Friday, June 30, 2006

Spread of West Nile virus increases

Officials warn to take proper precautions

Express Staff Writer

Horses are especially susceptible to contracting the West Nile virus, a disease first discovered in the U.S. in 1999 in the New York City area. Veterinarians say horse owners should make sure to vaccinate horses against the disease. Since its recent introduction, the equine West Nile vaccine has dramatically decreased the incidence of the virus's infection in horses. Photo by David N. Seelig

Cases of the West Nile virus are on the rise throughout Idaho, and public health officials in the state are advising that people take proper precautions to make sure they don't contract the infectious disease.

West Nile virus is an infection transmitted by mosquitoes that has spread rapidly and widely throughout the United States in the last three years. It was first discovered in 1999 in the New York City area.

The first confirmed case of the year in Idaho was discovered in mosquitoes in Gem County, in southwest Idaho, in June. Last year, the virus was discovered in 15 Idaho counties, infecting 13 people, more than 100 horses and a dozen birds, according to the Idaho Department of Health and Welfare.

To date, in Blaine County, signs of the virus haven't been as apparent, said Karin Frodin, a nurse epidemiologist with the Twin Falls office of South Central District Health. The discovery last year of an infected horse was the first known case of the virus in Blaine County, Frodin said.

So far, there have been no discoveries of the virus in humans or birds in the county, she said.

Still, the low incidence of West Nile in Blaine County shouldn't fool anyone into thinking that the virus hasn't made inroads into the area, Frodin said. For proof, all one has to do is look to Blaine County's southern neighbor, Lincoln County, where authorities last year found 14 cases.

The extra-wet weather Idaho experienced last winter may have something to do with this year's earlier-than-usual discoveries of virus-infected mosquitoes, Frodin said. In years past, the first discovery of West Nile in Idaho happened sometime in late July to early August.

This year's early-June discovery contrasts with last year, she said.

Up to 80 percent of people who contract the West Nile virus—typically those in good health and fewer than 50 years old—will either not know they have it or will feel mild flu-like symptoms, Frodin said.

People most susceptible to the virus are those over 50 years of age and those with suppressed immune systems. Frodin said those people "might run a fever, might have aches and pains and may seek medical attention."

Only one in 250 cases of infection result in severe medical complications like encephalitis, which is a swelling of the brain, and meningitis, she said.

"Be aware of the threat," she said. "Take precautions."

West Nile is not known to spread from person to person or from animal to person. Species most susceptible to the virus are horses and birds. Bird species especially susceptible to West Nile are raptors and members of the corvid family, which includes ravens, crows and magpies.

Unlike for humans, a vaccine has been developed for horses.

In Elmore County, one horse already tested positive this year for West Nile, the Idaho State Department of Agriculture announced June 23.

West Nile dos and don'ts

· Reduce standing water that provides mosquito breeding habitat.

· Insect-proof homes by repairing or replacing screens.

· Cover up exposed skin when outdoors.

· Apply insect repellent approved by the Environmental Protection Agency to exposed skin and clothing.

· Avoid mosquitoes when they're most active, at dawn and dusk.

· Report dead birds to the Idaho Department of Fish and Game.

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