By Ron VandenBoom
No evidence exists that CWD (chronic wasting disease) could infect cattle or sheep and there is no relationship between mad cow disease and CWD, said Dr. Elizabeth Williams, a researcher with the Wyoming State Veterinary Laboratory and the first person to characterize the disease in 1980. She is also the author of numerous scientific papers on the subject.
Williams said in a recent telephone interview that ongoing experiments being conducted in Wyoming indicate that no transfer of CWD to cattle or sheep is possible.
Cattle and sheep in the Wyoming experiment have been living together in close proximity for a long period of time with deer and elk that are believed to be infected, she said. "Results of the test have so far shown no transfer of the disease from one species to another."
The issue has gained importance in Montana in recent months due to efforts by the Montana Wildlife Federation and an off-shoot group known as MADCOW (Montanans Against the Domestication and Commercialization of Wildlife) to place an initiative on the November ballot that if approved by voters, would place a moratorium on new game farms in Montana and ban all existing shooting preserves. The initiative would also ban the transfer of game farm licenses prohibiting game farms from being sold or inherited by family members.
To make the November ballot MADCOW needs to collect 19,862 signatures, or five percent of 34 Montana districts.
Williams also made a definite distinction between CWD and the legendary "mad cow disease" that affected cattle in England several years ago.
"There is no relationship between mad cow disease and CWD," she said, while acknowledging that both disease are caused by what in medical terms is known as a spongiform encephalopathy.
Williams said that in laymans' terms, and to the best of their knowledge, CWD is caused by a "prion infectious agent" or a protein with an unusual shape that interacts with other healthy proteins.
The 100 percent fatal disease was first discovered in Montana elk on a game farm near Hardin that had came from a game farm near Philipsburg late last year.
The disease was first discovered in wild elk populations more than 30 years ago in Wyoming and Colorado and has since that time been detected in game farm animals in South Dakota, Oklahoma, Nebraska, and Saskatchewan, Canada, There is no test for the disease on a living animal and it can only be determined after the animal dies and its brain stem examined.
Williams said they are working on developing a test to detect CWD in living animals, but she would not speculate on how long that might take.
She also said they have determined that deer and elk can die from the disease in as little as 17 months based on observations of newborn animals that have died from the disease, but she could not say the same time period would apply to an adult elk or deer.
"We do not know what happens during the development of the disease," she said, adding that there hasn't yet been a lot of money put into research by either wildlife management agencies or universities because there are so many projects competing for available funds.
Williams did say she is hopeful a cure they will soon find a way to "interfere with the development of this disease," but said, she would "not hold her breath for a cure."
She noted that most of the information they have gathered regarding the disease and how it spreads has come from increased occurrences within captive herds. But she is quick to add that gathering data on what may be going on in wild populations is extremely difficult.
Williams said there is evidence that the disease could be transmitted through saliva, but why some animals become diseased and others also in contact do not leads some researchers to suspect a genetic link to the disease.
"In some prion diseases there has been a genetic link," she said, making them more susceptible. "But a genetic link has not been shown on elk."