NEWS RELEASE: Eliminating Chronic Wasting Disease: A Progress Report From The Domestic Elk Industry.
USDA CONSIDERS HERD CERTIFICATION PROGRAM FOR CWD-MONITORED ELK HERDS
North American elk breeders have again provided leadership to eliminate a disease threat to farmed elk herds.
In October, 1999, officials of the Animal Health Committee of the North American Elk Breeders Association proposed, and the U.S. Animal Health Association passed, a resolution asking the USDA to establish a herd certification program for domestic elk. According to committee chairman Steve Wolcott, Paonia, Colorado, the program, when approved, will allow every domestic elk herd in any state to enter a CWD surveillance program.
"Our experience with other disease eradication efforts," Wolcott said, "is that the market will quickly start to pay a premium for animals from certified herds and states will require certified status for animal movement, so surveillance will become widespread."
"When a similar approach was used with TB, infected herds were identified, cleaned up, and reduced in numbers until now, five years later, we are on the verge of eradication-except, of course, for the TB infecting wild white-tailed deer in Michigan, which are under the control of the state wildlife authorities," Wolcott said.
The North American Elk Breeders Association (NAEBA) represents the domestic elk industry in the United States and Canada. Elk are raised as livestock for medicine (from the antlers), meat, breeding stock and trophy bulls. There are over 150,000 domestic elk on over 3,000 farms and ranches in North America. "The NAEBA membership is vitally interested in the eradication of communicable diseases in elk and is eager to work with state wildlife agencies in this effort," Wolcott affirmed.
SOME FACTS ABOUT CHRONIC WASTING DISEASE
Chronic Wasting Disease (CWD) is one of a family of diseases known as Transmissible Spongiform Encephalopathies (TSEs). This family includes scrapie in sheep and goats, BSE in cattle (also known as mad cow disease), Creutzfeldt-Jakob Disease in humans (CJD), as well as TSEs in cats, mink, squirrels, and other species.
TSEs are currently thought to be caused by abnormally shaped prions. (Normal prions are proteins that are found in all mammals.) Smaller than bacteria and viruses, the abnormal prions seem to convert normal prions to the abnormal form by contact, in a process that is not understood. CJD occurs in about one in a million people, apparently spontaneously and randomly. Scrapie has existed in domestic sheep in Europe for hundreds of years and in North America for 50 years, where it is widespread. It is not contagious to humans.
BSE emerged in cattle in the United Kingdom in 1986 and appears to have infected a handful of people. BSE has not been found in North America.
CWD was first observed in 1967 in a Colorado Division of Wildlife deer research herd. It may have started there or in the wild deer herds nearby, where animals were captured to stock the research facility. Infected animals may have been released into the wild. Deer that may have been infected were donated to the Denver zoo. Deer from the Denver zoo went to the Toronto zoo and to domestic elk herd(s) in the Dakotas and possibly other states. Although not proven, this seems to be the most likely route of CWD into domestic elk.
CWD typically appears at a very low rate, less than 1% of animals in a herd, unless it has gone undetected for many years. It does not seem to transmit outside of the deer family and has never been seen in humans.
THE RESPONSE OF THE DOMESTIC ELK INDUSTRY
CWD was first identified in farmed elk in December of 1997. The control and eradication of this disease became a top priority of NAEBA. In August of 1998 NAEBA convened a symposium of CWD experts, researchers, state and federal veterinarians, and industry representatives. The task given this group was to recommend a plan to eliminate CWD in domestic elk. This plan was submitted to the U.S. Animal Health Association in October of 1998, where it was fine-tuned and adopted as an official recommendation: "A Model Program for the Surveillance, Control, and Eradication of CWD in Domestic Elk." This document is being used as a guide by state veterinarians as they formulate regulations. A number of states now have in place regulations including surveillance of domestic herds to find CWD if it is present. This involves testing the brains of any animals that die. If CWD is found, the herd is quarantined until the disease is eliminated or the herd is depopulated. The past movements of infected animals are traced so that other possibly infected herds can be examined.
This model control program is already showing results. Currently, 13 herds are under quarantine or have been depopulated because CWD has been found or exposed animals were purchased-eight in South Dakota; two in Nebraska; and one each in Oklahoma, Colorado, and Montana. Most of these herds have had only one or two infected animals. These states and others have been looking for CWD in every farmed elk herd. Every domestic elk that dies for any reason is tested for CWD. After two years of intense surveillance, it appears that CWD is a rare disease in farmed elk. NAEBA, representing the domestic elk industry, intends to continue its efforts, based on the best available science and the experience of other livestock disease eradication programs, until CWD is eliminated from domestic elk.
Achieving the goal of eradication will become easier as more is learned about CWD. Quite a bit of research, about CWD and other TSEs, is being done. For instance, studies have suggested that CWD is not contagious to humans or cattle. Experiments at the national ARS lab in Ames, Iowa, have shown that CWD is not the same as BSE or scrapie.
Observations at the Colorado Division of Wildlife research station show the following: The typical incubation period is 20-24 months and elk are infectious only when they are showing symptoms, typically a couple of months before death. Transmission from animal to animal is probably through ingestion of saliva, mucous, feces, and/or urine. Removing for a couple of years all suspect elk from the herd when their symptoms first appeared seems to have eliminated CWD from the Division of Wildlife research herd. This herd, after being infected with CWD for over 20 years, has not had a CWD case for the past five years.
The most helpful development for eradication would be a live animal test. Several labs are working on different tests, and at least one is reporting encouraging results. The Elk Research Council, which is funded by NAEBA members, has spent $180,000 supporting research on CWD. The ERC is maintaining an infected herd (double fenced) in South Dakota in order to verify the efficacy of these experimental tests. Animals which have been depopulated from exposed herds have autopsies performed to collect tissues to support the ongoing work in developing a live animal test and understanding the pathology of CWD.
THE STUMBLING BLOCK
NAEBA fully expects to pursue the elimination of CWD in domestic elk until this goal is achieved. Groups like the Montana Wildlife Federation will continue to claim the sky is falling, just like they did five years ago with TB. But the biggest obstacle to total eradication will be the existence of CWD in wild deer and elk, currently confined to a swath of south-central Wyoming and north-central Colorado.
Twenty years after wild deer herds were known to be infected with a TSE, it is still not the stated goal of the state wildlife officials to eliminate CWD. No actions to reduce or eradicate CWD have been taken. Their own computer models show that if nothing is done, CWD will spread in the wild.
According to Wolcott, "The farmed elk industry, through NAEBA and the ERC, is taking responsibility for CWD in our domesticated animals and will achieve eradication if we are allowed. This will be costly, but it is the right thing to do. Unfortunately, we expect, in the end, to be faced with a situation like we now have with brucellosis in Yellowstone. After farmers and ranchers spent millions of dollars and years of sacrifice to eliminate a disease, they are faced with the threat of re-infection from wildlife whose managers refuse to act responsibly to control the same disease."