JOHN DAY - West Nile virus hit Grant County on Aug. 26, when blood work on a 9-year-old quarter horse in Mt. Vernon came back positive.
Colleen Robertson, veterinarian at Gambler Veterinary Clinic, drew blood on the horse Aug. 19 and received word from the Rocky Mountain Regional Animal Health Laboratory in Colorado a week later.
"Since the West Nile virus first came out, we have been drawing blood on horses. Though this is our first positive case," said Robertson. "In this case, the horse is doing OK."
Identity of the horse's owner has not been confirmed.
Recovery on horses is on an individual basis. It can be fatal.
The virus can effect the central nervous system and cause symptoms of encephalitis.
Signs include stumbling, hanging of lips, down and not rising, twitching, convulsions, weakness or paralysis of hind limbs.
Not all horses with clinical signs of encephalitis have West Nile virus.
Horse owners should contact a veterinarian if they witness any of the above signs.
"The virus is passed by mosquitoes, not by horse-to-horse, or horse-to-human contact," said Don Hansen, state veterinarian for the Department of Agriculture in Salem.
West Nile virus is an infection that lives in birds. It is spread when a mosquito feeds on an infected bird then bites a human or a horse. Birds cannot transmit the disease to humans, nor can it be transmitted through person-to-person contact.
"Most cases seen in Oregon, nine so far, all but one was not vaccinated," Hansen said.
West Nile vaccines may be purchased at the local veterinary clinic. The two-shot series includes a shot given immediately, three to six weeks later and then annually afterward. The shots cost $14.65 at Gambler Veterinary Clinic.
"The shots are for equines (donkeys, mules and horses). Dogs are really unaffected," Robertson said.
"Statistics in horses mimic humans and probably 80 percent that contract the virus don't show signs," said Hansen.
If people find a dead bird and are concerned about what to do with it, they should report it to their local health department. Grant County's Health Department can be reached at (541) 575-0429.