Press Releases



Connecticut Horse Confirmed Positive for Eastern Equine Encephalitis Virus

(HARTFORD, CT) – The Connecticut Department of Agriculture announced today the first equine case of Eastern equine encephalitis (EEE) for 2023.

The adult horse, which resided in New London County, began exhibiting neurological signs before being euthanized on October 1, 2023. Diagnostic samples collected and sent to the Connecticut Veterinary Medical Diagnostic Laboratory (CVMDL) at the University of Connecticut in Storrs have confirmed a diagnosis of EEE virus in the unvaccinated animal. 

EEE is not spread by horse-to-horse or horse-to-human contact. It is a viral disease transmitted through the bites of mosquitoes. The Connecticut Agricultural Experiment Station (CAES) has detected EEE-infected mosquitoes in 15 Connecticut towns this year – all in New London and Windham counties.  The risk for mosquito-borne diseases continues until the first hard freeze ends mosquito activity.

Equine owners are encouraged to implement the following, in coordination with their veterinarian, including:

  • Administering the initial two-dose vaccine series, four to six weeks apart
  • Administer regular boosters at least annually
  • Consult with your veterinarian if boosters are needed every six months
  • Give vaccinations at least one month prior to mosquito season to develop protective immunity
  • Remove sources of standing water to eliminate mosquito breeding grounds
  • Clean and refill water troughs regularly
  • Apply fly sprays containing pyrethrin regularly

If your horse is showing neurologic signs, i.e., hyperexcitability, tremors, convulsions, paralysis, head tilt, head pressing, incoordination, drowsiness, recumbency, colic, or death, it’s important to call a veterinarian to determine a diagnosis and treatment. 

Neurologic diseases of domestic animals, such as EEE, WNV, and Rabies, are reportable to the State Veterinarian at 860-713-2505. For more information, on animals and animal health, visit the state website.

The Connecticut Department of Agriculture mission is to foster a healthy economic, environmental, and social climate for agriculture by developing, promoting, and regulating agricultural businesses; protecting agricultural and aquacultural resources; enforcing laws pertaining to domestic animals; and promoting an understanding among the state's citizens of the diversity of Connecticut agriculture, its cultural heritage, and its contribution to the state's economy. For more information, visit

For Immediate Release: Wednesday, October 4, 2023 Contact: Rebecca Eddy,