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Doug Leier, Published November 15 2011

Leier: Getting to know chronic wasting disease

In the last two years, two North Dakota deer have tested positive for chronic wasting disease. These are the first two positive cases discovered in the state among thousands of deer tested over the last decade or so.

Here’s a closer look at CWD with some common questions and the best answers science has at this time.

What is chronic wasting disease?

Chronic wasting disease is a progressive, fatal disease of the nervous system of white-tailed deer, mule deer, elk and moose. It belongs to a family of diseases known as Transmissible Spongiform Encephalopathies, or prion diseases. Although CWD shares certain features with other TSEs, like bovine spongiform encephalopathy (mad cow disease), scrapie in sheep and goats, and Creutzfeldt-Jakob disease in humans, it is a distinct disease apparently affecting only deer, elk and moose. It causes damage to portions of the brain, creating holes in the brain cells and causing a sponge-like appearance.

What wildlife species are affected by CWD?

Five species of the deer family are known to be naturally susceptible to CWD: elk, mule deer, white-tailed deer, black-tailed deer and moose.

How Is CWD transmitted?

It is not known exactly how CWD is transmitted. Experimental and circumstantial evidence suggest infected deer and elk transmit the disease laterally (animal-to-animal). The agent may be passed in saliva, urine, and/or feces or possibly through contact with an infected facility. CWD and other wildlife diseases seem more likely to occur in areas where deer or elk are crowded or where they congregate at man-made feed and water stations.

How do you test for CWD?

The only sure and practical way to diagnose CWD is through microscopic examination of the brain stem or lymph nodes in the head. Testing for CWD is done by federally approved laboratories. There is no quick test that you or your meat processor can perform to determine if your animal has CWD.

Is CWD transmissible to humans?

The World Health Organization has reviewed available scientific information and concluded there is no evidence that CWD can be transmitted to humans. Researchers have found no link between the disease and any neurological disease that affects humans, including the human TSE disease, Creutzfeldt-Jakob Disease.

Between 1997 and 1998, three cases of sporadic CJD occurred in the U.S. in young adults. These individuals had consumed venison, which led to speculation about possible transmission of CWD from deer or elk to humans. However, review of the clinical records and pathological studies of all three cases by the U.S. Centers for Disease Control and Prevention in Atlanta, did not find a causal link to CWD.

There is no scientific evidence that CWD is transmissible through consumption of meat. The prions are known to accumulate in certain parts of the infected animal – brain, spinal cord, eyes, spleen, and lymph nodes. Consumption of these parts is not recommended.


Leier, a biologist for the North Dakota Game and Fish Department in West Fargo, can be reached at dleier@nd.gov

Leier’s blog can be found online

at www.areavoices.com