What is Chronic Wasting Disease?

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Minnesota Board of Animal Health Reportable Disease of the Month Header

December 2016

Chronic Wasting Disease graphic

What is it?  Chronic Wasting Disease (CWD) is a neurodegenerative disease affecting deer, elk and moose (members of the cervidae family) and is always fatal. Abnormally shaped infectious proteins called prions cause the disease and convert normal proteins into infectious ones, which eventually leads to the animal’s death. CWD was discovered in Colorado in the 1960’s and is found in the United States, Canada, and more recently, in Europe. It belongs to a group of diseases known as transmissible spongiform encephalopathies.

How is it transmitted?  The disease is believed to be spread from one animal to another through direct contact and/or environmental contamination. Infectious prions can be spread via saliva, feces, blood, urine, and other bodily fluids. CWD and other prion diseases are difficult to control because, unlike bacteria and viruses, prions are resistant to inactivation by heat, freezing, ultraviolet light, and chemical disinfectants. Prions are also resilient in many environments and can remain infectious for extended periods of time.

What are the signs in deer, elk and moose?  Because CWD is a slow and progressive disease, signs of infection may take a long time to appear. Typical signs include behavioral changes, lack of coordination, stumbling, tremors, drooling, and weight loss. These are not the only symptoms and are not necessarily specific to CWD. Animals exhibiting these clinical signs often die within months.

How is Chronic Wasting Disease diagnosed?  It is confirmed by testing tissue samples from a dead animal’s central nervous system and/or lymph nodes. Tests, like immunohistochemistry, work by detecting antigens (prions) in those tissues.

What is the treatment?  There is no treatment or vaccine for Chronic Wasting Disease. The disease is fatal for infected deer, elk or moose.

Is there a risk to people?  Although CWD is not known to affect humans, caution is advised. The Centers for Disease Control says to avoid eating meat from deer and elk that look sick or test positive for CWD.

How can it be prevented?  Preventing CWD starts with surveillance, monitoring and early detection. Farmed deer and elk, 12 months of age and older, must be tested for CWD if they die or are slaughtered. In Minnesota, tissue samples (brain stem) are tested at the University of Minnesota’s Veterinary Diagnostic Laboratory in St. Paul. Deer and elk farms are also annually inspected by the Board and producers are required to report all deer or elk deaths and when animals are moved into or out of the herd. In the event of a positive test result for CWD, the Board will quarantine the affected herd.