Chronic Wasting Disease Quick Fact Sheet
AAZV/AZA June 2003
Chronic Wasting Disease (CWD) is a progressive, debilitating and invariably fatal disease of deer and elk.
· First recognized in 1967.
· Clinical signs include progressive weight loss, behavior changes, and listlessness.
· Classified as a transmissible spongiform encephalopathy (TSE) or "prion” disease.
Range: The disease has been found in greatest numbers among free-ranging deer and elk in north central Colorado and southeastern Wyoming.
· CWD cases have been found in free-ranging deer and/or elk in Nebraska, South Dakota, New Mexico, Utah, Illinois, and Wisconsin.
· CWD has been diagnosed in farmed elk and/or deer herds in several states including Colorado, Kansas, Minnesota, Montana, Nebraska, Oklahoma, South Dakota, and Wisconsin.
· CWD has been identified in both free-ranging deer and privately owned elk in Saskatchewan, and farmed elk in Alberta, Canada.
· CWD has been identified in farmed elk in Korea.
Species affected: CWD has affected mule deer, white-tailed deer, and elk. Other ruminants housed near infected cervids have not been infected. It is not known whether other cervid species (North American or exotic) are susceptible to infection.
Transmission: Transmission between animals is most likely to occur through animal-to-animal contact and/or contamination of feed or water sources with saliva, urine or feces from a diseased animal. The route of transmission has not been definitively determined. It does not appear that CWD is transmitted to other ruminant species in contact with infected cervids.
Diagnosis: Diagnosis is confirmed by immunohistochemical staining of the obex portion of the brainstem. Recently, two CWD diagnostic test kits have been approved by the USDA (Bio-Rad, VMRD). These ELISA based tests can be applied to lymph node or brainstem, and are licensed for use in deer and elk. Although these will be used for surveillance of free-ranging cervids, they are not currently approved for farmed cervid regulatory programs. Experimental tests using tonsil and lymph node are being investigated as potential antemortem diagnostics. See http://www.bah.state.mn.us/diseases/cwd/brain_removal.htm for instructions and diagrams.
Zoonotic Potential: Current information indicates that CWD does not cause illness in people.
The known prion diseases of humans and domestic animals appear to be caused by prions unrelated to CWD. It is unknown whether consumption of infected tissue may present a risk.
Prevention: Risk avoidance recommendations for those with close contact to susceptible animals (hunters, wildlife biologists, pathologists) include:
· Do not consume meat from any deer or elk that looks or acts sick.
· Wear gloves when field dressing/performing necropsy on carcasses and wash hands and instruments thoroughly when complete.
· Do not consume brain, spinal cord, eyes, spleen, tonsils, and lymph nodes from deer and elk.
Eradication: The USDA and some states have a voluntary herd-certified status program. A federal program for surveillance and eradication of CWD is being developed by the USDA.
Regulations: Several states have placed moratoria on imports of cervids at the time of this writing. Check with your State Veterinarian.
Recommendations for zoos:
· Obtain a herd history of source of captive elk or deer that may be acquired for the collection.
· Sources of captive elk or deer should ideally be from another AZA-accredited institution or herd that is certified as CWD-free.
· Minimize potential contact between collection and wild cervids.
· Submit brain for CWD surveillance (NVSL) from any cervid that dies or is euthanizedover the age of 12 months.
· Check with state veterinarian’s office regarding current restrictions in movement of cervids.
CWD information –
USDA - http://www.aphis.usda.gov/lpa.issues/cwd/cwd.html
State of WY - http://gf.state.wy.us/services/education/cwd/index.asp
State of CO - http://wildlife.state.co.us/cwd/index.asp
State of NE - http://www.ngpc.state.ne.us/wildlife/cwd/cwdinfo.html
State of WI – http://www.dnr.state.wi.us/org/land/wildlife/whealth/issues/cwd/
Congressional hearings on CWD – http://resourcescommittee.house.gov/107cong/forests/2002may16/agenda.htm
(See Mike Miller’s testimony for concise review of CWD)
Other TSE information –
Scrapie – www.aphis.usda.gov/vs/scrapie
BSE – www.aphis.usda.gov/lpa/issues/bse/bse.html
MAF UK – http://www.defra.gov.uk/animalh/bse