The Register-Herald, Beckley, West Virginia

Local News

August 14, 2009

Official warns: Protect against West Nile virus

Fayette horse infected; more mosquito ‘pools’ testing positive

By Jessica Farrish

A horse in Fayette County tested positive for West Nile virus last month, and state Agriculture Commissioner Gus Douglass is warning horse owners to control mosquitoes around their animals.

No cases of humans with WNV have been reported.

Officials with the state Department of Health and Human Resources’ infectious disease epidemiology program are reporting a high number of WNV-positive mosquito pools compared to previous years.

A “pool” is a sample of mosquitoes from the same species that have been trapped in different traps and pooled together for testing, according to DHHR entomologist Greg Chrislip.

More than 90 mosquito pools in the state have tested positive this year.

The pools were drawn from Kanawha, Jackson, Ohio and Cabell counties, Chrislip said.

Testing has not been conducted in other counties, including Raleigh, Fayette, Summers, Nicholas, Monroe, Greenbrier, Pocahontas and Wyoming.

When asked if WNV could be present in those counties, Chrislip said it was possible.

“There very well could be (WNV mosquitoes),” he said. “We’d have to do trapping to see.

“We can’t say, ‘Yeah, there probably is,’ because we’d really have to look at the species that are there.

“Not every mosquito can carry every virus.”

It was unclear how the Fayette horse was infected with WNV.

WNV is virulent in horses, although not always fatal. There is no direct treatment for it.

Horse owners are advised to eliminate standing water around barns and other places animals gather and to remove old tires or poorly drained areas from their properties.

Most people who contract WNV experience no symptoms, but about 20 percent can have symptoms such as fever, headache, nausea and vomiting.

About 1 in 150 people can suffer a severe illness, which may involve high fever, stupor, coma, tremors, convulsions, vision loss and paralysis, according to the Centers for Disease Control Web site.

“I’m really surprised we haven’t seen any human cases, but we still have a long way to go,” Chrislip said. “A teaspoonful of standing water is enough for mosquitoes to breed, so the potential is definitely there.”

Chrislip advised using screens in doors and windows and to wear long sleeves and long pants when mosquito bites are likely.

The mosquito that carries WNV is most active at dusk and dawn, he said.

CDC recommends that people use bug repellent brands that contain either Deet, oil of lemon eucalyptus, Picaridin or IR3535.

Deet and Picaridin have proved most effective as repellents, according to CDC information.

— E-mail: jfarrish@register-herald.com

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