Chronic Wasting Disease Do Not Eat
General Information: Description and Symptoms
  • Chronic Wasting Disease or CWD, is a progressive, degenerative disease of the brain affecting deer and elk (Cervidae) in North America.
  • CWD is similar to other nervous system diseases known as transmissible spongiform encephalopathies (TSE). These include scrapie in sheep, bovine spongiform encephalopathy (BSE) in cattle, and Creutzfeldt-Jakob disease (CJD) in humans. Although the exact cause of CWD is unknown, it is associated with the presence of an abnormal protein called a prion. There is no treatment or vaccine currently available for the disease.
  • There is currently no scientific evidence that CWD affects humans, but we must exercise caution since there is some evidence to suggest that BSE, or “mad cow disease”, can affect humans.
  • It is not clear how CWD is transmitted but, based on experience with the disease in captive deer, both animal to animal and mother to offspring transmission may be possible; however, the most likely means of transmission is between animals that are in close contact with each other. In addition, elk and mule deer became infected after being placed in paddocks that had previously housed infected cervids, even though there were no other cervids presently on the premises, leading to the assumption that the agent could survive in the environment and cause disease.
  • Symptoms of infected animals may include lack of coordination, separation from other animals in a herd, excess salivation, depression, unusual behavior, paralysis, weight loss, difficulty swallowing, increased thirst and urination, and pneumonia. Signs usually last for weeks to months before the animal dies; however, some animals may not show clinical signs except for an acute pneumonia. Animals are usually 3- to 4-years of age before clinical signs appear, but may be as young as 18 months or as old as 13 years. The disease is tentatively diagnosed based on clinical signs, and is confirmed by isolating abnormal prion proteins during postmortem examination of the brain stem or from samples of lymphoid tissue from the affected animal. Current research, however, suggests that biopsies of palatine tonsils or rectal lymphoid tissue could be used to determine the presence of prion proteins in live animals.
Distribution and Surveillance
Click on image to enlarge.
Distribution of Chronic Wasting Disease
Current distribution (2013) of chronic wasting disease in North American cervids. Map courtesy of the Chronic Wasting Disease Alliance (
  • CWD is an emerging disease. That is, the number and distribution of infected wild and captive cervids has been steadily increasing since its discovery in the late 1960s at a research facility holding captive deer in Colorado.
  • In addition to several US states, many Canadian provinces have initiated surveillance programs to monitor CWD in free-ranging cervids.
  • British Columbia initiated a CWD surveillance program of deer and elk in 2001. The program primarily focuses on random surveys of road kills and hunter-killed deer and elk. As of January 2014, CWD has not been detected in BC.
BC Assessment and Surveillance Program
BC Chronic Wasting Disease Surveillance BC Chronic Wasting Disease Risk Assessment
Please click on the above thumbnails to download information from the BC Ministry of the Environment CWD Surveillance Program.
Further Reading
Return to Manual Home Page Disease List - Body Region Affected Disease List - Causative Agent or Risk Factor Disease Surveillance Form Glossary Contact Information
Return to Manual Home Page Return to Disease List - Body Region Affected Return to Disease List - Causative Agent or Risk Factor Disease Surveillance Form Download Glossary Contact Information