Chronic Wasting Disease

What is Chronic Wasting Disease?

Chronic wasting disease is a fatal neurological disease found in cervids (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 bovine spongiform encephalopathy (Mad Cow Disease) or scrapie in sheep, it is a distinct disease apparently affecting only deer and related species. CWD has been diagnosed in wild free-ranging deer and/or elk in Colorado, Wyoming, Nebraska, South Dakota, Wisconsin, and Saskatchewan. Most recently, CWD was detected in samples taken from a single wild deer in northern Illinois. CWD also has been found in farmed /captive cervids in Colorado, Kansas, Minnesota, Montana, Nebraska, Oklahoma, South Dakota, Alberta, Saskatchewan, and Wyoming.

What are the signs of CWD in deer?

The disease attacks the brains of infected animals, causing them to become emaciated, display abnormal behavior, lose coordination and eventually die. Signs of the disease 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. CWD is a slowly progressive disease; signs often are not seen until the animal is 18 months of age or older.

Why should I be concerned about it?

For many years CWD was known to occur only in a small area of northern Colorado and southern Wyoming. However, in the past few years the distribution of the disease has expanded into a number of other states, Canadian provinces, and even South Korea. In most cases the spread into new areas resulted from movements of captive animals. Following the fall 2001 deer harvest in Wisconsin, CWD was discovered in wild deer in southern Wisconsin, and its origin there is unknown. CWD was detected in November 2002 in samples taken from a wild deer in Winnebago County, Illinois. It is the first reported case of CWD in Illinois.

What do we know about CWD as it relates to the Illinois deer herd?

The first case of CWD discovered in Illinois was confirmed in early November 2002 from samples taken from a wild deer in Winnebago County in northern Illinois. Illinois has participated in a "targeted surveillance program" for CWD in wild deer for about five years since that approach was first proposed by the Southeastern Cooperative Wildlife Disease Study, a diagnostic and research service which investigates wildlife diseases. In this program, deer that exhibit symptoms that could be caused by CWD are submitted for testing by an approved laboratory. In addition, during the fall 2001 firearm deer season, Illinois officials systematically sampled hunter-harvested deer from around the state for CWD testing. That targeted surveillance effort has been expanded for the fall 2002 firearm deer season. More than 3,000 samples will be taken and tested from hunter-harvested deer in 36 counties statewide.

How is CWD transmitted?

The means of transmission between deer is not completely understood. It is thought that the disease can be passed between animals in a herd and also perhaps from mother to offspring. Unlike many other diseases, CWD is not an infection by a living organism (such as bacteria), but appears to be caused by an abnormal version of a protein that normally occurs in the animal's cells. This infectious protein particle is called a "prion." It is not easily eradicated by environmental factors, heat or disinfection, so transmission from a contaminated environment may also be possible.

How is CWD diagnosed?

Brain samples are collected from hunter-harvested or other deer and are examined with a microscope using a special stain to identify the CWD prion. At this time, no reliable test of live animals is in use, although researchers are experimenting with techniques that appear to have potential.

Is CWD transmissible to humans?

CWD has been known to occur in deer and elk in the United States for decades. 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 CWD can infect humans. However, there is much that scientists still do not know about CWD and we cannot state that transmission of CWD to humans is absolutely not possible.

Is it still safe to eat venison from Illinois deer?

There is no scientific evidence that CWD is transmissible through consumption of meat from an infected animal. CWD has not been linked to the human TSE disease, Creutzfeldt - Jakob Disease, in the way that bovine spongiform encephalopathy has been in Europe. The prion that causes CWD accumulates in certain parts of infected animals — the brain, eyes, spinal cord, lymph nodes, tonsils and spleen — and, therefore, these tissues should not be eaten. As a precaution, health officials advise that no part of any animal with evidence of CWD should be consumed by humans or other animals. There is no test that your meat processor can perform to ensure your animal does not have CWD. Experts suggest that hunters take simple, common-sense precautions when field dressing deer:

• 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 harvest animals. (Normal field dressing coupled with boning out of a carcass will remove essentially all of these parts.)

What should I do if I observe a deer that I suspect might have CWD?
Call the local IDNR office, the regional IDNR office, or the Springfield Wildlife Office at 217/782-6384. The DNR will make every effort to collect samples from the suspect animal for CWD testing.

Regional office phone numbers:

Region 1, Sterling, 815/625-2968
Region 2, Barlett, 815/675-2385
Region 3, Champaign, 217/278-5773
Region 4, Alton, 618/462-1181
Region 5, Benton, 618/435-8138

Is CWD a risk for Illinois' livestock?
There is no evidence that CWD can be transmitted under natural conditions to cattle, sheep, or other conventional livestock.

Are any changes being made in Illinois hunting/wildlife regulations as a result of this disease?
Some new regulations have been proposed, but are not yet finalized. Any further changes that go into effect will be publicly announced. Through emergency regulations, we have banned the feeding of deer, because diseases are more easily spread among animals when they become concentrated at feeding areas. This change does not apply to food plots or standing crops, but includes salt blocks that are not part of an active livestock operation, etc. We have also limited the parts of deer or elk that hunters can bring into Illinois after they harvest the animal in another state: hunters are allowed to bring antlers on a cleaned skull cap, boned-out meat,and hides. Since the prion that causes CWD tends to concentrate in some of the inedible parts of deer that are discarded after butchering, this is one added precaution that can be taken to prevent the spread of the disease from other states into Illinois.

What are we doing to prevent the spread of CWD in Illinois?

A task force, comprised of key staff from the Departments of Natural Resources and Agriculture is developing and implementing plans regarding surveillance of wild deer and captive herds, import and export of deer and elk, and a response to the discovery of chronic wasting disease in Illinois. Hunters are asked to participate in the surveillance effort by providing samples of harvested deer when requested and by alerting authorities when suspect animals are found.

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