CHEYENNE - The complexity and uniqueness of chronic wasting disease, a brain disease in some southeast Wyoming and northeast Colorado deer, has led to national reporting that is unnecessarily alarming to hunters, believes Dr. Tom Thorne, wildlife veterinarian and Services Division chief for the Wyoming Game and Fish Department.
Thorne cites recent coverage by CBS television news and Field & Stream magazine that distorted the possibility of a link between the disease and humans and may have instilled unnecessary fear in big game hunters.
“There currently is no evidence chronic wasting disease is a threat to human health,” said Thorne of the disease which is caused by a “prion” or abnormal protein.
Diseases caused by prions are collectively called transmissible spongiform encephalopathies. In addition to CWD the group includes bovine spongiform encephalopathy or mad cow disease of Europe, a sheep affliction called scrapie and Creutzfeldt-Jakob disease, a very rare human disease.
Thorne adds that some reporting of CWD inappropriately equates it with mad cow disease of Europe, by calling CWD “mad deer disease.”
“Although mad cow disease can be transmittable to humans, the symptoms it induces in cattle of erratic behavior that induced its name are entirely different than the symptoms of CWD in deer,” Thorne said. “Although both are caused by prions, they are different diseases.”
The name chronic wasting disease reflects the impacts it has on infected deer. In its final stages, the disease induces deteriorating body condition, excessive salivation, both increased thirst and urination and eventually death.
There has also been reporting that the deaths of relatively young Utah and Oklahoma men from Creutzfeldt-Jakob disease were possibly linked to CWD because the men were deer hunters, and because Creutzfeldt-Jakob disease typically occurs in older people.
“But, the Center for Disease Control and Prevention examined the cases and concluded these unfortunate cases of Creutzfeldt-Jakob disease were not connected with CWD,” Thorne said.
The U.S. Food and Drug Administration’s advisory panel on transmissible spongiform encephalopathies and a committee of the World Health Organization have both stated there currently is no evidence CWD is a human health threat.
“Both organizations stop short of saying it is absolutely conclusive beyond a shadow of a doubt that CWD cannot be transmitted to humans, and I wouldn’t say that either,” Thorne said. “The reason we can’t say that is that, for obvious reasons, experiments of purposely exposing humans to CWD-infected tissue cannot be conducted, nor would we want them to be conducted.”
Although CWD was first documented in free-ranging deer and elk in southeast Wyoming and northeast Colorado in the 1980s, it is likely the disease has been present at least 30 to 50 years, Thorne adds. During that time there has been no corresponding incidence of transmissible spongiform encephalopathy diseases in humans in the area.
He also challenged statements that CWD “is found across the West.” “Chronic wasting disease has only been found in free-ranging deer and elk in southeast Wyoming, northeast Colorado and one positive case in the very western portion of the Nebraska panhandle,” he said. “In the affected area of Wyoming and Colorado tests show only 4 to 5 percent of deer have the disease and the rate is much lower for elk.”
In research facilities antelope and bighorn sheep have been confined in the same pens with CWD afflicted deer and have not contracted the disease.
For those who hunt deer and elk in southeast Wyoming and are concerned about CWD, Thorne has the following common sense recommendations:
Don’t shoot any animal, deer or otherwise, that appears sick, regardless of the suspected cause.
Wear rubber gloves when field dressing any game.
Bone out the venison and do not eat or handle the brain, spinal cord, eyes, spleen or lymph nodes.