WDFW Fact Sheet on Chronic Wasting Disease


August 2009
Contact: Kristin Mansfield
(509) 892-9138
WDFW Public Affairs
(360) 902-2250

What is chronic wasting disease?
Chronic wasting disease (CWD) is a disease of the central nervous system found in deer and elk. It is one form of transmissible spongiform encephalopathy (TSE). TSEs are infectious diseases of humans and animals that are caused by a deterioration of brain tissue. These diseases are progressive and always fatal. Other TSEs currently known to science include scrapie in domestic sheep and goats, bovine spongiform encephalopathy (BSE) in cattle, kuru in humans, and Creutzfeldt-Jacob disease in humans.

Has CWD been found in Washington wildlife?
No. To date, there have been no confirmed cases of CWD in Washington deer or elk.

Where has CWD been found?
Chronic wasting disease was first identified in captive deer in Colorado in 1967 and since has been found in wild and/or captive deer and elk in parts of at least 14 other states (Montana, Wyoming, Colorado, New Mexico, South Dakota, Kansas, Nebraska, Oklahoma, Wisconsin, Illinois, Minnesota, Utah, New York, and West Virginia) and the Canadian provinces of Alberta and Saskatchewan.

Can humans or domestic animals become infected with CWD?
To date, there have been no confirmed cases of CWD being transmitted to humans or passed to domestic animals or livestock.

Is the Washington Department of Fish and Wildlife monitoring wildlife for CWD?
Yes. In 1995 WDFW began targeted CWD surveillance, meaning that samples were collected from deer and elk exhibiting clinical signs similar to those associated with CWD. None of those samples tested positive for CWD. During the 2001 and 2002 hunting seasons, CWD testing efforts were broadened to sample harvested deer and elk around the state at hunter check stations and from road-kills. Since 2001, over 5,000 deer and elk have been tested for CWD, and to date, none of the samples have tested positive. Plans call for continuing to test hunter-harvested animals in future hunting seasons, focusing on areas in the eastern part of the state.

What is being done to minimize the risk of CWD?
Washington is considered a low-risk state for CWD because it is not adjacent to areas where the disease is endemic, and because the state took action a decade ago to curtail game farming, including banning the importation of live deer, elk and other cervid species that are native to Washington. That rule [Washington Administrative Code (WAC) 232-12-064], enacted in 1993, was an important step in reducing the risk of introducing CWD or other diseases into wild animal populations in this state.

On the federal level, the U. S. Department of Interior and the U. S. Department of Agriculture have formed a joint committee to develop a unified federal plan for combating CWD. Specifically, federal officials are putting plans in place to increase tracking of herds and mapping of CWD cases, develop better diagnostic tests and continue research on how the disease spreads.

How are animals tested for CWD?
Tests to confirm CWD are done in the laboratory, using brain stem or lymph node tissue taken from dead animals. Therefore, the best sources for test subjects are hunter-harvested and road-killed deer and elk. WDFW personnel collect samples from harvested animals through hunter check stations, field patrols and meat locker checks. The success of testing efforts relies on the cooperation of hunters in allowing samples to be taken from their harvested animals. To date, no practical CWD screening test is available for live animals, although research is underway elsewhere to develop one.

How is CWD transmitted?
The mode of transmission is unknown at this time. It is suspected that the disease may be transmitted by animal-to-animal contact and/or contamination of feed or water with saliva, urine or feces from infected animals. There is currently no evidence that CWD can be transmitted to humans, domestic livestock or wildlife other than deer or elk.

What are the clinical signs of CWD?
Animals with CWD exhibit excessive weight loss, appear uncoordinated and lethargic with their heads down and ears drooping, salivate excessively, drink more water than usual and isolate themselves from other animals. Eventually the afflicted animals die.

Should hunters take precautions against CWD?
Chronic wasting disease has not been found in Washington, and there currently is no scientific evidence of CWD being transmitted from deer or elk to humans. However, hunters who wish to take additional precautions may choose to avoid consuming the brain, spinal cord, eyes, spleen, pancreas, or lymph nodes of harvested deer and elk, since the CWD prion accumulates in these tissues. As always, WDFW advises hunters to avoid harvesting any animal that appears sick or is behaving strangely, to wear rubber gloves while field dressing game, and to thoroughly wash hands and equipment after processing carcasses.

One important way hunters can assist in CWD monitoring here is to cooperate with disease-testing efforts at field check stations. In addition, if hunters notice deer or elk exhibiting signs compatible with CWD, they are asked to report their observations to the nearest WDFW office.