An attending veterinarian in Texas euthanized a Montgomery County horse after it presented with neurologic signs. | Photo: Wikimedia Commons

An attending veterinarian in Texas euthanized a Montgomery County horse after it presented with neurologic signs. Testing confirmed the 14-year-old Appaloosa gelding positive for Eastern equine encephalomyelitis (EEE) on Aug. 26. The horse, which had been rescued six weeks prior to presentation, had an unknown vaccination history.

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.