Frequently Asked Questions About Chronic Wasting Disease

What is "chronic wasting disease?"
Where is it found?
Where in Colorado is the Disease Found?
How often does it occur?
How is it transmitted?
Public Health Concerns
Is CWD transmissible to humans?
Is the disease transmissible to domestic livestock?
Does CWD affect antelope and/or bighorn sheep?
Can the animals be saved?
What precautions should hunters take when handling a deer or elk carcass?
What should a hunter do if they kill a deer or elk that appears unhealthy?
Why are hunters advised not to eat certain parts of deer and elk?
Detecting Chronic Wasting Disease
Other similar diseases
Ongoing research
Chronic Wasting Disease Management

What is "chronic wasting disease?"
Chronic wasting disease (CWD) causes damage to portions of the brain of deer and elk. Animals affected with CWD show progressive loss of body condition, behavioral changes, excessive salivation, increased drinking and urination, depression and eventual death. Chronic wasting disease is always fatal for the afflicted animal.

Where is it found?
CWD was first diagnosed in a Colorado captive elk 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. CWD has been known to affect elk, mule deer, and white-tailed deer. In South Dakota, CWD was discovered in three private, captive elk herds during the winter of 1997-98. However, screening of free-roaming elk and deer by Game, Fish and Parks in the fall of 1998 and 1999 found no CWD.

Where in Colorado is the Disease Found?
In Colorado, chronic wasting disease is found in an area - called the endemic area - encompassed by 18 game management units. These units cover approximately 10,000 square miles, about 9.5 percent of Colorado's entire land mass. Infection rates in the endemic area vary between location, herds and species.

Chronic wasting disease is far less prevalent in elk than deer. Less than 1 percent of elk in the endemic area have been found to be infected. Historical infection rates in deer herds vary from less than 1 percent to a range from 3 percent to 15 percent. The chart below indicates specific infection rates in mule deer harvested by hunters by game management unit. Monitoring of game management units varies between years and location. The information presented is based on a running total of hunter-killed mule deer tested since 1996.

How often does it occur?
CWD is relatively rare. In Colorado, for example, fewer than 200 cases, mostly in mule deer, have been documented since 1981. In checking hunter-harvested animals, less than 6% of deer and 1% of elk in north-central and northeastern Colorado were found to have CWD. Similar surveillance in southeastern Wyoming also indicated that less than 7% of deer had CWD. Deer and elk checked outside these areas in Colorado and Wyoming did not have CWD.

How is it transmitted?
Neither the agent causing CWD or its mode of transmissions have been identified. Experimental and circumstantial evidence suggests infected deer and elk probably transmit the disease through animals-to-animal contact and/or contamination of feed or water sources with saliva, urine, and/or feces. 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 may compound the problem.

Public Health Concerns
Epidemiologists with Federal Centers for Disease Control and Prevention in Atlanta and epidemiologists at the Colorado Department of Public Health and Environment have studied chronic wasting disease and found no link between it and any neurological disease that affects humans.

Health officials, however, advise hunters not to consume meat from animals known to be infected with the disease. In addition, they suggest hunters take simple precautions (as listed BELOW) when field dressing deer or elk taken in areas where the disease is found.

Is CWD transmissible to humans?
According to experts and public health officials, there's no evidence that CWD can be naturally transmitted to humans, or to animals other than deer and elk. As a general precaution, however, it's a good idea for people to avoid contact with any wild animal that appears sick.

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 the United Kingdom.

Though there are similarities, there is no evidence suggesting either scrapie or BSE is caused by contact with wild deer or elk.

Does CWD affect antelope and/or bighorn sheep?
No, CWD does not appear to affect antelope or bighorn sheep. Elk are fairly close relatives of the mule deer and, confined with infected deer, occasionally developed chronic wasting disease. Whether they actually caught the disease from the deer is open to some question. Pronghorns, bighorn sheep, mouflon, and other more distantly related species didn't come down with the disease, even though they were often exposed to it. From Chris Madson article, Wyoming Game and Fish.

Can the animals be saved?
Veterinarians say nothing can be done to save deer and elk affected by chronic wasting disease. 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. Feeding could increase the likelihood of transmitting the disease to other deer or elk.

What precautions should hunters take when handling a deer or elk carcass?
Public health officials advise hunters to take the following precautions when pursuing or handling deer and elk in the endemic area:

• Do not shoot, handle or consume any animal that appears sick; contact the Division of Wildlife in Fort Collins at (970) 472-4300 if you see or harvest an animal that appears sick.
• 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 harvested animals. (Normal field dressing coupled with boning out a carcass will remove most, if not all, of these body parts. Cutting away all fatty tissue will remove remaining lymph nodes.)
• Avoid consuming the meat from any animal that tests positive for the disease.
• Request that your animal is processed individually, without meat from other animals being added to meat from your animal.

What should a hunter do if they kill a deer or elk that appears unhealthy?
Do not shoot, handle or consume any animal that appears sick; contact the Division of Wildlife in Fort Collins at (970) 472-4300 if you see or harvest an animal that appears sick.

Why are hunters advised not to eat certain parts of deer and elk?
While the agent that produces chronic wasting disease in deer and elk has not been positively identified, there is strong evidence to suggest that abnormally shaped proteins, call prions, are responsible. Research completed by the Division of Wildlife and other agencies indicated that the prions accumulated only in certain parts of infected animals - the brain, eyes, spinal cord, lymph nodes, tonsils and spleen. Research also indicated that prions do not accumulate in muscle tissue. Based upon these findings, hunters are recommended to bone out their meat and consume only muscle tissue from animals harvested in endemic units.

Detecting Chronic Wasting Disease
Several opportunities exist during big game seasons for hunters to learn if their animals are infected with chronic wasting disease.

As part of its ongoing monitoring program, the Division of Wildlife will sample deer in certain game management units to track disease prevalence and trends. The monitoring program is designed as a continuing scientific study and not a meat inspection service. However, hunters who participate in the program by submitting heads of harvested deer for testing will be notified if their animal is infected with chronic wasting disease.

Participation in the Division of Wildlife's monitoring program in voluntary. Hunters in selected units will be notified by mail prior to the hunting seasons with details on participation and drop-off sites in their hunting area. Ten weeks or more may be required to complete testing before a hunter is notified of results.
Hunters pursuing game in units not included in the Division's monitoring program can have their animals tested by either the Colorado State University Diagnostic Laboratory or the Wyoming State Veterinary Laboratory. Contact either laboratory directly for testing details and fee information:

• Colorado State University Diagnostic Lab (970) 491-1281
• Wyoming State Veterinary Lab (307) 742-6638

Hunters with deer or elk that test positive for chronic wasting disease - as indicated by these testing facilities - will be eligible for a license fee refund. Game processing fees and other incidental expenses are not eligible for refunds.

Since monitoring began in 1981, fewer than 500 animals have tested positive for chronic wasting disease in the entire endemic area.

Other Similar Diseases
Chronic wasting disease belongs to a family of diseases known as transmissible spongiform encephalopathis. Within this family of diseases, there are three predominant variants that affect animals: scrapie, which has been identified in sheep for more than 200 years: bovine spongiform encephalopathy in cattle (sometimes referred to as "Mad Cow Disease"); and chronic wasting disease in deer and elk. Within the family, there are also two main variants that affect humans: Creutzfeldt-Jakob Disease, which occurs naturally in about one out of every one million people: and New Variant Creutzfeldt-Jakob Disease, which has been linked to the large-scale outbreak of bovine spongiform encephalopathy in cattle herds in Great Britain. Through that outbreak and the fact that the British consumed nearly 750,000 infected cattle during a 10-year period, approximately 100 humans have died to date after contracting New Variant Creutzfeldt-Jakob Disease.

Ongoing Research
Division of Wildlife researchers and biologists are studying chronic wasting disease on numerous fronts - addressing wildlife health issues and assisting public health experts and scientists with their ongoing research. Division of Wildlife personnel's work and expertise on the subject is noted not only nationally, but internationally as well.

Staff researchers and biologists personally conduct studies on the disease, and also collaborate and provide funding for studies conducted by other agencies and states. Employees have been involved in the following chronic wasting disease work:

• The successful development of improved, more sensitive testing procedures to detect chronic wasting disease in deer and elk.
• An ongoing field study designed to measure the relationship between deer density and disease prevalence.
• Ongoing research to track the progression of the disease through a deer's body to better understand how the disease is transmitted and how it can be better diagnosed.
• Ongoing studies to determine if chronic wasting disease can be passed to bighorn sheep, mountain lions and other animals.
• Specific studies to determine the ability of chronic wasting disease to infect cattle.
• Epidemiological studies conducted by state and federal agencies to determine if a link between chronic wasting disease and human neurological disorders exists.
• Laboratory studies to assess the potential susceptibility of different animal species, including humans, to chronic wasting disease.
• Ongoing monitoring studies to determine geographic distribution and level of prevalence of chronic wasting disease in the state.
• Research into early detection methods to diagnose chronic wasting disease in live, healthy-appearing animals.
• Studies of deer movement patterns to determine if links between disease prevalence and deer movement exist.

In addition, Division of Wildlife's staff serve as a national clearing house on information and resources concerning chronic wasting disease research. Each year, staff members coordinate a national meeting of chronic wasting disease researchers to share information and collaborate on study findings.

Chronic Wasting Disease Management
The Division of Wildlife's disease management efforts are focused on:

• Preventing the disease from spreading beyond the endemic area by prohibiting the transport of deer or elk from the affected area into other areas of the state.
• Reducing disease prevalence by maintaining deer and elk populations in the endemic at or below 1999 levels; enforcing regulations pertaining to the illegal feeding of big game animals; and aggressively culling diseased animals in the endemic area
• Continuing research in conjuntion with other agencies and state to further the Division of Wildlife's knowledge to manage affected deer and elk herds.

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