Two additional cases of Eastern equine encephalitis (EEE) have been documented by the Equine Disease Communication Center.
One case occurred in Portage County, Wisconsin, where a 4-year-old Standardbred mare, who had not been vaccinated, tested positive for EEE on Aug. 27. The mare displayed clinical symptoms starting on Aug. 18, which included fever, ataxia, lateral recumbency, and seizure-like activity. Tragically, she had to be euthanized.
The second case took place in Clare County, Michigan, involving an under-vaccinated yearling Quarter Horse colt. This colt tested positive for EEE after showing clinical signs on Aug. 13, such as falling and trembling. Unfortunately, he also had to be euthanized.
EDCC Health Watch is a marketing program from Equine Network that utilizes data from the Equine Disease Communication Center (EDCC) to generate and distribute confirmed equine disease reports. The EDCC is an independent nonprofit organization that relies on industry donations to offer accessible infectious disease information.
EEE 101
Eastern equine encephalomyelitis is caused by the Eastern equine encephalitis virus, with wild birds serving as the natural reservoir. Mosquitoes that feed on EEE-infected birds can transmit the virus to humans, horses, and other birds. Horses do not develop high enough levels of these viruses in their blood to be contagious to other animals or humans. Due to the high mortality rate in horses and humans, EEE is considered one of the most severe mosquito-borne diseases in the United States.
Tips for preventing mosquito-borne diseases include:
- Avoid mosquito bites: Use insect repellent when outdoors, especially from dusk to dawn.
- Look for EPA-labeled products containing active ingredients such as DEET, picaridin (KBR3023), or oil of lemon eucalyptus (p-menthane 3,8-diol).
- Apply more repellent, following label instructions, if mosquitoes begin to bite.
- Mosquito-proof homes: Repair or install window and door screens, and cover or remove empty containers with standing water where mosquitoes can lay eggs.
- Protect your horses: Veterinarians recommend licensed vaccines against EEE for all horses in the U.S. Horses should be vaccinated at least annually (recommendations vary in high-risk areas). It’s not too late this year to vaccinate your horses.
- Use approved insect repellents to safeguard horses.
- If feasible, keep horses indoors during peak mosquito exposure times at dusk and dawn.
- Remove standing water, empty water troughs, and buckets at least weekly.
- Introduce fish that consume mosquito larvae in water tanks (contact local mosquito control for assistance), or utilize mosquito “dunks” (solid “donuts” of Bacillus thuringiensis israelensis, which are harmless to horses) available at hardware stores.