frost occurs, they are extremely unlikely to be active when temperatures fall below 50 degrees in the evening.  You may wish to consider this information when making decisions about outdoor activities. 

Horse owners should consult with their veterinarians and make sure their animals are properly vaccinated for EEE, West Nile virus, and other viruses spread by infected insects or ticks. Horses cannot spread EEE or West Nile viruses to humans or other horses.

As noted, until the first hard frost in your area, Vermonters should continue to take steps to prevent mosquito bites and protect themselves from mosquito-borne illness:

  • Limit the amount of time you spend outdoors at dawn and dusk.
  • Apply repellent when you are going to be outdoors, especially at dawn or dusk. Use an EPA-registered insect repellent labeled as effective against mosquitoes. 
  • Wear loose-fitting long-sleeved shirts and long pants when outdoors.
  • Fix any holes in your screens and remove standing water around your home whenever possible.

Learn more about mosquito surveillance, visit: