By STEVE BROWN
A Washington state horse was euthanized this week after it contracted West Nile virus, and four other horses in Idaho and Oregon were diagnosed with the disease.
Veterinarians are urging horse owners to vaccinate their animals.
A 2-year-old gelding in Yakima County, Wash., was put down after it contracted the virus and its condition worsened, Washington state veterinarian Leonard Eldridge said. Confirmation of the illness came from the Washington Animal Disease Diagnostic Laboratory in Pullman.
The horse, which was pastured near Grandview, had no history of travel out of the area and had not been vaccinated for the virus.
That case follows on the heels of one horse in Klamath County, Ore., and three in Idaho testing positive for the virus in the past few weeks, marking its spread across the Northwest.
Mosquitoes have tested positive for the virus in Oregon, and confirmed cases of the virus in humans and horses have been reported in 10 southern Idaho counties.
The national mortality rate for horses that acquire the disease is 36 percent, said Scott Leibsle, Idaho's deputy state veterinarian.
West Nile virus is spread by mosquitoes that have fed on an infected bird. The disease can sicken people, horses, many types of birds and other animals. It is not spread from horses to other animals.
During the 2009 outbreak, Washington led the nation with 72 cases in horses.
"Because we led the nation, we're aware there's risk even though there were no cases the last couple of years," Jason Kelly, communications director at the Washington State Department of Agriculture, said.
The virus has been discovered in mosquito pools in the state, he said, and animal owners need to be reminded about the importance of vaccinations. "There's no room for complacency."
Horses initially need two doses, which cost about $30 each, and an annual booster vaccination is recommended in following years.
"We keep our horses vaccinated routinely and hopefully everyone else does, too," said Caldwell, Idaho, horse owner Connie Blayney, a member of the Idaho Horse Council's board of directors. "It's a really good vaccine, it's really effective and if you keep your horses vaccinated, you shouldn't have to worry about it."
According to the Centers for Disease Control and Prevention, 1,590 human cases have been reported in 43 states and the District of Columbia as of Aug. 28. Deaths now number 66, nearly half of them in Texas.
Most horses that contract West Nile do not become ill and show no symptoms. Those that do become ill have a loss of coordination, loss of appetite, confusion, fever, stiffness and muscle weakness, particularly in the hindquarters.
Mules, llamas and alpacas should also be vaccinated against West Nile, officials said.
Capital Press reporters Sean Ellis and Mitch Lies contribute to this report.