SPOKANE, Wash. (AP) — A viral disease stoked by drought has killed hundreds of deer on both sides of the Washington-Idaho border, wildlife officials say.

The disease, known as bluetongue, has killed mostly white-tailed deer but has also infected mule deer and one bighorn sheep in Idaho.

Cases have been confirmed in eight Eastern Washington counties and four counties in the Clearwater region of Idaho.

The disease will continue until a hard frost kills the gnats that carry it, Washington’s state wildlife veterinarian, Kristin Mansfield, told the Spokesman Review.

Bluetongue is closely related to epizootic hemorrhagic disease (EHD), which is common in whitetails in September but usually on a small scale in isolated areas, Mansfield said.

Wildlife officials are especially concerned that this year’s outbreak is the bluetongue variety of hemorrhagic disease, which can affect a wider range of animals, and that it’s significantly more widespread than in the past.

Experts say 80 to 90 percent of whitetail deer that get the virus will die.

At least 68 whitetails dead from bluetongue have been collected in the town of Colville, said Terry LeCaire, manager of the city’s streets department. A Washington State University lab has confirmed bluetongue virus in 45 whitetail samples submitted from Washington and Idaho, plus a handful of mule deer. Several landowners have also reported dozens of dead deer on their property.

Idaho Fish and Game Department officials have been fielding reports of dead whitetails for weeks from Moscow to Grangeville, said Jen Bruns, department spokeswoman in Lewiston.

“We’re finding dead whitetails just about any place the deer get around mud, which is where the gnats are produced,” said Michael Atamian, a Washington Fish and Wildlife biologist in Spokane.

Significant Eastern Washington EHD outbreaks also coincided with drought conditions in 1988 and 2004, said Woody Myers, a Washington Fish and Wildlife research biologist.

Whitetails in the Kamiah, Idaho, area required at least three years to rebuild populations after a major EHD outbreak in 2003.

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Information from: The Spokesman-Review, http://www.spokesman.com