The New York State Department of Agriculture and Markets (NYSDAM) confirmed on Aug. 15 that an unvaccinated 6-year-old mare of unreported breed in Oswego County began showing signs of Eastern equine encephalomyelitis (EEE) on Aug. 12. | Photo: Wikimedia Commons

The New York State Department of Agriculture and Markets (NYSDAM) confirmed on Aug. 15 that an unvaccinated 6-year-old mare of unreported breed in Oswego County began showing signs of Eastern equine encephalomyelitis (EEE) on Aug. 12. Signs included possible blindness, fever, staggering, and recumbency (inability to rise). The horse succumbed on Aug. 13.

The state’s first case, a vaccinated yearling mare also located in Oswego County, was humanely euthanized Aug. 13 after experiencing signs of ataxia, blindness, and dullness on Aug. 10. Officials confirmed her positive for EEE on Aug. 15.

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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