CHEYENNE — Chronic wasting disease has pretty much established itself in some mule deer herds around Thermopolis in recent years, the Wyoming Game and Fish Department’s latest surveillance efforts show.
Game and Fish commissioners on Friday adopted a new management plan that aims to slow the spread of the fatal brain disease to new endemic areas such as Thermopolis, officials said.
“We think this is a sensible, reasonable approach to managing this disease,” Game and Fish Deputy Director Gregg Arthur said.
Arthur said the plan will continue to focus on managing the disease rather than trying to eradicate it. He noted there are no plans for any kind of large reduction of deer or elk populations under the plan, particularly around agency-operated elk feedgrounds near Pinedale and Jackson, should the disease reach northwest Wyoming.
“The disease may not be eradicated or stopped (under the management plan), but maybe we can slow the spread of CWD,” Arthur told commissioners.
Chronic wasting is a communicable brain disease of the deer family caused by an abnormal protein or prion. The disease has proved 100 percent fatal to animals that contract it, but there is no evidence that it can infect humans.
The prevalence of the disease in free-ranging elk in Wyoming has ranged from 2 percent to 3 percent. But experts warn that the disease could occur at much higher rates among elk on feedgrounds in Sublette, Lincoln and Teton counties because feeding concentrates animals in artificially high numbers.
Originally, the state’s draft plan warned that “scientific research has indicated that the prevalence of CWD in captive elk can exceed 50 percent.” The 50 percent figure has been removed from the revised plan.
The revised plan also removes language from the original draft that the “possibility of much higher prevalence rates in feedground elk” could result in a reduction in elk numbers. The new version of the plan instead says that it is “unknown” what effect disease rates exceeding 2 to 3 percent would have on free-ranging elk numbers.
Franz Camenzind, executive director of the Jackson Hole Conservation Alliance, said the revised plan is disappointing because it doesn’t appear to take the risk of chronic wasting disease killing large numbers of elk on feedgrounds seriously. So far, the disease has not been detected on elk feedgrounds.
Conservationists support phasing out feedgrounds before chronic wasting turns up on them. But many hunters and ranchers want the elk feedgrounds to remain because they help elk survive the winter and keep the animals away from haystacks used to feed livestock.
Game and Fish has examined the lymph nodes from about 1,800 hunter-harvested deer and elk since the surveillance program began in 2002. The agency collected another 4,261 deer, elk and moose samples in the fall of 2005 for analysis.
Terry Kreeger, supervisor of Game and Fish’s veterinary research services, said of those samples, 93 animals tested positive for chronic wasting, including 75 mule deer, 12 white-tailed deer and six elk.
“Year after year, we’re managing to hit our surveillance target (of about 4,000 samples),” Kreeger told commissioners. “The 93 (positives) were much like last year.”
Kreeger said new cases were diagnosed in mule deer in three hunt areas (37, 120, 127) near Thermopolis during the fall surveillance, including two infected deer in hunt area 37 near the Big Horn River and one from the Wedding of the Waters area in hunt area 120. He said the agency decided to collect additional samples from hunt areas around Thermopolis after the positive results. The department collected 227 samples, seven which tested positive for the disease, representing about a 3 percent prevalence rate.
“We wanted to get a better handle on the exact prevalence … plus maybe extinguish it from the areas if we harvested the only infected animals,” Kreeger said.
But a 3 percent prevalence rate suggests that chronic wasting disease has existed in the Thermopolis area for several years and that the disease is probably well-established in the mule deer population, Kreeger said.
“It appears this is a well-established, endemic area, but it still remains a mystery why … because we don’t know how the disease is transmitted,” he said.
Kreeger noted there is a large concentration of mule deer in the area and with mutual feeding, “there’s lots of opportunity for disease transmission.”
Kreeger said a new infection near Newcastle was most likely an extension of the eastern Wyoming or southwestern South Dakota endemic area. He said positive samples were also found in deer hunt area 77 in south-central Wyoming and elk hunt area 8 near the Colorado border southeast of Saratoga.