The Michigan Department of Agriculture and Rural Development (MDARD) announced Sept. 15 the first fatality associated with Eastern equine encephalitis (EEE) in an unvaccinated Midland County horse. Lab tests conducted by the Michigan State University Diagnostic Center for Population and Animal Health confirmed the EEE diagnosis. EEE is spread by mosquitoes, causes inflammation of the horses’ brains, and leads to death in many confirmed cases.

"There are vaccines available to aid in the prevention of the disease in horses," said Steve Halstead, DVM, Michigan state veterinarian. "These products are safe and effective …. Because of the risks associated with our plentiful mosquito populations, and known wild bird reservoirs of the EEE virus, all Michigan horses should be vaccinated. Unfortunately, that was not the case for this horse

"Horses are sentinels for EEE," Halstead continued. "Reports of illness in horses usually precede illness in people by days or weeks, so the reports serve as early warning that the human population needs to take precautions against mosquitoes."

A viral disease, EEE affects the central nervous system and is transmitted to horses by infected mosquitoes. The fatality rate for EEE-affected horses is 75-95%. The course of EEE can be swift, with death occurring two to three days after onset of clinical signs despite intensive care. Horses that survive might have long-lasting impairments and neurologic problems