EVANSTON — A disease impacting large game animals has been receiving increased attention in recent months and has led to some people labeling the illness “zombie deer disease.” In fact, a Google search for that term returns more than 30,000 results.
Many of the 30,000 search results paint a bleak picture of looming catastrophe and possible extinction. Others minimize the issue and question the science surrounding the disease. So, what exactly is the unfortunately-nicknamed affliction and what does the future hold?
Although the zombie terminology is new, chronic wasting disease (CWD), the proper term for the disease impacting North American cervids — deer, elk and moose — was discovered decades ago and has been slowly progressing ever since. The disease is a transmissible spongiform encephalopathy — a type of neurogenerative disorder associated with prions, which are abnormally folded brain proteins. Perhaps the most famous type of prion disease is Creutzfeldt-Jakob Disease, commonly known as Mad Cow Disease.
Cervids in the final stages of CWD infection become thin, even emaciated, and can exhibit vacant stares, stumbling movements and drooling. These symptoms precipitated the “zombie” references. There is currently no cure for the disease and its course is always fatal. However, infected animals may not exhibit any symptoms at all, and may appear perfectly healthy for months or even years before entering the final stages of the disease.
According to the Centers for Disease Control and Prevention (CDC), CWD was first identified in captive deer populations in Colorado in the 1960s and in wild deer in the 1980s. The disease has now been identified in free-ranging deer, elk and moose populations in 24 states and in two Canadian provinces.
Scientists believe CWD is spread through bodily fluids, including saliva, blood, urine and feces, or animal carcasses, either through direct contact or indirect contact with environmental elements that have been contaminated with bodily waste products. Prions are difficult, if not impossible, to destroy and an environment contaminated with them may remain contaminated for years, if not indefinitely.
Because of this environmental contamination, animals in confinement have been shown to be at greater risk of the disease. The CDC notes that prevalence in captive deer populations can be as high as 80 percent, while in free-ranging animals rates are dramatically lower, although still significant. A Wyoming Game and Fish interactive map shows a five-year estimate of hunter-harvested deer with CWD at more than 20 percent in some areas of the state, particularly in southeast Wyoming.
Prevalence is lower in free-ranging elk and, to date, only one moose in Wyoming has tested positive for the disease. A map on the CDC website shows that CWD has been found in every county in Wyoming except Uinta. WG&F tracks the disease by hunt areas instead of by county and that map too shows wide distribution of the disease throughout the state.
Mark Zornes, WG&F Wildlife Management Coordinator for the Green River region, said to this point the only documented CWD in that region was in three deer removed from the city limits of Green River a number of years ago.
Wyoming Game and Fish State Wildlife Veterinarian Dr. Mary Wood said wildlife officials in the state, and throughout the country, are concerned about CWD and its increasing prevalence and negative impacts on wildlife populations. Wood said the long time frame involved with the slow-moving but progressive disease presents challenges.
“It’s taken decades to get where we are now,” she said. “The long time frame can lull people into a false sense of security when you don’t see the negative impacts for a very long time. We are now seeing measurable negative impacts to wildlife.”
That concern is widespread. On March 18, several environmental groups filed a lawsuit against the U.S. Fish and Wildlife Service over the artificial feeding of elk on the Jackson Hole National Elk Refuge based on concerns that thousands of elk gathered in unnaturally close proximity is an ecological disaster waiting to happen.
Critics argue that diseases, including CWD, are more likely to spread under such conditions that more closely resemble confinement than free range.
Surrounding states, including Montana, have also taken exception to not only the National Elk Refuge but the other elk feeding grounds operated by the state of Wyoming. Officials in Montana have asked Wyoming officials to stop the artificial feeding, pointing out that wild animals do not observe state borders and migrate from place to place, potentially infecting other herds.
There is concern especially about the Greater Yellowstone Ecosystem (GYE) and what would happen to world-renowned wildlife herds if CWD were to take hold. This concern escalated last fall after the discovery of CWD in a deer inside Grand Teton National Park.
Not only do critics take exception to the artificial feeding of wildlife, but also to Wyoming’s historically hostile attitude toward large predators, such as bears and wolves, that may play a role in containing the spread of disease through game herds by preying on the weak and sick.
There are also questions about the possibility of CWD infecting humans through the consumption of infected meat. Although there is no documented case of transmission of CWD to humans, there are some studies that suggest it may be possible. Therefore, the CDC and the World Health Organization both recommend that people do not eat meat from infected animals.
There are also precautions that can be taken for safe handling of wild game, including not harvesting animals that appear sick, wearing rubber or latex gloves when field dressing, boning out meat when butchering, minimizing the handling of brain and spinal cord tissues, washing hands and instruments after field dressing and considering quartering and freezing meat until after CWD testing results are available.
During hunting season, hunters can visit WG&F check stations or regional offices for testing, although the animal’s head and a portion of neck tissue are necessary for free testing. Instructions on how to collect a CWD sample for testing are available on the WG&F website in either pdf or video form.
The myriad concerns about CWD have led WG&F to develop a CWD public working group, for which it is currently soliciting membership applications. A press release states, “The working group. . . will develop recommendations to revise Game and Fish’s CWD management plan.”
Wood said there will also be public meetings regarding CWD held in communities throughout the state beginning in May and continuing throughout the year.
Wood said management of the elk feeding grounds will also be part of the statewide conversations. “It’s really easy to look from the outside in and say shut them down,” she said. “It’s also easy to say leave them open. But nothing is as simple as we might like.” Wood said the CWD issue impacts the entire state and beyond and management plans will have to be long-term.
“We have to have a long view and be forward thinking. What does this mean for the future?” She continued, “This didn’t happen overnight, and management won’t happen overnight, either. It took decades to get here. It could take decades to turn it around.”
Applications for the working group are available online at the Wyoming Game and Fish website and will be accepted until April 5. Individuals from all levels of government, agriculture, sportspeople, conservation groups, scientists, outfitters, the general public and more are welcome to apply.