Chronic wasting disease discovery troubling


SUBLETTE COUNTY – The recent discovery of the county’s first mule deer to test positive for the incurable chronic wasting disease (CWD) is bad news – but not yet catastrophic – for local wildlife.
On March 27, Wyoming Game and Fish Department’s (G&F) Scott Edberg announced the positive CWD testing of the doe, which was found dead in February and taken away by a G&F technician conducting increased CWD surveillance in Sublette, Lincoln and Teton counties.
Discovering CWD in deer this far west in the state has been reluctantly anticipated and “is very unfortunate and concerning,” Edberg related.
“This deer was reported to G&F personnel after it was found dead in a resident’s yard south of town (near the Pinedale airport) late in February,” confirmed G&F Pinedale wildlife supervisor John Lund.
This winter, the harshest in decades, swept over the Upper Green and Hoback river basins, weakening and bringing down many mule deer and other wildlife unable to thrive or survive.
“This was during the time we were receiving many calls about dead deer succumbing to winter conditions,” he added. “It is unknown whether this deer actually died from CWD itself, the severe winter, or a combination of both.”
CWD, which was first identified in 1985 in southeastern Wyoming mule deer, is not only a rare, chronic and fatal neurological disease – it can also transmit to other cervids such as white-tailed deer, moose and elk, Edberg said.
As spongiform encephala, CWD is closely related to mad-cow disease in that they passed by mutated proteins called “prions” found in an infected animal’s saliva, feces or even a carcass.
“Prions are very resilient and can survive in a wide variety of environmental conditions and substrates for a considerable long time,” explained Edberg.
At this time, prions are unaffected by vaccines or known treatments. They will bind to contaminated soil and be move into and bind to plants grown in that soil – possibly transmitting these diseased prions into grazing animals.
While that might sound potentially catastrophic, Lund said one dead mule deer does not make an epidemic.
“We are certainly disappointed to find a CWD-positive deer in the area; however its detection is far from catastrophic to local deer populations at this point,” he said. “Continued intensive monitoring of deer, elk and moose in the area will allow us to evaluate if prevalence rises or if this is an isolated case. As CWD continues to spread across the state, increased monitoring became a priority and will continue in the Pinedale and Jackson regions in 2017.”
Lund said it wasn’t known if the dead deer, found in Hunt Area 139, was on its own or moving with a group: “There were some isolated small groups of deer in the area throughout the winter but we do not know if this one was in contact with them.”
In its 2016 management plan, Game and Fish prioritized increasing surveillance this winter in western Wyoming “so we can better understand the distribution of CWD there,” said Edberg, G&F deputy wildlife division chief. “This winter has had the most intense post-hunting season monitoring we have conducted for CWD in western Wyoming to date.
“It does let us know that the added surveillance has yielded valuable information. We will continue our increased level of monitoring in and around the new CWD positive area, including testing and removal of any animals showing clinical symptoms of CWD or animals we find dead that are suitable for testing.”
These increased surveillance efforts focus in the area around western Wyoming’s G&F winter elk feedgrounds and big-game winter ranges, with extra personnel in the Pinedale and Jackson regions.
That will include removing and testing “any animals showing clinical symptoms of CWD or animals we find dead that are suitable for testing,” he said on March 28. At this time, G&F is not considering killing game for additional tests.
“There are no plans to cull additional deer, elk or moose, but the department, especially with emphasis in the Pinedale and Jackson Regions will continue to collect and test samples for CWD from deer, elk and moose found dead or that are euthanized to due sickness or injury,” Edberg said. “In April 2016, the Department implemented a revised CWD management plan. This plan outlines and provides direction on the Department’s efforts to address the spread, prevention and management of CWD.”
G&F surveys game hunters and since Jan. 1, 2016, CWD technicians have tested 228 deer, 147 elk and 28 moose from the Pinedale region with “similar efforts” in Jackson.
The public is asked to report to G&F any deer, elk or moose that acts sick, although CWD symptoms are not obvious early on.
“Affected animals show progressive weight loss, reluctance to move, excessive salivation, droopy ears, increased drinking and urinating, lethargy and eventually death,” states the G&F’s CWD information page. “Animals will test positive for the disease long before these clinical signs appear and the majority CWD positive animals that are harvested appear completely normal.”
All in all, the Sublette and Wyoming Range mule deer herds – and even small groups overwintering in and around towns – have endured an extremely difficult winter, which is already showing its toll as G&F biologists venture onto the ranges.
Lund confirmed that not one of 26 fawns in the Wyoming Range herd, radio-collared soon after birth in summer 2016, survived the winter. Those 26 are “a small sample size and there are still a few fawns left; however, we anticipate overall fawn mortality (over this winter) to be extreme.”
Lund added, “As far as winter mortality on deer, this winter has obviously been a tough one. As the snow melts and deer begin moving from winter ranges toward the mountains, we will be doing surveys to compare fawn numbers pre and post-winter to get a more accurate estimate of mortality.”
Biologists will undertake these surveys in the near future for more accurate numbers, Lund said.
For more detailed information about the history and status of chronic wasting disease in Wyoming and links to studies about CWD management, prions and wildlife, go to https://wgfd.wyo.gov and find “CWD in Wyoming wildlife” under “wildlife disease” in the “Wildlife in Wyoming” section.

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