Photo © USFWS

Chronic Wasting Disease (CWD)

What is CWD?

Chronic wasting disease (CWD) is a fatal brain disease of deer, elk, and moose that is caused by an abnormal protein called a prion. Animals infected with CWD show progressive loss of weight and body condition, behavioral changes, excessive salivation, increased drinking and urination, depression, loss of muscle control and eventual death. Chronic wasting disease is always fatal for the afflicted animal. The disease can not be diagnosed by observation of physical symptoms because many big game diseases affect animals in similar ways.

What is a cervid?

A cervid is a mammal of the family Cervidae, which includes white-tailed deer, mule deer and elk.

What is a prion?

A prion is defined as an abnormal form of cellular protein that is most commonly found in the central nervous system and in lymphoid tissue. The prion “infects” the host animal by promoting conversion of normal cellular protein to the abnormal form.

The CWD infectious agent is smaller than most viral particles and does not evoke any detectable immune response or inflammatory reaction in the host animal. Based on experience with other transmissible spongiform encephalopathies (TSEs), the CWD infectious agent is assumed to be resistant to enzymes and chemicals that normally break down proteins, as well as resistant to heat and normal disinfecting procedures.

What does this mean to the future of these wildlife populations in South Dakota?

Research in Wyoming and Colorado has shown that if prevalence of CWD gets to high levels, population may not be able to sustain themselves and hunting of these populations may have to cease in order to maintain desired population levels.