Eastern Equine Encephalitis (EEE) in Vermont

Poppy September 004Eastern Equine Encephalitis: The Real Danger to You and Your Horse.

River Road Veterinary Clinic has just been notified that a horse in Highgate, VT was euthanized on August 30 as a result of being infected with Eastern Equine Encephalomyelitis (EEE). Last year EEE caused the death of two people and a horse in Vermont. So far this year mosquitos in several parts of the state have tested positive for EEE, and the Vermont Department of Health is cautioning people that it’s quite possible EEE is present in ALL AREAS of Vermont, and precautions should be taken regardless of the area you live in.

EEE is a mosquito-borne, viral infection that can be found in wild bird populations, and can cause severe encephalitis (neurological disease) in horses, llamas, alpacas, and humans. The Eastern, Western, Influenza, Tetanus combination equine vaccine provides excellent coverage against EEE. Vaccination is the best tool to protect your animal from this devastating disease. All horses should be vaccinated annually! Care should also be taken to protect yourself and your animals from mosquito bites. This can include mechanical barriers such as fly sheets and face nets, using an appropriate insect repellant, emptying water troughs twice weekly and removing stagnant water to limit mosquito populations. The Vermont Department of Health is also advising people to take every possible precaution to avoid mosquito bites until the first killing frost (which occurs when the temperature drops to 28 degrees for several hours). In addition to the previous suggestions, these precautions include wearing long sleeves, pants, socks, shoes, and a hat and limiting the amount of time spent outside during dawn and dusk hours.

Eastern Equine Encephalitis circulates in wild bird populations without causing clinical disease. Disease is then transmitted to mammals through the bite of a mosquito that has previously fed on an infected bird. The virus cannot survive on environmental surfaces. Mammals are considered “dead-end hosts” who cannot transmit disease to others.

Birds infected with EEE can shed the virus in feces, blood, or vomitus. Humans may become infected through contact with the virus through mucous membranes and/or open wounds. Please use caution when handling sick live birds as well as carcasses.

Early symptoms of EEE in horses are often nondescript and can mimic other less serious disease. After about two days, a low-grade fever may develop. After four to five days symptoms can include fever, rapid heart rate, poor appetite, and depression. Muscle weakness, neurological symptoms, behavioral changes, dementia, aggression, head pressing, wall leaning, circling, blindness, twitching, facial paralysis, and seizures may develop as the disease progresses. 75-90% of infected horses enter a semi-comatose, convulsive state resulting in death. Surviving horses usually retain permanent damage to the nervous system.

Symptoms of EEE in people can include either an acute onset of chills, fever, malaise, and joint/muscle pain that lasts one to two weeks or a more serious form that affects the central nervous system and causes fever, headache, irritability, convulsions and coma. This form of EEE is fatal in 35% of people affected. EEE does NOT just affect people with weakened immune systems, and can cause illness in young, healthy people.

Please call River Road Veterinary Clinic at (802) 649-3877 or contact the Vermont Department with any questions or to report potential cases of Eastern Equine Encephalitis.

Vermont Health Department

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