CWD: State biologists warn of high prevalence in Park County to the fatal ungulate disease

Posted 3/23/23

Hunting areas around Powell are being hit hard by Chronic Wasting Disease, with prevalence for the disease hitting nearly half of all bucks. CWD is fatal to wildlife; infected animals usually succumb …

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CWD: State biologists warn of high prevalence in Park County to the fatal ungulate disease


Hunting areas around Powell are being hit hard by Chronic Wasting Disease, with prevalence for the disease hitting nearly half of all bucks. CWD is fatal to wildlife; infected animals usually succumb within two years of contracting the highly contagious disease.

Cody Region Wildlife Management Coordinator Corey Class recently shared the grim news about the fate of the Shoshone River herd in hunt areas 121 (west of Powell) and 122 (south and southwest of Powell).

“We’ve never known an animal to survive CWD. They all succumb to it,” he told a crowd at the department’s season setting meeting Monday night in Powell in the Yellowstone Building on the Northwest College Campus. “Typically deer succumb to it in about 18 months — we usually say somewhere between 18 and 24 months.”

The National Deer Association, which works to ensure the future of wild deer, wildlife habitat and hunting, said CWD in deer has emerged over the last 20 years as one of the most significant issues in deer hunting in modern times, with enormous biological, economic, political and cultural impacts.

“The fact that the disease is complex and difficult to manage has made it controversial and has caused much disagreement and debate in the hunting world,” the association claims.

Among wildlife biologists in the state, there is little disagreement about the impact to mule deer populations. The disease is increasing in prevalence and the solutions call for tough, potentially unpopular actions.

Wyoming Game and Fish Department wildlife biologist Tony Mong confirmed that the high prevalence was among harvested bucks in the hunt areas and excluded roadkill and targeted animals (those that appeared sick and euthanized), which usually have a higher rate of infection. He also shared news that fawn ratios have dropped about 13% in the past five years and buck ratios remain fairly high — which sounds like good news, but it’s not.

“When you talk to CWD management, right now there’s two things [wildlife managers] can do; decrease buck ratios and decrease the overall population so they’re not so tightly packed,” Mong said.  

The possible solution might limit future deer hunting opportunities. But there are other species to consider as the disease spreads. According to the Centers for Disease Control and Prevention, North American elk, red deer, mule deer, black-tailed deer, white-tailed deer, Sika deer, reindeer and moose are all at risk.

“It is often difficult to diagnose a deer, elk or moose with CWD based on these symptoms alone because many of CWD symptoms also occur with other diseases and malnutrition. CWD is always fatal,” the agency states in its official report.

Scientists think CWD spreads between animals through contact with contaminated body fluids and tissue or indirectly through exposure to CWD in the environment, such as in drinking water or food.

CWD is a progressive disease that affects the brain, spinal cord, and many other tissues of farmed and free-ranging wildlife. Fortunately, CWD does not appear to naturally infect cattle or other domesticated animals, the CDC reports.

The older a deer is, the more likely it is to have been exposed to the disease, Class said. But the department is now discovering younger deer are increasingly being found to be positive for the disease.

“One thing that we are starting to see in some of the high prevalence areas is we’re starting to see yearlings [test positive]. So prevalence has gone up in two years, which is a little more alarming,” Class said.

In 2022, a total of 6,701 Wyoming deer, elk, and moose samples were analyzed by the Wildlife Health Lab, with 826 of those samples testing positive for CWD. This includes all hunter harvested, targeted and roadkill animals. 

Statewide numbers do not accurately reflect prevalence in specific hunt areas, the department advised. And, as a way to help understand more about the movement and survival rates, Game and Fish officials recently collared more than 200 mule deer in Park County.

“It’s definitely the largest study that’s ever gone on in this area, but across the state as well,” Mong said.

Other Park County hunt areas have high rates of prevalence, including many hunt areas southwest of Cody. Rates can vary by hunt area, but rates of prevalence are above 10% in most area hunt areas and twice to three times as high for white-tailed deer in the same units. Hunt Area 113 in the Upper Shoshone River herd is currently running almost as high as those near Powell.

“If you look across the areas, we see that 113 is currently testing at a prevalence rate of about 43%. The rest of the areas have prevalence rates between 5% to 15%,” Mong said.

The hunt area is experiencing an increasing number of white-tailed deer, he said.

“We’re banging the CWD drum,” Mong said. “I’m hoping that it helps to kind of loosen some [access issues], and some of the relationships that [Powell game warden] Jordan [Winter] is building right now.”

Winter was previously the Cody Region access coordinator for the department and is an expert in the complexities of the issues.

There are many opportunities to have harvested deer tested for the disease, including at Northwest College where students and professors are testing free of charge in the biology department. Game and Fish biologists and game wardens also offer free testing as well as training for hunters who wish to collect their own samples for more convenient testing.

Last year, hunters had the option to not receive results from their tested wildlife. The CDC reports “to date, there is no strong evidence for the occurrence of CWD in people, and it is not known if people can get infected with CWD prions.”

Yet, they also warn if your animal tests positive for CWD, “do not eat meat from that animal.”

Wyoming cautions the testing program is not focused on ensuring meat quality and safety; rather, testing is conducted for wildlife management purposes. Game and Fish follows the Centers for Disease Control recommendations that animals that are obviously ill or test positive for CWD should not be consumed. In addition, they recommend hunters wear rubber or latex gloves when field dressing as a general precaution against all diseases.