Chronic Wasting Disease (CWD)

Frequently Asked Questions
October 2014
Contact: Kristin Mansfield
(509) 892-1001
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, moose and elk. It is one form of transmissible spongiform encephalopathies (TSE), which are infectious diseases of humans and animals that are characterized by a deterioration of brain tissue. These diseases are progressive and always fatal. Other TSEs currently known to science include scrapie of domestic sheep and goats, bovine spongiform encephalopathy (BSE) of cattle, kuru of humans, and Creutzfeldt-Jacob disease of humans.

Has CWD been found in Washington wildlife?
No. WDFW has tested thousands of animals over the past 15 years, and to date, there have been no confirmed cases of CWD in Washington deer, moose or elk.

Where has CWD been found?
Chronic wasting disease was first identified in captive deer in Colorado in 1967 and has since been found in wild and/or captive deer, moose and elk in many other states.

The table below lists the year that CWD was first diagnosed in species in North America.

State/Province White-tailed Deer Mule Deer Elk Moose
Year in
Year in
Year in
Year in
Year in
Year in
Year in
Year in
Canada, Alberta 2002 2007   2005        
Canada, Saskatchewan       2000 1996 2008    
Colorado     1967 1985 2008* 1981   2005
Illinois   2002            
Iowa 2012 2014            
Kansas   2006            
Maryland   2011            
Michigan 2008              
Minnesota 2006 2011     2002; red deer 2012      
Missouri 2010 2011            
Nebraska 2001 2004   1999        
New Mexico       2002   2005    
New York 2005 2005            
North Dakota       2010        
Oklahoma         2002      
Pennsylvania 2012 2012            
South Dakota   2001     1997 2002    
Texas       2012        
Utah       2003        
Virginia   2010            
West Virginia   2005            
Wisconsin 2002 2002            
Wyoming     1979 1985       2008
* - CWD prions found in meat sold at farmers market, traced back to captive elk

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. During the 2001 and 2002 hunting seasons, CWD testing efforts were broadened to sample harvested deer and elk at hunter check stations and from road-kills. Between 2001 and 2012, over 5,000 deer, elk and moose were tested for CWD within Washington, with none testing positive for the disease. Extensive surveillance will no longer take place as of autumn 2012; however, WDFW will continue to conduct targeted surveillance of animals demonstrating clinical signs of CWD.

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 in 1993 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.

Washington also passed the Revised Codes of Washington (RCW 77.15.290 and 77.15.160), which makes it  illegal to transport specific species of fish, wildlife or certain parts of the animals.

On the federal level, the U. S. Department of Interior and the U. S. Department of Agriculture formed a joint committee to develop a unified federal plan for combating CWD. Specifically, federal officials established a herd certification program, , are tracking herds and mapping  CWD cases, are developing better diagnostic tests and continue research on how the disease.

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. To date, no practical CWD screening test is available for live animals, although research is underway elsewhere to develop one.

How is CWD transmitted?
CWD is transmitted in the wild via oral ingestion of infective prions. This can occur in deer, elk, and moose through mutual grooming or contamination of  soil, feed, or water with the saliva, urine, or feces of infected animals.  There is currently no evidence that CWD can be transmitted to humans, domestic livestock or wildlife other than deer, moose 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, moose 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 prions 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 is to report sick animals to the nearest WDFW office.