On Oct. 18, the Michigan Department of Agriculture and Rural Development (MDARD) confirmed a 3-year-old Gypsy Vanner gelding positive for Eastern equine encephalomyelitis (EEE). Clinical signs began on Oct. 11 and included acting sleepy, eyes moving rapidly from side to side, and recumbency (down and unable to rise). The Kalamazoo County horse, which had been vaccinated regularly since weaning and was last vaccinated in spring 2019 by a veterinarian, was euthanized.

According to the Michigan State University (MSU) College of Veterinary Medicine, 27 equines are among the 31 laboratory-confirmed EEE cases in Michigan animals. Affected counties include:

• Allegan (1);
• Barry (2);
• Calhoun (1);
• Cass (2);
• Jackson (4);
• Kalamazoo (5);
• Kent (1);
• Lapeer (1);
• Livingston (1);
• Montcalm (1);
• Newaygo (1);
• Joseph (6); and
• Tuscola (1)

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