Michigan's Upper Peninsula Reports Equine EEE Cases

Michigan's Upper Peninsula Reports Equine EEE Cases

A viral disease, EEE affects the central nervous system and is transmitted to horses by infected mosquitoes.

Photo: iStock

The Michigan Department of Agriculture and Rural Development (MDARD) reported Oct. 11 that the state’s Upper Peninsula has confirmed its first two cases of a mosquito-transmitted equine disease this year.

In a statement on its Facebook page, the MDARD said two horses from different farms in Marquette County tested positive for Eastern equine encephalitis (EEE). Both horses—a 25-year-old Quarter Horse gelding and a 11-year-old Quarter Horse gelding—were unvaccinated and have been euthanized.

“These horses bring the total number of reported cases of EEE in Michigan for 2017 to six: two from Marquette County, two from Clare County, one from Roscommon County, and one from Wexford County,” the MDARD said.

A viral disease, EEE affects the central nervous system and is transmitted to horses by infected mosquitoes. Clinical signs of EEE include moderate to high fever, depression, lack of appetite, cranial nerve deficits (facial paralysis, tongue weakness, difficulty swallowing), behavioral changes (aggression, self-mutilation, or drowsiness), gait abnormalities, or severe central nervous system signs, such as head-pressing, circling, blindness, and seizures. The course of EEE can be swift, with death occurring two to three days after onset of clinical signs despite intensive care; fatality rates reach 75-80% among horses. Horses that survive might have long-lasting impairments and neurologic problems.

Health Alert: EEE, WEE, VEE

Vaccines have proven to be a very effective EEE prevention tool. Horses that have been vaccinated in past years will need an annual booster shot; in areas with a prolonged mosquito season, veterinarians might recommend two boosters annually—one in the spring and another in the fall. However, if an owner did not vaccinate their animal in previous years, the horse will need the two-shot vaccination series within a three- to six-week period.

In addition to vaccinations, horse owners also need to reduce the mosquito populations and their possible breeding areas. Recommendations include removing stagnant water sources, keeping animals inside during the bugs’ feeding times, which are typically early in the morning and evening, and applying mosquito repellents approved for equine use.

About the Author

Erica Larson, News Editor

Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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