A mule deer buck on Garnet Hill Loop in Yellowstone National Park. (Neal Herbert/NPS)

Yellowstone National Park announced last week that a mule deer buck inside the park’s borders has tested positive for chronic wasting disease. The detection is a first for the park, which has previously managed to dodge the always-fatal disease despite its presence in the three states that neighbor Yellowstone.

In a Tuesday press release, the park said that the Wyoming Game and Fish Department tested the carcass of a radio-collared mule deer that died in the southeastern section of the park near Yellowstone Lake. The release notes that there’s “no effective strategy to eradicate [CWD] once it’s established” and its plan in the wake of the detection is to ramp up monitoring to determine how prevalent the disease is within the park.

CWD causes physiological and behavioral changes in infected cervids and ultimately leads to emaciation and death. It’s a transmissible, progressive neurological disease similar to mad cow disease, which jumped the species barrier in the mid-1990s, leading to the deaths of 176 Britons who developed a variant form of Creutzfeldt-Jakob Disease, a slow-acting degenerative brain disorder.

CWD is most common in white-tail and mule deer, but it has also been detected in elk and moose. It can be transmitted via contact between animals and their bodily fluids and excretions. The proteins that cause the disease are persistent in the environment once established in an area. Animals with later stages of chronic wasting disease appear sickly and malnourished.

Montana has hosted CWD dating back to at least 2017. It’s particularly widespread in the Libby and Dillon areas. Montana Fish, Wildlife and Parks has ramped up its surveillance efforts and instituted hunts aimed specifically at reducing the density of deer in those areas and obtaining more information about its prevalence. Since its initial detection in Montana six years ago, 3% of all animals tested for CWD have come back positive, though it appears that percentage is inching upward. Of the 2,437 animals tested so far this year, 85 have tested positive, or 3.5%. 

In parts of Wyoming CWD has become so widespread that wildlife managers are concerned about population declines due to “extraordinarily high rates of CWD” in some regions of the state, central Wyoming in particular.

A screenshot taken on Nov. 17 of a Wyoming Game and Fish Department interactive map showing the presence of CWD in Wyoming was yet to show detection of the disease in Yellowstone National Park.

Although there is no known case of the disease being transmitted from cervids to humans, FWP and the federal Centers for Disease Control and Prevention advise hunters not to eat animals that test positive for CWD. FWP encourages hunters to collect samples from animals they’ve harvested and send them in for testing before consuming meat from their quarry.

As a result of the detection, Yellowstone National Park is updating its Chronic Wasting Disease Surveillance Plan with an estimated completion date of 2024. 

“Most wild animals in Yellowstone are healthy and thrive in their natural environment, but sometimes wildlife can get sick just like people,” according to the park’s release. 

Visitors who see sick or dead wildlife are encouraged to report the sighting to a park employee and avoid handling the animal.

This story was originally published by Montana Free Press at montanafreepress.org.

Amanda Eggert studied print journalism at the University of Montana. Prior to becoming a full-time journalist, Amanda spent four years working with the Forest Service as a wildland firefighter. After leaving...

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  1. With a decent number of free roaming predators in YNP (wolves and cougars) – which are not subject to the pressures of indiscriminate hunting and trapping – and CWD now being detected it there, it would be an excellent opportunity (and great research project) to see if the predators really do keep the prevalence of CWD in check and the percentage of affected cervids low. The common thought among conservation/wildlife biologists is that if we allow predators to roam and establish stable territories and populations, they have the unique ability to keep cervid diseases in check because of their tendency to prey on the weak and sickly. Outside the protected confines of YNP, it is not an easy question to answer because (1) hunters that take cervids routinely go after the healthiest and biggest animals (not the sick ones) and (2) predators are not protected from hunting pressures, so their affect on the prevalence of CWD and other cervid diseases cannot be accounted for.

    I’ve always wondered what was the prevalence of CWD and other cervid diseases BEFORE the fur-trapper-settler-colonial era wholesale slaughter of predators in the lower 48 states took place. While not having a Time Machine to go back and answer that question, my gut tells me that the high prevalence and rapid spread of CWD and other cervid diseases is due to our removing predators from the land. Studying this question in the protected confines of YNP could provide us with a more definitive answer.

    1. One data point for you. Way back in 19096-97 when wolves were first exiting Yellowstone Park and began roaming the surrounding areas ( such as the Absaroka Front ) , a pack formed that ranged from Meeteetse south around the Owl Creek Mountains and west to almost Dubois. They named it the Washakie Pack because it spent much of its time in the Washakie Wilderness area.
      At the same time , CWD had just been detected in Mule deer in the southwest Big Horn Basin – Hot Springs County along Owl Creek- Cottonwood Creek. Two confirmed cases and Wyo GFD biologists suspected there were more in that area.( I don’t recall if a plausible source for where the deer had acquired the CWD was mentioned at the time. Maybe migrated in from the Big Horn mountains east of there ? ) . The Washakie wolves started ranging through that CWD hot zone. No more cases were reported after that. It went as quick as it came.
      The southwest Big Horn Basin is also home to a great number of Cougars , which were actively pursued by humans with snowmobiles and dogs. Except now Grey Wolves were in play.
      My working theory is either the Grey Wolves or the resident Cougars preyed on afflicted CWD deer…. the weak and slow are easier prey… and the spread of the disease was dampened. Based on the timing. Who could actually say ? No one at the time.

      A few years later there were meetings conducted by the trophy hunting managers of Wyo G&F for the forthcoming Grey Wolf trophy hunt seasons being planned for wolves outside of Yellowstone. At the packed Cody meeting , I directly asked the WyGFD meeting runner Bill Rudd about the Hot Springs CWD deer outbreak and disappeance at the same time as the wolves appeared there. I framed my question to ask if Wyoming Game & Fish saw the value of restoring an apex predator to the landscape so they clould do exactly that : manage ungulate herds using natural ecological methods instead of imposing artificial human hunting as the desired conservation tool.
      Rudd’s response said it all. He proclaimed that the Department saw absolutely no positive value for Grey Wolves roaming Wyoming outside Yellowstone whatsoever; that the Department believed wolves had been forcibly imposed on them by the Feds. He really said that… wolves are no good for wildlife management as they saw it . We can take that to mean because the wolves take away hunting opportunity for elk deer moose etc from us entitled human overlords, or something. Them wolves are eating our ungulates.
      I’m not so sure that attitude has evolved much in the past 20 years at WyoGFD. On the one hand they still don’t consider apex predators as being essential to effective actual wildlife conservation . On the other hand they was wolves, cougars, and bears as being a financial negative for big game animal harvesting by shorting the revenue from selling licenses that the Department sod esperately needs. The hunting license always came first. There is no money in supporting landscape scale ecology , to this day.
      Remember, it’s the Wyoming GAME and Fish Department , not the Wyoming Wildlife Department.