Horses in Brunswick and Granville counties in North Carolina are the first equine in the state to test positive for West Nile Virus, while 13 horses — mostly in the southeastern part of the state — have been confirmed with Eastern Equine Encephalomyelitis.

Both viruses are spread by infected mosquitoes and can affect both equine and humans. To date there have been no reported human cases of either disease.

EEE has been confirmed in equines in Pender, Onslow, Cumberland, Robeson, Columbus, Wayne, New Hanover, Brunswick and Yadkin counties. The positive horse in Yadkin County is of interest because traditionally the disease is seen in the eastern part of the state.

“Both diseases are appearing earlier than normal, which is alarming for horse owners,” said State Veterinarian Dr. David Marshall. “With West Nile established in all 100 counties and EEE confirmed across a large area, equine owners are strongly advised to vaccinate horses, mules, ponies and other equine against these viruses. Vaccinations do not fully protect the animal until at least three to six weeks after a second booster shot, so the shots need to be given right away to give the animals some protection during the most active portion of the mosquito season.”

About 30 percent of infected horses die from WNV, despite supportive treatment. EEE poses a greater risk, with fatalities approaching 90 percent of the equine that show signs of the disease. Many animals that survive EEE are permanently impaired. Emus are also highly susceptible to EEE and emu owners should consult with their veterinarians to discuss vaccinating the birds.

Symptoms of WNV in horses can include loss of appetite and depression, fever, muscle twitching, weakness or paralysis of hind limbs, convulsions, impaired vision or hyperexcitability.

Symptoms of EEE, also known as “equine sleeping sickness,” include impaired vision, aimless wandering, head pressing, circling, inability to swallow, irregular staggering gait, paralysis, convulsions and death. These symptoms are difficult to distinguish from those of West Nile and are also similar to rabies, which makes it imperative that veterinarians seek a definitive diagnosis from a certified laboratory.

Mosquitoes can breed in any puddle that lasts for more than four days. All North Carolina residents are asked to remove sources of standing water to reduce the chance of exposing animals and people to WNV or EEE.

For more information about these diseases and mosquito prevention tips, go to the North Carolina Department of Agriculture and Consumer Services' Veterinary Division Web site at www.ncagr.com/vet/DiseaseAlerts.htm. Veterinarians are required by state law to report confirmed cases of WNV and EEE to the State Veterinarian's office at (919) 733-7601.