Mosquitoes that feed on EEE-infected birds can transmit the virus to humans, horses, and other birds. | Photo: Photos.com

The Michigan State Department of Agriculture and Rural Development (MDARD) issued a statement saying that a 15-year-old unvaccinated Quarter Horse mare began showing clinical signs of Eastern equine encephalitis (EEE), including fever and head-pressing, on Aug. 18. She was euthanized, and on Aug. 28 test results confirmed her positive for EEE. This case is in addition to the 5-year-old Quarter Horse mare from Kalamazoo County that was euthanized Aug. 11 due to EEE.

EEE 101

Eastern equine encephalomyelitis is caused by the Eastern equine encephalitis virus, for which wild birds are a 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. Because of the high mortality rate in horses and humans, EEE is regarded as one of the most serious mosquito-borne diseases in the United States.