UPDATE: Idaho confirms bluetongue-like outbreak killing whitetails in Clearwater region.  See post here.

WILDLIFE -- A deadly outbreak of bluetongue among Spokane-region white-tailed deer -- which I reported earlier this week -- has been officially confirmed by the Washington Department of Fish and Wildlife.

Although hundreds of deer may be dying from the disease in the state’s drought-stricken eastern region, wildlife managers say this year’s hunting seasons will not be affected.

WDFW veterinarian Kristin Mansfield said today that bluetongue is a common virus transmitted by biting gnats at water sources where deer congregate during dry conditions. Every year in late summer and early fall, some white-tailed deer are lost to bluetongue and a similar virus known as EHD (epizootic hemorrhagic disease).

She said the department does not know precisely how many deer have been affected, but reports are more widespread and numerous than in the past, probably because of the severe drought across the region.

After reading my story earlier this week, a rancher south of Spokane near Plaza called and said he'd confirmed at least 16 dead whitetails on his property in the past few weeks. "My neighbor has seen some, too, and there are likely many more," said Mike Proff. "But they disappear so quickly you can't make a good count. I found two dead next to each other one day. The next day I went out on my four-wheeler and they were gone, completely eaten by coyotes and scavengers."

As of Sept. 17, WDFW had received reports of suspected deaths from bluetongue or EHD in several portions of the department’s eastern region, which includes Asotin, Columbia, Ferry, Garfield, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla and Whitman counties.

Wildlife managers said the emergence of the disease will not affect this year’s hunting seasons.  Archery deer hunting season is under way, and muzzleloader and modern firearm seasons start in October.

WDFW officials say they will continue to monitor effects of the disease until it subsides. Mansfield said outbreaks usually end with the arrival of colder, wetter weather, when deer move away from gnat-infested areas, or by the first hard frost, which kills the disease-carrying gnats.

Report sick or deer likely to be dead from disease to:

• The department's regional office in Spokane, (509) 892-1001 or
• The department’s dead wildlife hotline, (800) 606-8768.

Bluetongue and EHD are spread by biting gnats, not from deer to deer, and are not transmissible to humans.  Nonetheless, WDFW discourages hunters from shooting and consuming animals that are obviously sick. Other wildlife species, including mule deer, are rarely affected.

Symptoms in the early stages include lethargy, disorientation, lameness, or unresponsiveness to the presence of humans. Later signs include excessive salivation or foaming at the mouth and a swollen tongue.

Mansfield said the disease often kills deer so quickly – within a day or two – that their bodies remain in good condition, but others may not die immediately but stop eating and become emaciated. 

The incubation period for these diseases is five to 10 days, so afflicted deer may be observed for a couple of weeks after the first hard frost of fall.