Frequently Asked Questions

Q. What is Chronic Wasting Disease (CWD)?

A. Chronic Wasting Disease (CWD) is a disease of the central nervous system that occurs in deer and elk. It belongs to the family of diseases known as transmissible spongiform encephalopathies (TSEs) or prion diseases. Though it shares certain features with other TSEs, like mad cow disease or scrapie in sheep, it is a distinct disease apparently affecting only deer and related species. CWD occurs in wild deer and elk primarily in northeastern Colorado, and adjacent parts of Wyoming and Nebraska. CWD has also been found on elk farms in Colorado, Kansas, Montana, Nebraska, Oklahoma, South Dakota, and Saskatchewan.

Q. Is CWD transmissible to humans?

A. In the U.S., CWD has been killing deer and elk since 1967. In spite of ongoing surveillance for similar disease syndromes in humans, there has never been an instance of people contracting a disease from butchering or eating meat from CWD-infected animals. A World Health Organization (WHO) panel of experts reviewed all the available information on CWD and concluded that there is no scientific evidence that the disease can infect humans. However, there is much that scientists still do not know about CWD, and one cannot state that transmission of CWD to humans is absolutely impossible. Correlations have been found between bovine spongiform encephalopathy (BSE or mad cow disease) and Creutzfeldt-Jakob Disease, the human version of spongiform encephalopathy; and, while CWD has not been found to infect cattle or people, the deadly experience with mad cow disease is driving urgent research on the question.

Q. Is it still safe to eat venison from deer that originate from states with known CWD-infected herds?

A. There is no scientific evidence that CWD is transmissible through consumption of meat from an infected animal. CWD has not been linked to any human variant of the disease in the way that mad cow disease is associated with a variant of Creutzfeldt-Jakob Disease. The prion that causes CWD accumulates only in certain parts of infected animals – the brain, eyes, spinal cord, lymph nodes, tonsils, and spleen – and, therefore, these tissues should not be eaten. Health officials additionally advise that no part of any animal with evidence of CWD should be consumed by humans or other animals.

Experts suggest that hunters take the following precautions when field dressing deer in areas where CWD is found:

• Wear rubber gloves when field dressing carcasses;
• Bone out the meat from your animal;
• Minimize the handling of brain and spinal tissues;
• Wash hands and instruments thoroughly after field dressing is completed;
• Avoid consuming brain, spinal cord, eyes, spleen, tonsils, and lymph nodes of harvested animals. (Normal field dressing coupled with boning out of a carcass will remove essentially all of these parts.); and
• Request that your animal is processed individually, without meat from other animals being added to meat from your animal.

Q. What are the signs of CWD in deer?

A. CWD attacks the brains of infected deer and elk, causing the animals to become emaciated, display abnormal behavior, lose bodily functions, and die. Signs identified in captive deer include excessive salivation, loss of appetite, progressive weight loss, excessive thirst and urination, listlessness, teeth grinding, holding the head in a lowered position, and drooping ears. Many of these signs can also be caused by other diseases known in Wisconsin deer, such as Cranial Abscessation Syndrome, a bacterial disease of the brain, or by malnutrition. CWD is a slowly progressive disease. Most animals do not show signs of the disease until they are 15 to 35 months old; some may be as old as 13 years.

Q. How is CWD transmitted?

A. The mode of transmission between deer is not completely understood. It is thought that the disease is passed from animals in close contact with one another, and perhaps from mother to offspring. The prion which causes the disease is an abnormal version of a protein that normally occurs in the animal’s cells. This protein is not easily killed by environmental factors, heat, or disinfection, so transmission from a contaminated environment may also be possible.

Q. What is a prion?

A. A prion is an abnormal protein without any genetic material and is believed to be the infectious agent of all transmissible spongiform encephalopathies (TSEs). Most commonly found in the central nervous system, the abnormal prion “infects” the host by promoting the conversion of normal cellular proteins into the abnormal form. After conversion, the nerve cells in the region die away and the holes and lesions left behind give the tissue a sponge-like appearance. The CWD agent is smaller than most viral particles and does not evoke any detectable immune response or inflammatory reaction in the host. Additionally, the infectious prion believed to cause CWD remains viable in the natural environment for years; to date, this virulent protein has only been destroyed by incineration at temperatures greater than 1,110 degrees or by a bleach bath.

Q. How is CWD diagnosed?

A. Brain samples are collected from hunter-harvested or other dead deer and are examined microscopically using special stains to identify the CWD prion. A research team in Colorado has recently developed the first live-animal test for CWD, based on the collection of tonsil samples for microscopic examination. This test seems to work well in deer, but not in elk.

Q. What are cervids?

A. Animals belonging to the family cervidae, which includes deer, elk, moose, caribou, reindeer, and related species and hybrids.

Q. What should I do if I observe or harvest a deer that I suspect might have CWD?

A. Call your local Department of Natural Resources or Department of Wildlife office right away and report your findings.

Q. Is CWD a risk for livestock?

A. There is no evidence that CWD can be transmitted under natural conditions to cattle.