CWD Sampling

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 captive or wild free-ranging deer and/or elk in Colorado, Wyoming, Montana, Utah, New Mexico, Texas, North Dakota, South Dakota, Nebraska, Iowa, Kansas, Oklahoma, Arkansas, Minnesota, Missouri, Wisconsin, Illinois, Michigan, West Virginia, Virginia, Pennsylvania, New York, Maryland, and Canadian provinces of Alberta and Saskatchewan.

The disease attacks the brains of affected 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 symptoms of other diseases. CWD is a slowly progressive disease; infected deer may not show signs of the disease for 18 or more months. In fact, 94% of the deer from Illinois that have tested positive for CWD have otherwise appeared healthy.

For many years CWD was known to occur only in a small area of northern Colorado and southern Wyoming. However, the distribution of the disease has expanded into a number of other states and Canadian provinces. In February 2002, CWD was discovered in wild deer in southern Wisconsin. In November 2002, Illinois confirmed that a CWD-infected deer had been found near Roscoe in Boone County, near the Wisconsin border. To date, CWD has been confirmed in 17 Illinois counties: Winnebago, Boone, McHenry, DeKalb, Ogle, LaSalle, Stephenson, Jo Daviess, Kane, Grundy, Kendall, Du Page, Lake, Will, Livingston, Kankakee and Carroll. In Illinois, the disease is most common in eastern Winnebago, northwest DeKalb, west and central McHenry, most of Boone County, northeast Kane, central LaSalle, west and central Kendall and Grundy, and in the southeast and southwest corners of Jo Daviess and Stephenson counties, respectively. If left unmanaged, CWD prevalence will likely increase and the disease will spread throughout the state. There is currently no treatment or vaccination for the disease.

Since the first case of CWD was discovered in Illinois, the Department of Natural Resources started a “targeted surveillance program” for CWD in wild deer which 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 firearm deer seasons, Illinois officials systematically sampled hunter-harvested deer from around the state for CWD testing. The Department of Natural Resources also initiated a focused winter sharpshooting program for CWD management. Results of these practices have determined the geographic distribution of CWD currently encompasses 17 Illinois counties, with the core areas being along the county line separating Winnebago and Boone counties, northwest DeKalb County, and in the southeast and southwest corners of Jo Daviess and Stephenson counties, respectively. Other “spark” areas of the disease have radiated from the core areas of the disease.

Research has shown that CWD may be transmitted by various means. The disease can be passed by direct contact among animals in a herd, and through contact with or ingestion of infected bodily fluids (saliva, blood, and urine) and feces. Prions from decomposing infected carcasses and bodily waste may remain in certain soils for many years and cannot be eradicated easily by environmental factors, heat or disinfection, so transmission by environmental contamination also may be possible. Thus, high deer population densities may create a favorable environment for disease transmission.

Lymph nodes are collected from various sources of deer and are examined with a microscope using a special stain to identify the CWD prion. These samples must be from freshly killed deer which makes time very critical. Testing for CWD is conducted by federally approved laboratories: there is no quick test that you or your meat processor can perform to ensure that your animal does not have CWD.

CWD has been known to occur in deer and elk in the United States for years. In spite of ongoing surveillance for similar disease syndromes in humans, there has never been an instance of people contracting the 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. Information on precautions for handling and processing deer can be found at the following Illinois Department of Agriculture Website.

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.)

Call your local IDNR District Wildlife Biologist office which can be found here, or the Springfield Wildlife Office at 217-782-6384. The IDNR will make every effort to collect samples from the suspect animal for CWD testing.

There is no evidence that CWD can be transmitted under natural conditions to cattle, sheep, or other conventional livestock.

Some new regulations have been implemented, and 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. The full text of the current rules that relate to hunting can be found within 17 Ill. Adm. Code Section 635.30 Importation of Animal Carcasses and Parts; Section 635.40 Feeding or Baiting of Wildlife; and Sections 675.10 – 675.70 Special White-Tailed Deer Season for CWD Control.

A task force comprised of key staff from the Departments of Natural Resources and Agriculture has developed and implemented 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. The Department of Natural Resources also continues to implement its sharpshooting program to acquire additional samples for surveillance testing and monitoring, remove as many sick individuals as possible, and reduce the herd within known CWD locations in an effort to prevent further spread of the disease. Through these efforts, we have maintained our CWD prevalence at 1-2% over the infected area, and are confident that we are reducing the rate of spread of the disease to new areas.