Understanding and Preventing Sleeping Sickness

— Written By and last updated by Patricia Burch

Since we have seen several cases of Eastern Equine Encephalomyelitis (EEE) in the area this summer, I thought it may be helpful to spend a few minutes reviewing the disease, how it affects horses, and how it can be prevented.

Encephalomyelitis, or commonly known as sleeping sickness, is a disease of the nervous system in horses, but can also be a threat to humans. There are three strains of the disease, Eastern, Western, and Venezuelan. Horses are the last host in the Eastern and Western strain, so disease will not spread from them. The Venezuelan strain can spread from horse to horse or horse to human. Mosquitos are the primary vector which transmits the disease, while birds and wild animals can carry the disease and act as a reservoir.

Possible symptoms of the disease are fever, neurological problems, such as wandering, staggering, vision problems, droopy lip, and teeth grinding. Paralysis may occur with disease progression. Slow recovery may occur over several weeks, but each strain of encephalomyelitis may be fatal. Unfortunately, over 90% with EEE will die, 25-50% with WEE, and 75% with VEE. There is no treatment for the disease, other than supportive veterinary care.

What’s most important to remember is that Encephalomyelitis is preventable, through vaccination. It is recommended to vaccinate twice a year (spring and fall) for EEE in our region of the US. Vaccines are highly effective, affordable, and may be combined with other vaccines. Vaccines are readily available at many feed and animal health supply stores and are certainly available through large animal or equine veterinarians. Please make sure to schedule a fall and spring vaccination for your equines, every year, and follow your veterinarian’s advice.