Chronic Wasting Disease (CWD)

Agricultural Disaster Preparedness and Recovery November 04, 2011 Print Friendly and PDF

Chronic Wasting Disease (CWD), one of the transmissible spongiform encephalopathies, is a fatal disease of the central nervous system of wild and captive elk, mule deer, white-tailed deer and moose. It has been found in wild populations in Colorado, Wyoming, Nebraska, Illinois, Wisconsin, Utah, South Dakota, New Mexico, West Virginia and New York as well as Saskatchewan and Alberta, Canada. CWD has been found in captive herds in several more states.

The causative agent is believed to be a sub-viral protein able to commandeer the normal protein-production system of brain cells, causing sheets of abnormal prion proteins to be produced in the brain; a “spongy” brain and signs of brain degeneration result.

Signs of illness are seen in mature animals, not young animals, because it takes a while for brain damage and signs of illness to develop. These signs include changes in behavior, weight loss, incoordination, tremors, circling or other repetitive walking, weakness, drooling, gait abnormalities and increased drinking and urination. Affected animals eventually become unable to rise. Death is inevitable.

Diagnosis of the disease is made by finding evidence of the abnormal prion protein in the brain or the characteristic “spongy” changes by microscopic examination. The abnormal protein can also be found in tonsils and lymph nodes during early incubation in some species, but not reliably.

The disease may be spread from infected females to their offspring by contact with the placenta or birth fluids or to herdmates through infected saliva, blood and possibly feces. Contaminated pastures or feeding areas may be a continued source of infection. Interspecies transmission between deer and elk is suspected as well.

There is no evidence that CWD is a human health concern, but certain disease control steps should be taken by hunters, meat processors, taxidermists and others who work with species at risk of CWD:

  • Avoid contact with any animal that appears ill. Contact your state Fish and Game Department to report sick wildlife.
  • Wear waterproof gloves and eye protection when dressing game.
  • Do not use household knives or saws to process game.
  • De-bone meat with a knife but do not cut through the spinal column, skull or through bones.
  • Use a designated knife or saw to remove the head from the spinal column and do not use this instrument again until it has been thoroughly cleaned and disinfected.
  • Do not handle or consume brain, spinal tissues, eyes, lymph nodes, tonsils or spleen from any deer, elk or moose. Do not eat any part of an animal that appeared sick.
  • After thoroughly cleaning and scrubbing with soapy water, disinfect equipment and surfaces used during processing with a 1:1 solution of household bleach.
  • Wash your hands after processing the animal.
  • Dispose of all offal (hide, brain, bones, etc.) in a landfill.
  • Ask commercial processors to process your meat individually.

Resources

http://www.michigan.gov/emergingdiseases/0,1607,7-186-25806---,00.html

http://www.aphis.usda.gov/animal_health/animal_diseases/cwd/

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.