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Chronic Wasting Disease

This information, "Chronic Wasting Disease - A Threat to Manitoba's Wildlife" (208kb), is available online as a PDF document.  A French version (142kb) is also available.

Chronic wasting disease (CWD) is a fatal disease of the central nervous system of deer and elk. This disease belongs to a group of diseases called transmissible spongiform encephalopathies (TSEs). TSEs tend to be species specific and most are not believed by scientists to be naturally transmissible between different species.

CWD has not been detected in Manitoba. To date, more than 2,300 deer and 1,400 elk have been tested and all have tested negative.

Besides CWD, other animal TSEs include:

  • scrapie of domestic sheep;
  • bovine spongiform encephalopathy (BSE) or mad cow disease in cattle; and
  • Creutzfeldt-Jakob Disease (CJD), a human disease found worldwide.

CWD is caused by an accumulation of abnormal proteins called prions, which causes degeneration of the brain cells. As the cells die, holes are created in the tissue, giving the brain a spongy-like appearance under a microscope. Once the disease has progressed, brain function is impaired with resulting changes in the animal’s behaviour.

Infected deer and elk show abnormal behaviour accompanied by progressive weight loss. In later stages of the disease, affected animals show signs of extreme weight loss, repetitive behaviour, drowsiness, lack of coordination, drooping head and ears, drooling, and increased drinking and urination.

Risks

There is no known case of a human being infected with CWD. Research suggests that this disease is not naturally transmissible to humans, pets or other domestic livestock.

The exact method of transmission has not been identified. Evidence suggests that the disease can pass from animal to animal by direct contact or through contamination of feed, soil, and water sources with saliva, urine and/or faeces from infected animals.

Currently, there is no approved live animal test for CWD. Diagnosis is made by microscopic examination of the brain and other tissues from dead animals.

Although progress has been made in understanding the disease, much is still unknown and active research is continuing. It is best to be cautious concerning which species can get CWD until there is conclusive information.

History

CWD has not been found in Manitoba, however, it has been detected in many areas of North America and in Korea. CWD was first identified in the late 1960’s in captive deer research herds in Colorado and Wyoming. In the early 1980’s, it was detected in free-ranging deer and elk in northeastern Colorado and southeastern Wyoming. It has since been found in farmed deer or elk herds in Saskatchewan, Alberta, Colorado, Wyoming, Montana, Kansas, Nebraska, South Dakota, New York, Minnesota, Oklahoma, Wisconsin, and Korea. CWD has also been detected in free-ranging deer or elk in Colorado, Wyoming, Illinois, Utah, New Mexico, Wisconsin, South Dakota, New York, Nebraska and Saskatchewan.

Consumption

The World Health Organization (WHO) has stated that, based on its review of the science, there is currently no evidence to indicate that CWD can affect humans. However, the WHO recommends that all products from animals known to be infected with any prion disease should not be consumed.

In Manitoba, harvested deer and elk are safe to consume. There is no evidence of CWD in Manitoba, the disease has not been detected in farmed elk, or wild deer or elk. Over 1,400 elk and 2,300 deer from the Riding Mountain and Duck Mountain areas and the southern part of the province have been tested for CWD - all tested negative.

Precautions

It is recommended that hunters follow the general precautions when field dressing an animal:

  • wear rubber gloves when field dressing carcasses;
  • minimize handling brain, eye, or spinal tissues;
  • debone the carcass, and avoid cutting through the spine;
  • thoroughly clean knives with soap and warm water; and
  • wash hands with soap and warm water.

If you observe an animal that appears to be sick, do not shoot the animal. Note the precise location and contact the nearest Manitoba Conservation and Water Stewardship office. Manitoba Conservation will collect and test any wild deer or elk that appears sick and is exhibiting signs of being infected with CWD. If you kill a deer or elk that is unhealthy and extremely thin do not field dress the animal. Attach the game tag and contact the nearest Manitoba Conservation and Water Stewardship office. Hunters who surrender a diseased or abnormal animal will be eligible for a replacement licence at no charge.

Manitoba Conservation is working cooperatively with other jurisdictions regarding the prevention, containment and eradication initiatives of chronic wasting disease.