North Carolina Confirms First EEE Cases of 2012

Two North Carolina Quarter Horses were euthanized this month after contracting Eastern equine encephalomyelitis (EEE), a mosquito-borne disease that is largely preventable in equine by vaccination.

The unvaccinated horses--a 2-year-old Robeson County mare and a 7-year-old stallion from Bladen County--exhibited signs of generalized weakness, stumbling, depression, and inability to stand or eat. The Robeson County horse's condition deteriorated so quickly that she was euthanized within 24 hours of first exhibiting clinical signs. The Bladen County stallion displayed signs for several weeks before being euthanized earlier this month; testing at Rollins Laboratory, in Raleigh, confirmed EEE this week.

They are the first reported cases of EEE in North Carolina horses this year. Last week, New Hanover County officials reported that EEE was found in a sentinel chicken flock.

"If your horses exhibit any symptoms of EEE, contact your veterinarian immediately," said State Veterinarian David Marshall, DVM. "Several serious contagious diseases, such as equine herpesvirus and rabies, have similar symptoms and should be ruled out."

A viral disease, EEE affects the central nervous system and is transmitted to horses by infected mosquitoes. Its fatality rate in 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. 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.

Marshall recommends that equine owners talk to their veterinarians about an effective vaccination protocol to protect horses from EEE and another mosquito-borne disease, West Nile virus (WNV). The EEE and WNV vaccinations initially require two doses for horses, mules, and donkeys that have no prior vaccination history.

Mosquitoes can breed in any puddle that lasts for more than four days, so removing any source of standing water can reduce the chance of exposing animals to WNV or EEE. Keeping horses in stalls at night, using insect screens and fans, and turning off lights after dusk can also help reduce exposure to mosquitoes. Insect repellents can be effective if used according to manufacturers' instructions.

People, horses, and birds can become infected from a bite by a mosquito carrying the diseases, but there is no evidence that horses can transmit the virus to other horses, birds or people through direct contact.

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