The Virginia Department of Agriculture and Consumer Services (VDACS) announced July 22 that it has confirmed the third case of Eastern equine encephalitis (EEE) in a Virginia horse this year.

In a statement on its Facebook page, the VDACS said the horse—a mare from Chesapeake—contracted the disease one day and died the next. The horse’s vaccination history is unknown.

The first two EEE cases in Virginia this year were both confirmed in horses residing in Suffolk.

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