Chronic Wasting Disease

North Dakotans hunting in a state or province that has not identified CWD, or hunting in an area within a state or province not listed in the CWD proclamation, are asked to follow the guidelines listed below as recommendations to minimize any potential spread of disease.

 

There is no scientific evidence that CWD can be naturally transmitted to humans. However, as a general precaution, North Dakota Game and Fish and health officials advise that hunters take the following common sense precautions when handling and processing deer or elk in areas known to have CWD:

 

1. Avoid sick animals. Do not shoot, handle, or consume any animal that appears sick; contact your local wildlife agency personnel.
2. Wear rubber/latex gloves when field dressing carcasses.
3. Minimize handling the brain, spinal cord, eyes, spleen, tonsils and lymph nodes of any deer, moose or elk. 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.
4. Thoroughly wash hands, knives and other tools used to field dress the animal. Disinfect tools by soaking them in a solution of 50 percent unscented household bleach and 50 percent water for an hour. Allow them to air dry.
5. Avoid contact with any animal that appears sick and do not consume.
6. Bones and unprocessed remains should be disposed of through burial, landfill or incineration.

Chronic wasting disease (CWD) is a progressive, fatal disease of the nervous system of white-tailed deer, mule deer, elk and moose. It belongs to a family of diseases known as Transmissible Spongiform Encephalopathies (TSEs), or prion diseases. Although CWD shares certain features with other TSEs, like bovine spongiform encephalopathy (BSE or mad cow disease), scrapie in sheep and goats, and Creutzfeldt - Jakob disease (CJD) in humans, it is a distinct disease apparently affecting only deer, elk and moose. It causes damage to portions of the brain; creating holes in the brain cells and causing a sponge-like appearance.

 

The origin of CWD is unknown and it may never be possible to definitively determine how or when CWD arose. It was first diagnosed in a Colorado elk research facility in 1967 and a few years later in a similar Wyoming research facility. It was later discovered in wild elk and deer near those facilities in Colorado and Wyoming.

The known distribution of CWD in wild deer, elk, and moose includes Alabama, Arkansas, Colorado, Idaho, Illinois, Iowa, Kansas, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Mexico, New York, North Carolina, North Dakota, Ohio, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia, Wisconsin, Wyoming, Alberta, Manitoba, and Saskatchewan.

CWD also has been found in farmed elk or deer herds in Colorado, Illinois, Iowa, Kansas, Michigan, Minnesota, Missouri, Montana, Nebraska, New York, Ohio, Oklahoma, Pennsylvania, South Dakota, Texas, Utah, West Virginia, Wisconsin, Alberta, Quebec, Saskatchewan, and South Korea.

CWD has also been found in wild moose and reindeer in Scandinavia.

CWD was first detected in North Dakota in a mule deer buck taken in the fall of 2009 in the southwestern part of the state. See http://www.cwd-info.org for more information.

 

CWD has unfortunately become more prevalent in recent years. In Wisconsin, CWD infects about 25-30 percent of the deer in its core management zone. In other areas, percentages of infected animals range from 0-30 percent in deer and wild elk. The number of animals diagnosed with CWD has steadily increased in recent years. It has also been found in numerous new locations where the disease was not previously detected.

 

Most members of the cervid family are known to be naturally susceptible to CWD: elk, mule deer,  white-tailed deer and moose. Susceptibility of other members of the deer family (Cervidae) and other wildlife species is variable and depends on the nature of and route of exposure.

 

CWD is a slowly progressing disease; signs typically are not seen until the animal is 12-18 months of age and may take as long as 3 or more years. CWD attacks the brains of infected animals, causing them to become emaciated, display abnormal behavior, lose bodily functions, become weak and eventually die. Clinical signs identified include excessive salivation, loss of appetite, progressive weight loss, excessive thirst and urination, listlessness, teeth grinding, lowering of the head and drooping ears. It should be remembered that many of these signs can be a result of other diseases.

 

Prions have been found in bodily secretion such as feces, urine and saliva, and in tissues such as neurologic tissue (brain, spine peripheral nerves), lymphatic tissues, heart, spleen, kidney, lung, soft palate and skeletal muscle. Experimental and circumstantial evidence suggests infected cervids transmit the disease laterally (animal-to-animal). In wild populations, decomposition of carcasses, scrapes, rubs and shared feeding sites play a role in transmission as well as social behavior. CWD and other wildlife diseases seems more likely to occur in areas where deer, elk or moose are crowded or where they congregate at man-made feed and water stations. Artificial feeding of deer, elk and moose compounds the problem. Prions exist in the environment for years to decades. Recent research indicates that prions can be aerosolized and lead to infection also.

 

Post-infection prions can be detected in as early as a few months in lymphatic tissue. The prions progressively move from the lymphatic system into the neurologic system. Prions have been found in lymph nodes of infected wild fawns as young as 5 months old and in the obex (brainstem) at 9 months old. Clinical signs will not start to appear for 10-18 months post infection, but may not show up for years. Although clinical signs may not be outwardly apparent, prions are shed throughout the duration of the infection. Infected animals if not harvested or removed will eventually succumb to the disease.

 

CWD is caused by a prion, an abnormal form of cellular protein that is most commonly found in the central nervous system and in lymphoid tissue. The prions cause sponge-like lesions in the animal's brain. These abnormal prions tend to accumulate in certain parts of infected animals, i.e., brain, eyes, spinal cord, lymph nodes, tonsils and spleen. It is this accumulation that leads to eventual cell death, which leads to clinical signs. CWD is not caused by a virus, bacteria or nutritional imbalance.

 

The only sure and practical way to diagnose CWD is through microscopic examination of the brain stem or lymphatic tissues of a cervid using immunohistochemisrty (IHC). A more rapid test using ELISA on lymph nodes is reliable as a screening method for the disease. A test for live animals, involving the removal of tonsils or rectal lymphatic tissue is currently in experimental and research stages. Testing for CWD is done by federally-approved laboratories; there is no quick test that you or your meat processor can perform to determine if your animal has CWD.

 

There is currently no effective treatment or vaccine for a cervid that has CWD. An animal displaying clinical signs consistent with CWD should be euthanized. Removing infected animals will help prevent spread of disease or infection.

 

Currently there are conflicting experimental studies regarding the potential for CWD to infect people. Researchers have found no naturally occurring link between the disease and any neurological disease that affects humans including the human TSE disease, Creutzfeldt-Jakob Disease. Between 1997 and 1998, three cases of sporadic CJD occurred in the U.S. in young adults. These individuals had consumed venison, which led to speculation about possible transmission of CWD from deer or elk to humans. However, review of the clinical records and pathological studies of all three cases by the Centers for Disease Control and Prevention in Atlanta, did not find a causal link to CWD.

 

The prions are known to accumulate in certain parts of the infected animal -- brain, spinal cord, eyes, spleen, meat and lymph nodes. Consumption of these parts is not recommended. Furthermore, health officials advise caution. Hunters are encouraged not to consume meat from animals known to be infected. Hunters should take common sense precautions when field dressing and processing deer or elk taken in areas where CWD has been diagnosed.

There is no evidence that CWD can be naturally transmitted to livestock or animals other than deer and elk. Numerous experiments and investigations are currently being conducted.

 

Note the location and as much information as possible about the animal and situation. Call the North Dakota Game and Fish Department at 701-328-6300 immediately. Arrangements will be made to investigate the report.

 

The North Dakota Board of Animal Health initiated mandatory inventory of all game farms in 1993 and mandatory CWD surveillance, reporting and testing in 1998 of any farmed elk or deer of more than 12 months of age that dies from any cause. In September 2017, after nearly 20 years of mandatory testing with no positive farmed animals identified, the Board of Animal Health voted to make testing voluntary for some producers. Producers who ship animals across state lines must continue to test. Producers who are located within 25 miles of a CWD positive wild deer must continue to test. The North Dakota Game and Fish Department takes the risk of CWD very seriously. The Game and Fish Department will continue to work with the farmed deer and elk producers, as well as the BOAH, to minimize the risk of CWD to both wild cervids and farmed deer and elk. Before any farmed deer or elk can be imported into the state, it must pass a five-year herd health risk assessment, which includes a review of the herd history approved by the BOAH. If approved, animals must meet other requirements before importation, including veterinary inspection for general health and tuberculosis and brucellosis testing.

 

Note: See current CWD proclamation for restrictions.

Game and Fish would prefer that you take the tagged head with you out of the field and bring it to one of the drop-off stations in the unit so it could be tested.

If that’s not convenient, tag the deer as required, then take two photographs using a cellphone with location, date and time stamp turned on. Take one photograph of the entire animal at the kill site with tag attached, and a second photograph of a closeup of the tag so that the tag information is readable. If a hunter leaves the head in the field at the kill site, after taking photos and saving them, the ear or antler with the tag attached must be cut off and accompany the meat or carcass while in transport. The photographs of the tagged deer must be shown to any game warden or other law enforcement officer upon request.

Not all prion diseases are the same- some are inherited, some arise spontaneously, and some are transmissible between individuals. The prion that causes CWD is transmitted from animal to animal. Numerous, good scientific studies have established this. The CWD prion can be spread from infected to non-infected animals through direct contact or through contamination of shared resources or environments. Some of the dozens of research studies include:

• Miller MW et al. 2004. Environmental sources of prion transmission in mule deer. Emerging Infectious Diseases. 10:1003-1006.
• Mathiason CK et al. 2009. Infectious prions in pre-clinical deer and transmission of chronic wasting disease solely by environmental exposure. PLoS ONE 4(6): e5916.
• Plummer IH et al. 2017. Temporal patterns of chronic wasting disease prion excretion in three cervid species. Journal of General Virology. 98:1932-1942.

It is impossible to eliminate the risk of CWD. Instead, we have to consider what we can do to reduce risk, keeping in mind that we only have control of a few things that occur on the landscape. Both have risk, but a bait pile has more risk for disease spread because it concentrates deer in a smaller area. It is reasonable to point out that deer will congregate in a farm field, around a silage pile, etc., but we as hunters can only control what we do. By prohibiting hunting over bait, we reduce the number, duration, and intensity of congregations. This does not solve the problem of CWD, but at a landscape level, it has meaningful effect in reducing the risk of spreading CWD within an area.

A statewide ban would be a more proactive option for reducing the risk of CWD spread within an area compared to a regional ban. However, the Department must balance the risk of CWD with the wishes of hunters outside CWD positive areas. Previous discussions have concluded that there is not enough public support to implement a statewide baiting ban.

All evidence of the last few decades indicates that this is not true. CWD follows a classic epidemiologic pattern where it shows up in an area, and slowly spreads from that “hotspot” while also increasing in prevalence within that population. The last 10-20 years of disease surveillance across the country has established this.

The spread of CWD within a population is slow and insidious. It can take a long time to reach a threshold, above which, actual impacts are observed. What has emerged in the last few years is that CWD-related mortality is now recognized as the major cause of population declines in some herds. We aren’t at that threshold in North Dakota yet and our aim is to never get there. Some research papers documenting this:

• Edmunds DR et al. 2016. Chronic wasting disease drives population decline of white-tailed deer. PLoS ONE. 11(8): e0161127.
• Monello RJ et al. 2014. Survival and population growth of a free-ranging elk population with a long history of exposure to chronic wasting disease. The Journal of Wildlife Management. 78:214-223.
• DeVivo MT et al. 2017. Endemic chronic wasting disease causes mule deer population decline in Wyoming. PLoS ONE. 12(10):e0186512.

Maintaining a lower deer density is one approach to slowing the spread of CWD within an area and reducing the likelihood of an infected deer dispersing and introducing CWD to a new area. In order to do this, Game and Fish has issued more licenses in 3F2 than otherwise would have been the case over the past several years. Hunter success has remained steady in that unit, but we need hunters to help maintain lower densities.

Game and Fish has and will continue to use lessons learned from other states, as well as the best available scientific evidence to make decisions on how to address the issue of CWD in North Dakota. There are few examples where depopulation of a wild deer herd was feasible or effective, and we have no current plans to take this approach. However, wildlife management is dynamic. If a new scenario was to occur that would potentially warrant depopulation in order to save the rest of the herd, all management options would be considered.