Wednesday, July 27, 2005

West Nile virus detected in horses

Gooding and Canyon counties report first cases this summer


By STEVE BENSON
Express Staff Writer

West Nile virus has appeared again in Idaho, according to the Idaho Department of Health and Welfare.

Mosquitoes tested in Canyon County, located in southwestern Idaho, tested positive for the virus last week. No cases in humans have been reported in Idaho yet this year but two horses have tested positive for West Nile virus, one in Gooding County and the other in Canyon County.

Last year, 22 horses and three people in Idaho tested positive for the virus, and experts believe this summer could be worse.

Karin Frodin, an epidemiologist for South Central District Health, which includes Blaine County, said case studies indicate West Nile usually becomes more severe the year after it has infected a certain area, as it can be passed on by breeding mosquitoes.

"We expect we will see a surge in human cases (in South Central Idaho) this year," Frodin said. Last summer, confirmed cases of the virus in the district included one person—in Gooding County—and 12 horses.

Dr. Steve Fairbrother, of the Wood River Equine Hospital, said the hospital has experienced a spike in phone calls from concerned horse owners since West Nile was reported in Canyon County last week. A vaccination is available for horses through a series of shots, but not for humans or other animals. Fairbrother said time is running out since it takes weeks for the vaccination to take effect.

Wood River Equine has been offering the vaccination for three years, and typically most horses receive their shots in the spring.

"This could be the year where we start seeing (infected mosquitoes) in the valley," Fairbrother said, adding that it's not too late to get a horse vaccinated.

About 80 percent of people infected by West Nile never suffer from any symptoms, and therefore are usually unaware they have contracted the virus. The rest typically suffer from mild flu-like symptoms, while a few experience severe effects that could include neurological damage or even death.

Frodin said the elderly and those with unusually weak immune systems, such as cancer patients undergoing chemotherapy treatments, are typically more susceptible to severe symptoms.

The incubation period is anywhere from 2-15 days, and the virus generally lasts about three to six days.

While the virus can be transmitted among mosquitoes through breeding, most mosquitoes contract the virus after feeding on migrating birds, Frodin said. The spread of West Nile has typically traveled from east to west across the United States, following bird migration paths, she added.

To help reduce the risk of contracting West Nile Virus, the Idaho Department of Health recommends applying insect repellent containing DEET or picardin to skin and clothing. Removing standing water from yards, such as puddles, bird baths and decorative ponds—prime breeding habitats for mosquitoes—will also help.

The Department of Health suggests people report dead birds to local Fish and Game offices.




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