As CWD spreads, testing and management plans increase

Posted 4/9/19

Chronic wasting disease is killing deer and threatening other ungulates across Wyoming — and the more scientists look for CWD, the more of it they find.

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As CWD spreads, testing and management plans increase


Chronic wasting disease is killing deer and threatening other ungulates across Wyoming — and the more scientists look for CWD, the more of it they find.

At the Wyoming Game and Fish Commission's meeting in Cody last month, Game and Fish Wildlife Veterinarian Mary Wood spoke about the serious problem that CWD poses in the state.

It’s a fatal disease of the central nervous system that affects mule deer, white-tailed deer, elk and moose, according to the Wyoming Game and Fish Department. The disease belongs to the group of rare diseases called transmissible spongiform encephalopathies (TSEs). These disorders are caused by abnormally folded proteins called “prions.” Evidence suggests CWD is transmitted via saliva, urine, feces or even infected carcasses. Animals may also be infected through feed or pasture contaminated with CWD prions — which can persist in the environment for many years.

Disease keeps spreading

Cases of CWD were found in several new hunt areas in 2018. Most notable was a case found in a road-killed mule deer in Grand Teton National Park.

But Wood said finding CWD in new areas is no surprise. The department has been upping surveillance over the past three years — and finding the disease in new places often is simply a matter of looking. Meanwhile, in some areas where CWD is already known to exist, new testing shows the prevalence of the disease has increased, Wood said.

One of the areas of concern is in the southwestern part of the Bighorn Mountains. In Hunt Area 164, prevalance was more than 40 percent last year, said Corey Class, wildlife management coordinator for the Cody region.

“When prevalence gets that high, we worry,” Class said.

New research also shows the disease is more prevelant in mature mule deer bucks than in does and young bucks.

“The question is; what happens to those bucks over a long period of time?” Wood said. “In talking with managers on the ground, working in areas with populations with high prevalence … areas where we’ve seen a lot of disease pressure for a long time, we’re noticing some disturbing trends.”

There are fewer mature bucks — a visible difference in how many big, mature bucks are being seen. Combined with matching data from the past few years, the reports from managers are of great concern to Wyoming scientists.

Game and Fish personnel tested the most CWD samples in the history of the program last year — testing more than 5,800 animals, Wood said.

“It has been an incredible effort by our folks,” she said. “It takes a lot of time with boots on the ground.”

Yet, even at a record pace, the number of samples is limited by the budget to pay for testing of the samples.

“The reality is even 6,000 samples, when you’re trying to survey white-tailed deer, mule deer, moose and elk in the entire state, doesn’t end up being a lot of samples,” Wood said.

Limited management

So far, management of the disease is limited. Scientists are studying ways to decrease prevalence, but are still in the preliminary phase of deciding on management tools. One important tool is long-term surveillance, to track the effects of the disease on herds over time. Another is to continue looking for CWD in areas where it has yet to be found; there are several areas in the state — including some in the Big Horn Basin and hunt areas close to Powell — where there hasn’t been enough testing to make any conclusions on prevalence.

In yet another effort to get a handle on managing the disease, the Game and Fish is partnering with the Ruckelshaus Institute, a division of the Haub School of Environment and Natural Resources at the University of Wyoming. The goal is to start a statewide CWD working group to develop recommendations for management. The working group will be comprised of a diverse group of stakeholders to collaborate and help scientists.

Applications were due Friday and participants will be selected soon. The group will work closely with Game and Fish scientists, studying data and looking for management recommendations.

Game and Fish wildlife officials are also scheduling a series of public presentations in May. The closest gathering is set for Worland, as the area has the highest prevalence of CWD in the Big Horn Basin.

(Editor's note: An earlier version of this story incorrectly said that Game and Fish Commission Vice President Pete Dube made a motion at the Cody meeting to increase the department's budget for testing for the disease by 50 percent. Although the commission heard testimony on chronic wasting disease and considered the effects of a budget increase, Dube actually proposed increasing the budget for the Animal Management Damage Board.)