Horse got West Nile in Flathead
Vets say horse got West Nile here
New information has led local veterinarians to decide a horse put down for West Nile virus was infected in the Flathead.
Veterinarians Hugh Rogers and Pam Barker initially believed the horse was infected in Pondera County. However, they learned later that the animal arrived in the Columbia Falls area on Aug. 8, a time outside the virus incubation period.
The horse's owner called Rogers and Barker after the animal showed symptoms on Sept. 1. West Nile has an incubation period between three and 15 days, but most often a horse exhibits symptoms in seven days or less.
Blood drawn from the horse on Sept. 2 came back from the state laboratory as positive for West Nile virus on Tuesday, Sept. 14.
Kari Gabriel, Alpine Animal Hospital manager, alerted local media Wednesday to the new information.
"It means we have West Nile here, unfortunately," Gabriel said.
She said local clinics have a limited supply of the West Nile vaccine remaining if owners haven't yet protected their horses. According to the vaccine's distributor, a horse gains some protection from death after the first dose.
Horses receive the vaccine in two doses, three to six weeks apart, and then an annual booster to ensure immunity. Foals born late to vaccinated mares have some protection but should receive their own shots at 3 to 3 1/2 old.
Alpine and other clinics sell the vaccine to owners for about $16.50 a dose. If injected by clinic staff, Alpine charges $20.
"It's a bargain," Gabriel said.
Horses infected with West Nile commonly show weakness in the hindquarters with widened stance, stumbling, leaning, toe dropping and even paralysis. About one in 10 horses infected show symptoms of viral encephalitis and about one-third of these die.
The news of a West Nile case in Flathead County perplexed local health officials.
County health director Joe Russell said a state trapping effort has not found any West Nile-infected mosquitoes in Flathead County.
Mosquitoes that tested positive for West Nile virus were, however, trapped in Pondera County where the horse was purchased.
Russell said he agreed with the veterinarians' assessment regarding the incubation period.
"If I had a horse and I knew we had a reservoir of West Nile virus, I'd get my horse vaccinated tomorrow," Russell said.
He said the threat from West Nile virus to people and animals often peaks in September. However, the department has not observed or received complaints of a mosquito problem in the valley recently
The cold, rainy weather puts a damper on the insects. A hard frost ends the mosquito problem until spring.
Russell said the presence of the virus in the valley enhances the possibility of a West Nile virus threat to humans and animals next year.
In people, symptoms of West Nile virus mimic those of the flu: fever, headache, body aches and swollen lymph glands. Severe infections involve high fever, neck stiffness, muscle weakness, convulsions and paralysis.
About 80 percent of people infected notice no symptoms while 20 percent get mild flu-like symptoms. About one in 150 people develop a severe illness while one in 1,000 diagnosed die from West Nile virus.
People over 50 and those with compromised immune systems have the greatest risk for a serious encounter with the virus.
Reporter Candace Chase may be reached at 758-4436 or by e-mail at cchase@dailyinterlake.com