It was a tough start to the day during the Friday session of the Wyoming Game and Fish Commission meeting at the Cody Region offices.

The commission meets once a year in Park County, giving locals a chance to interact with those who lead the Game and Fish Department through good times and bad. Unfortunately, some news can sour even the most friendly events.

"I don't know who puts these agendas together, but we're starting with fish disease. Then we're moving right into CWD. And we're going to top it off at [the] brucellosis feed ground, so it should be a pretty light morning," quipped Corey Class, Cody Region Wildlife Management Coordinator.

Class and the entire commission understands Chronic Wasting Disease is a lot of things, but the one thing it is not, is funny.

Everywhere the department looks, they find the disease. New positive tests for CWD in deer, elk and moose are announced each year. There is currently at least one mule deer herd in the Cowboy State with nearly 70% prevalence to the always fatal neurodegenerative disease. Yet, until the final days of the disease, infected animals look generally healthy.

The facts are not pretty. On average, one of every five mule deer and one out of every four white-tailed deer in Wyoming are positive for CWD. The mood in the lightly attended public meeting turned deadly serious as Class shared the always disturbing news.

'So if we have 20% prevalence, we have about 10% succumbing to the disease annually," Class said.

According to the department's guide on mule deer, Wyoming’s mule deer are not only a cherished part of our wildlife heritage but also play a crucial role in our ecosystem and rural economies. Historically, mule deer were relatively uncommon in the early 1900s. Due to favorable conditions, populations surged in the 1950s and 1960s and reached historic highs. The most recent population peak occurred in 1991, with around 578,000 mule deer in the state. However, by 2023, the population has declined to an estimated 216,000 animals. Sharp declines in mule deer have occurred throughout western North America, most notably due to habitat loss and degradation along with changing weather patterns.

CWD plays a big part in declines

With the current population of mule deer, more than 20,000 deer (the majority being bucks) die each year from the disease. Every week the department is called to euthanize several deer in their end-of-life stage, Class said.

"When they get to what we call circling the drain — that last four to eight weeks of life — that's kind of what folks are used to seeing in the photos, right? The drooling, the head down, ears down," he said, pointing out the toll it takes on employees in the field.

"We deal with it a lot. It's a multi-weekly call here in Cody where we have to go put down animals that are showing these very symptoms. It's not a fun thing. It hits you every time ... the weight loss, drooling, behavioral changes. They're not moving around a ton. They're not doing what they're used to doing," he said, adding that in many cases, by the time the department gets the call, they can walk right up to the deer and euthanize it without much effort.

The disease hits deer everywhere in the state, but is considered serious in the local area. The Shoshone River herd in the Cody region ranks second in the state for CWD prevalence at just under 50%, behind the Project herd in the Lander region at nearly 70%.

Hidden foreign invader

The disease is caused by some pretty nasty prions, rather than bacteria or a virus in the case of most diseases. Prions are misfolded proteins not recognized by the body as a foreign invader, so the cervids' (including white-tailed deer, mule deer, elk, moose, red deer, roe deer and fallow deer) immune systems can't handle them. The disease can easily be passed by those in a herd living in close quarters through contact and bodily fluids, including fighting, socializing, maternal transfer, consuming infected plants, contact with infectious tissue and body fluid.

But possibly even more concerning, infected animals shed CWD prions into the environment through saliva, urine, feces, blood, semen, antler velvet and nasal mucus. This shedding can occur during the long preclinical (asymptomatic) phase — which often lasts 18 months to two years — meaning animals can spread CWD while still appearing completely healthy.

Studies and field observations show that CWD prions remain infectious in soil and water for at least two years to over 15 years, and in some cases can persist on the landscape for decades. Class said killing prions is not simply a matter of cooking the meat a bit longer.

"When we sit at the check station, folks will go, "Ah, I'm not really worried about it. I'll just cook it out." Well, we're talking incinerator type temperatures to take care of a prion. We're talking 40% bleach for five minutes," he said. "That's one of the biggest things with this disease. It separates it from a lot of others. It can remain in the environment for a long period of time in the soil, which can be taken up into the plants and everything else."

Bucks vs. does

Prevalence for the disease is higher in bucks than does. Class said the disease usually hits the older deer first.

"[The disease is] normally higher in those prime age or older bucks, and that's just a function of they're on the landscape longer. They have more interactions, more ruts under their belt. The longer you're on the planet, the longer you interact with other deer, more likely you are to have CWD," he said.

However, as prevalence in these areas increases, it does shift to younger age class animals, he said.

"What we're seeing is when it does get into this environmental contamination, we start to see a lot of yearling bucks that start getting it."

Human concerns

There is no documented immunity or recovery, and all cervids are susceptible to the disease. There are human health risk concerns, however the risks are largely unknown, Class said.

"Laboratory studies have shown there's a significant species barrier. To our knowledge, that hasn't been broken, so the risk is low," he said.

But scientists can't say there's zero risk. Public health organizations advise hunters not to consume animals that are CWD positive.

The U.S. Centers for Disease Control and Prevention strongly suggests having all deer or elk tested for CWD before you eat the meat. If your deer is processed commercially, consider asking to have your animal be processed individually. This ensures you are only getting meat from your animal.

"If your animal tests positive for CWD, do not eat meat from that animal," the CDC strongly urges hunters.

Game and Fish response

Class said there are some good things on the horizon to test for the disease. The test known as RT-QuIC (a highly sensitive and specific diagnostic assay used to detect pathological prion proteins associated with human and animal prion diseases) is an environmental test, and it enables wildlife managers to test far more than individual animals.

"We're not testing tissue [with the test] necessarily, but you can test ground, you can test water, you can test various different things, plant material to see if it's present, and it'll say if it's present or absent. The problem is it's a really sensitive test, and it's not field ready," he said.

Game and Fish biologists also use surveillance methods to observe the movement and intensity of the disease. Monitoring the disease across the state, biologists are on a five-year rotation between herds.

"We try to do about one to two herds per year within the regions. Our goal is 200 samples," he said.

Unfortunately, the surveillance process can take up to three years to accomplish.

Last year Game and Fish employees sampled about 5,000 cervids. More than 21% tested positive. This year the department has upped their game with over 7,000 animals tested. Prevalence remains high and, sadly, is growing in elk and moose populations.

"Unfortunately, [prevalence] is continuously getting higher," Class said.

The effort of the department goes well beyond simply testing. There are multiple levels of decisions made with the disease in mind. That said, the department has had one goal since coming up with their CWD management plan — involve the public.

"Before we did any substantial CWD management within the state, we outlined within the plan that we have to obviously reach out and work with the public and have public buy-in to the best that we can," he said.