The Vermont Agency of Agriculture, Food, and Markets has received laboratory confirmation that a deceased horse in Franklin County tested positive for Eastern equine encephalitis (EEE) virus, the second in the county this year, the agency reported Sept. 12. The first EEE-positive horse, reported Sept. 4, was euthanized.

The two horses were located on separate properties, and these two cases represent the first time there has been evidence of EEE in Franklin County. In 2012, two people and two horses from southern Addison County and northern Rutland County died from EEE.

A viral disease, EEE affects the central nervous system and is transmitted to horses by infected mosquitoes. Clinical signs of EEE include moderate to high fever, depression, lack of appetite, cranial nerve deficits (facial paralysis, tongue weakness, difficulty swallowing), behavioral changes (aggression, self-mutilation, or drowsiness), gait abnormalities, or severe central nervous system signs, such as head-pressing, circling, blindness, and seizures.

The course of EEE can be swift, with death occurring two to three days after onset of clinical signs despite intensive care; fatality rates reach 75-80% among horses. Horses that survive might have long-lasting impairments and neurologic problems