2nd horse identified with Eastern Equine Encephalitis in St. Lawrence County

CANTON, NY — The St. Lawrence County Public Health Department has been notified that a horse in the Brasher Falls area has tested positive for Eastern Equine Encephalitis (EEE, Triple E) virus. The EEE virus is transmitted by mosquitoes and can infect people, horses, and other mammals, some birds, reptiles, and amphibians. This very rare, but serious, virus can cause inflammation of the brain, also known as encephalitis. It is important to consult a trusted veterinarian about vaccinating horses against EEE.

EEE vaccination is very effective at preventing clinical disease in horses. Vaccination needs to be repeated at minimum on an annual basis; consult with your veterinarian regarding boosters. To reduce exposure to mosquitoes for horses: eliminate any standing water (mosquito habitat) and place fans inside where the horses rest, limit outdoor activities at dawn and dusk, and use equine approved mosquito repellent.

This week, the Franklin County Public Health Department was notified that a horse in the Moira area tested positive for EEE. Earlier this month, another horse in Brier Hill also tested positive. About 5-10 EEE human cases are reported each year in the U.S. In New York State, there have been 8 human disease cases between 2003-2022. These cases occurred in Oswego and Onondaga counties.

To avoid mosquito breeding near your property, the St. Lawrence County Public Health Department advises taking the following measures. Make sure your roof gutters drain correctly and clean clogged gutters in the spring and fall. Remove or turn over any items that may hold stagnant water, such as tires, buckets, planters, toys, pools, birdbaths, flowerpots, or trash containers to prevent mosquitoes from breeding. Clear vegetation and waste from the edge of ponds.

To avoid mosquito bites, take precautions during their peak activity hours from dusk until dawn. Wear long pants, a long-sleeved shirt, socks, and shoes. Use mosquito repellent containing DEET, Picaridin, Oil of Lemon Eucalyptus, or IR3535. Do not apply repellent directly to children; instead, apply it to your own hands and then rub it onto your child. Avoid applying to your face and wash your skin and clothing thoroughly after coming indoors.

For more information on EEE, please call the St. Lawrence County Public Health Department at 315-386-2325 or visit:

New York State Department of Health’s website:

Center for Disease Control website:

U.S. Department of Agriculture’s website: