Can Incinerators Solve the CWD Dilemma?

CWD is a fatal disease caused by mutated proteins, called prions, that attack an ungulate’s neurological system, causing certain death. It’s transmitted through the feces, saliva, blood, and urine of infected individuals, who can live for months or years with the disease before succumbing.

Wyoming’s deer and elk herds are some of the worst-hit in the country by the disease–deer populations especially. According to a state-wide 2021 report by the Wyoming Game & Fish Department (WGFD), CWD is present in 84% of the state’s mule deer herds. Some regions, like the west side of the Bighorns and the “Project Herd,” east of the Wind River Range, have 40% and 65% prevalence rates, respectively.

The spread has been slower in elk, but the CWD wave is still sweeping through the state’s herds, nonetheless.

The Jackson/Teton region was spared for a long time, but the first case was detected in December 2020 in a cow elk shot by a hunter in Grand Teton National Park (part of a unique cow harvest program that allows hunting in the Park).

“It was not a matter of if CWD would get here but when,” refuge Manager Frank Durbian told Mountain Journal shortly after the case was confirmed by WGFD.

In the two years since that first case was detected, numerous others have popped up in the mountains and plains surrounding the refuge, but shockingly none on the preserve itself. That doesn’t mean it’s not there, however. Nearly all testing occurs post-mortem (biologists remove lymph nodes and send them to a lab), making it difficult to detect the disease in live animals. And although infected individuals are usually gaunt, weak, and malnourished, the disease is not always that visible.

“It’s kind of scary because we're not sure where it’s going to stop,” Hank Edwards, supervisor of the WGFD Wildlife Health Laboratory, told Wyoming Public Radio last spring. “We don’t know where prevalence is going to level off.”

If CWD were to hit the refuge, it’s ripe for disaster. The refuge, managed by the US Fish and Wildlife Service, was established in 1912 to protect the Jackson herd as the town encroached on its winter range–the only low spot in a valley nearly surrounded by mountains. Now, over a century later, anywhere from 7,000 to 11,000 elk winter on the refuge, far above the management objective of 5,000 animals. And once on the winter ground, the elk tend to clump up into large herds, creating prime conditions for a disease to spread.

Inevitably, an average of 2% of the elk die on the refuge every winter. For the first time this winter, the refuge disposed of all carcasses with their new incinerator. Elk are dumped into a door on top of the machine using a forklift or tractor, and fall into an incineration chamber. The incinerator burns at 1,600 to 1,800 degrees Fahrenheit–hot enough to destroy CWD prions–and can cremate two elk carcasses in about an hour. The new disposal process is a huge improvement from burying carcasses in a pit, where CWD prions can remain viable for years.

Unfortunately for WGFD, the crematorium is only for use by the refuge. Wyoming was hoping to use the incinerator for road- or hunter-killed carcasses, but it appears unlikely they’ll be able to do so. Capacity doesn’t appear to be the issue. The incinerator can run up to 500 hours a year, meaning it can dispose of up to roughly 550 elk annually.

Rather, the transportation of carcasses and the potential for introducing CWD to the refuge are the main reasons for barring the state access. A key pillar of the refuge’s CWD response plan is to “prevent infected animals from contaminating CWD-free areas.” Bringing carcasses from elsewhere in Teton County or the state of Wyoming could inadvertently introduce disease to the refuge. It’s a prospect that would not only go against the refuge’s management plan but would also unnecessarily increase the risk of dispersing the disease further.

But if the incinerator does prove effective in controlling the spread of CWD on the refuge, could the method be used on a larger scale? The answer is complicated, and the main concerns of scalability are twofold: the expense may be prohibitive, and the issue of transporting infected carcasses goes beyond just the refuge. Let’s look at the state of Wyoming as a case study of the feasibility of implementing incineration on a state-wide level.

In terms of cost, $0.5 million is a drop in the bucket for the US Fish and Wildlife Service, which has an annual budget of around $3.5 billion but might be prohibitively expensive for WGFD. The department runs on an annual operating budget of around $81.3 million, with an additional $3.7 million for one-time projects (in 2022), such as research and wildlife overpasses. The huge cost of a single incinerator would likely mean the sacrifice of several conservation projects to pay for the machine, which would raise questions of priority. Ultimately, those decisions would have to be made by Wyoming taxpayers.

But more broadly, a single incinerator would not be practical for the entire state of Wyoming. Most western states, Wyoming included, actively discourage the transportation of whole game carcasses. CWD resides in spinal and brain tissues and is bound to end up wherever hunters dump contaminated carcasses–frequently in designated areas, but not always.

Legally, in Wyoming, if hunters choose to remove carcasses from the field, they are required to dispose of them in approved landfills. Currently, there are 37 landfills in Wyoming approved for disposal. Were the state to replace all those sites with incinerators, it would cost over $18 million. Alternatively, the state could choose to consolidate some of those sites, which would ultimately lead to hunters transporting contaminated carcasses longer distances, increasing the risk of further spreading CWD.

As this case study shows, implementing incineration on a state-wide scale to mitigate wildlife disease is a complicated issue. And while the refuge has the liberty of focusing management on its 24,000 acres, the same tactics might not be as practical on a larger scale (in the public sector, at least). The agriculture and ranching industries have used incinerators to dispose of carcasses (primarily poultry) for decades, but the economics driving those sectors are fundamentally different. To sum it up, the concept is practical, and will likely work on the refuge, but might not be a catch-all solution to containing CWD across all wild cervid populations.

Feature image via National Wildlife Refuge.