Chronic Wasting Disease FActs
What is "chronic wasting disease?"
Chronic wasting disease (CWD) is a fatal brain disease of deer, elk, and moose that is caused by an abnormal protein called a prion. Animals infected with CWD show progressive loss of weight and body condition, behavioral changes, excessive salivation, increased drinking and urination, depression, loss of muscle control and eventual death. Chronic wasting disease is always fatal for the afflicted animal. The disease can not be diagnosed by observation of physical symptoms because many big game diseases affect animals in similar ways.
Where is it found?
CWD was first described in a Colorado Division of Wildlife captive deer research facility in 1967 and a few years later in a similar Wyoming research facility. It was later discovered in some free-roaming animals near these facilities in Wyoming and Colorado. The disease has now been discovered in either wild or captive deer and/or elk in Nebraska, Kansas, Oklahoma, New Mexico, Montana, Minnesota, West Virginia, Virginia, North Dakota, Wisconsin, Illinois, Utah, New York, Michigan, Maryland, Texas, Missouri, Colorado, Wyoming, Saskatchewan and Alberta. Moose in Colorado and Wyoming also have been found with the disease. In South Dakota, CWD was discovered in seven private, captive elk herds during the winter of 1997-98 and in another private, captive elk herd in August of 2002. CWD was first found in free-roaming wildlife in a white-tailed deer in Fall River County during the 2001 big game hunting season. In South Dakota, CWD has only been detected in free-roaming wildlife in Lawrence, Pennington, Custer, and Fall River Counties and Wind Cave National Park.
FOR MORE INFORMATION:
South Dakota Game, Fish and Parks
4130 Adventure Trail
Rapid City, SD 57702
605.394.2391 or 605.394.6786
South Dakota Game, Fish and Parks Information Office
20641 SD Highway 1806
Ft. Pierre, SD 57532
South Dakota Animal Industry Board
411 South Fort Street
Pierre, SD 57501
How often does it occur?
Surveillance by hunter-harvest survey and testing of sickly deer and elk implies CWD is relatively rare in free-roaming cervids when the number of animals present is considered. Thus far, in South Dakota, fifteen years of surveillance and testing of wild deer and elk have shown 150 CWD positive deer and 66 CWD positive elk out of 24,630 deer and elk tested. Of the 216 positive animals, Wind Cave National Park has discovered 41 elk and 10 deer that tested positive. In the 2011-2012 sampling period, 43 animals (29 deer, 14 elk) were found that were infected with CWD.
How is it transmitted?
How the pathogenic prion is transmitted from diseased animals to healthy ones is believed to be through direct animal to animal contact and/or contamination of feed or water sources with saliva, urine, and/or feces. Numerous organizations and individual scientists across the United States and Canada are continuing to conduct detailed investigations in an effort to obtain a definitive answer to the route of transmission. Evidence shows that infected carcasses may serve as a source of infection. CWD seems more likely to occur in areas where deer or elk are crowded or where they congregate at man-made feed and water stations. Artificial feeding of deer and elk will likely compound the problem.
Is CWD transmissible to humans?
Public health officials and the Center for Disease Control in Atlanta, Georgia have found no link between CWD and any neurological disease in humans. There is also no scientific evidence that CWD can be naturally transmitted to humans, or to animals other than deer, elk, and moose. As a general precaution, however, it's a good idea for people to avoid contact with any wild animal that appears sick regardless of the cause of the illness. Research also shows that the disease has been detected in the muscle tissue of infected mule deer. However, there is still no evidence that humans can contract the disease and it is believed that there is human resistance to the disease.
Is the disease transmissible to domestic livestock?
According to experts, there's no evidence that CWD can be naturally transmitted to domestic livestock. Chronic wasting disease is similar in some respects to two known livestock diseases:
- Scrapie, which affects domestic sheep and goats worldwide and has been recognized for over 200 years; and
- Bovine Spongiform Encephalopathy (BSE), which is a more recent disease of cattle in Great Britain and Europe. BSE has been found in Canada, and in the United States.
Though there are similarities, there is no evidence suggesting either scrapie or BSE is caused by contact or close association with wild deer or elk.
What should you do if you see a deer or elk that looks sick, emaciated (thin) and disoriented?
Call GFP at 605.394.2391 (Rapid City) or 605.773.3381 (Pierre) or the Animal Industry Board at 605.773.3321 (Pierre). Arrangements will be made to investigate the report.
Can the animals be saved?
Veterinarians say that nothing can be done to save deer and elk affected by CWD. However, removing affected individuals may help prevent the spread of infection within a herd. Feeding affected animals may keep them alive a little longer, but will not change the ultimate outcome. In fact, feeding could increase the likelihood of transmitting the disease to other deer or elk.
Simple precautions for hunters.
There is no evidence CWD can be naturally transmitted to humans. Research to-date indicates the prions causing CWD accumulates mainly in the brain, eyes, spinal cord lymph nodes, tonsils, pancreas, and spleen. New research has shown that the prions causing CWD can accumulate in muscle tissue, but at relatively low levels and with no evidence of an increase risk to humans. Therefore, public health and GFP officials advise hunters to take a few simple precautions when handling/transporting deer or elk carcasses.
- Do not shoot, handle or consume any wild animal that appears sick.
- Wear rubber gloves when field dressing and processing animals.
- Minimize handling brain or spinal tissues/fluids, and wash hands afterward.
- Bone out carcasses or at least avoid consuming brain, spinal cord, eyes, spleen, and lymph nodes of harvested animals.
What should a hunter do if he kills a deer or elk that is unhealthy.
In the rare event that an emaciated, unhealthy looking deer or elk is killed, leave the animal where it has fallen and contact any GFP Wildlife Officer, the Rapid City GFP office at 605.394.2391 or the Pierre office at 605.773.3381. Be prepared to show the animal to a Game, Fish and Parks representative and provide information where you can be reached for follow up investigation if necessary.
The Animal Industry Board in Pierre may also be contacted at 605.773.3321.
What is being done about CWD in South Dakota?
Eliminating CWD is difficult, given the limited understanding of its cause and transmission and the lack of an effective vaccine or treatment.
The Animal Industry Board established specific requirements after CWD was first diagnosed in private, captive elk herds to prevent further introductions or recurrences in private, captive elk and deer herds. All captive herds that were infected or exposed have been depopulated, and a mandatory cervidae (deer and elk) CWD surveillance and control program for captive cervids has been implemented.
Joint management strategies for CWD have been, aimed at intensified surveillance to determine to what degree CWD occurs in free-roaming animals. GFP, in cooperation with South Dakota State University and Wind Cave National Park, tested hunter-harvested animals, vehicle killed animals, sick animals, and research animals starting in 1997. Emphasis has been placed on testing elk and deer from areas near previously quarantined CWD private elk herd sites, areas where CWD has been found in wild animals, and sick animals from anywhere in South Dakota.
Animals tested from 1997-2012 by GFP and Wind Cave National Park consisted of 5,646 elk, 5,977 mule deer and 13,005 white-tailed deer. Two hundred and sixteen animals (150 deer, 66 elk) tested positive for CWD during this time period.
Animals tested from July 1, 2011 to June 31, 2012 by GFP and Wind Cave National Park consisted of 197 elk, 242 mule deer, and 970 white-tailed deer, and 1 moose. Forty-three animals tested positive for CWD during this CWD surveillance period. Twenty-eight deer and 2 elk were found by South Dakota Game, Fish, and Parks that tested positive for CWD. Wind Cave National Park found 12 elk and 1 deer that tested positive for CWD.
As of June 30, 2012, a total of 24,630 wild deer and elk have been tested for CWD in South Dakota and 66 elk and 150 deer have been found to have the disease. All CWD detected to-date in free-roaming wildlife has been in southwestern South Dakota and includes Lawrence County, Pennington County, Fall River County, and Custer County and Wind Cave National Park. Sick deer from several areas of the state are being tested as part of our CWD Surveillance Program, and no CWD has been found in other areas in South Dakota.
South Dakota agencies, in cooperation with citizens of the state, will continue to keep a close watch for the disease and determine its distribution and prevalence. This program will incorporate testing of hunter-harvested deer and elk, as well as sick deer and elk that are found and reported to GFP. The AIB will continue its CWD control and monitoring program involving private, captive elk and deer herds.
Revised September 2012