CWD Suspected in Dead Elk at Wyoming Feedground

Earlier this year, two elk tested positive for chronic wasting disease on the Dell Creek Feedground near Pinedale, Wyoming. Since then, the situation has escalated. In late February, Wyoming Game and Fish personnel discovered a deceased bull and cow elk on that same feedground.

Game and Fish biologists collected a sample from the bull that subsequently tested positive, Raegin Akhtar told Mountain Journal, however the cow carcass was too scavenged to obtain a sample for testing so it’s unclear if the cow had contracted CWD.

This brings the total number of CWD detections at the Dell Creek feedground to as many as four following the first detection on the Scab Creek feedground earlier this winter.

The arrival of CWD at feedgrounds represents a critical juncture for wildlife management in Wyoming. The concept of artificial feedgrounds, created over a century ago to prevent elk starvation as their habitat was developed, now concentrates high elk densities during winter months in the same areas year-after-year—likely accelerating disease transmission, wildlife experts say.

Unlike brucellosis, which is also present in elk on feedgrounds, CWD is always fatal to elk, deer and moose. The average elk lives on average 1.5-2.5 years after infection before succumbing, and infected animals can spread the disease for years before showing any symptoms.

"The one thing we know is based on the setup of feedgrounds we have now, the prevalence [of CWD] will increase faster than it would in a natural setting—it's just a matter of how fast," said Samantha Allen, state wildlife veterinarian for Wyoming.

The disease's reach is already extensive. Justin Binfet, deputy chief of wildlife for Wyoming Game and Fish, told Mountain Journal CWD has been detected in 22 of 34 defined elk herds statewide, and in 35 of 37 mule deer herds.

"CWD in and of itself remains one of the biggest concerns we have with managing wildlife populations, particularly deer, into the future,” Binfet said. “There are places throughout the state where prevalence in mule deer has gotten to the point where there are population impacts. We consider it to be an added source of mortality for deer."

Wildlife managers face a complex issue. Shutting down feedgrounds could push hungry elk onto private lands and potentially spread brucellosis to livestock. And continuing to operate them will likely accelerate CWD transmission, according to a recent U.S. Geological Survey study.

“CWD is one challenge on these feedgrounds,” Allen said. “We definitely do need to make some changes going forward, but we have to factor in other things like brucellosis. We’re not just dealing with one disease; we’re dealing with multiple, and with far-reaching implications.”

Binfet said the recent cases on Dell Creek Feedground are noteworthy. “This year marked the first time we’ve had CWD-positive elk found dead on feedgrounds,” he said. “It’s certainly not surprising; we’ve been expecting this and planning for it, but we simply don’t know what’s going to happen and that’s important to note.”

Aside from continuing to develop Feedground Action Management Plans, there are a few changes taking place given the increase in cases. Binfet said extra vigilance is critical. One course of action is re-engaging with elk feeders on feedgrounds and encouraging the privately contracted feeders to keep an eye out for sick looking elk. There’s also been a more robust response to euthanizing elk that display symptoms of the disease, which he said is challenging since it’s not always clear what an animal’s symptoms indicate.

Allen says elk on feedgrounds behave differently than elk in the wild because they’re densely gathering over longer periods of time and over consecutive years. Naturally, elk move around more than they might on feedgrounds, and multiple animals testing positive in one area is an indicator that transmission has been setting in for more than a year.

“As of right now we know what we know,” Allen said. “I'm kind of bracing myself to see what the next couple of months are going to show. The situation is further along than we thought.”

While the disease poses no known risk to livestock or humans, it’s potential impact on Wyoming’s elk populations — if anything can be learned from mule deer — could be devastating.

“When we talk about epidemiology curves, you don’t typically see that in CWD. It’s not a typical pathogen, it just keeps spreading,” Allen said. “It’s a straight line increasing. How fast it increases depends on so many things.”

CWD is caused by misfolded proteins called prions found in the central nervous system and peripheral nervous system. Research has shown, according to Binfet, that when infected tissue passes through the GI tract of an animal, like a predator eating a carcass, the majority of the prions are denatured.

“Right now, the potential for a predator to consume and then spread the disease is very low, it’s not considered a significant concern,” he said, adding that the agency is monitoring the situation. “There's an absolute species barrier to CWD. No other species outside the deer family have been known to be infected in the wild. There is no plan to stop feeding on feedgrounds altogether.”

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