Chronic Wasting Disease

What is CWD?

Chronic wasting disease (CWD) is a fatal neurological disease of deer, elk, and moose that has been classified in the group of diseases called transmissible spongiform encephalopathies (TSEs). The disease is infectious, communicable, and always fatal. Other TSEs include Bovine Spongiform Encephalopathy (BSE) or Mad Cow Disease in cattle, scrapie in sheep and goats, and Creutzfeldt-Jakob Disease (CJD) in humans. TSEs are believed to be the result of the transformation of normal prions (proteinaceous infectious particles) into infectious, self-propagating, abnormal prions. Their shape is transformed in such a way that they cause disease. These abnormal prions are found throughout the deer’s body, but concentrate in the brain, other tissues of the nervous system, and some lymph tissues. They eventually cause degeneration of brain cells, creating microscopic holes in the brain.

What animals are affected?

CWD affects several species in the deer family (cervids). White-tailed deer, mule deer, elk, red deer, moose, sika deer, and reindeer have all been found to be susceptible to the disease. Although a variety of species can be experimentally infected with CWD, there is currently no evidence that the disease can be spread naturally from cervids to livestock.

Where does CWD occur?

CWD was first recognized as a disease syndrome in 1967 in captive mule deer at a wildlife research facility in Fort Collins, Colorado, and was recognized as a TSE in 1978. CWD was diagnosed in free-ranging deer and elk in the 1980s.

Alabama’s first known cases of CWD were found in two hunter-harvested adult bucks killed in Lauderdale County during the 2021-22 hunting season. One additional CWD-positive deer was detected in Lauderdale County during the 2022-23 hunting season. To date, CWD has been diagnosed in free-ranging or captive cervids in 31 states and four Canadian provinces including: Alabama, Alberta, Arkansas, Colorado, Florida, Idaho, Illinois, Iowa, Kansas, Louisiana, Manitoba, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Quebec, Saskatchewan, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia, Wisconsin, and Wyoming. CWD also has been detected in Finland, Norway, South Korea, and Sweden.

Is CWD dangerous to humans?

No case of human disease has been directly linked to CWD. Examination of the available data has led the U.S. Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) to conclude that there is no scientific evidence of CWD infecting humans. However, as a precaution, the WHO recommends people or other animals eat no part of a deer diagnosed with CWD. CDC recommends hunters strongly consider testing deer taken from areas where CWD is known to exist prior to consuming the meat.

How is CWD spread?

Prions are shed through saliva, blood, feces, and urine, which makes direct contact with infected deer a primary route of transmission. In areas where CWD has not been detected, movement of infected, naturally dispersing, free-range animals, movement of infected captive animals, and movement of carcasses or high-risk body parts of infected animals are the most likely routes for the initial infection. In addition, the presence of infected deer over time increases the number of infectious CWD prions shed into the environment (e.g., soil, etc.). There are no known management strategies to mitigate the risk of indirect transmission of CWD once an environment has been contaminated with infectious prions. This makes eradication of CWD very difficult, if not impossible, in areas where CWD has been established for a long period before initial detection.

How can I tell if an animal has CWD?

CWD is insidious and has a prolonged incubation period. Infected animals may not show any evidence of being sick for 12 months or more. The disease attacks the central nervous system of the deer, elk, or moose and presents symptoms, including extreme weight loss, excessive salivation, abnormal behavior, and poor coordination, which are similar to other diseases or illnesses of these deer species, such as brain abscesses and chronic cases of hemorrhagic disease. Diagnosis is made by post-mortem testing of specific portions of the animal’s brain stem (i.e., obex) or lymph node tissue from the throat (medial retropharyngeal lymph nodes). Samples can be screened using an enzyme-linked immunosorbent assay (ELISA) or immunohistochemistry (IHC) testing, but suspect animals must be confirmed using IHC testing at the National Veterinary Services Laboratory (NVSL)). Currently, there is no U.S. Department of Agriculture (USDA)-approved, live animal test for CWD. No effective treatment or vaccine for the disease is known.

What is being done to prevent CWD from reaching other parts of Alabama?

The Division is currently taking several measures to help prevent CWD from reaching other areas of our state. Alabama has had a regulation banning the importation of all cervids (members of the deer family) into Alabama since 1973 and the movement of live cervids within Alabama is closely regulated. Fines for violating these regulations are significant. Investigations in other regions of the U.S. and Canada discovered animal movements among many CWD positive captive deer and elk herds (outside of Alabama). Movement of these infected animals likely was the reason for the disease's spread into many areas where CWD had previously not been found. Halting the movement of live captive deer and elk into and within Alabama is a major step in preventing the disease from reaching our state.

The Alabama Department of Conservation and Natural Resources reminds hunters that the importation of whole carcasses and certain body parts of any deer from any area outside of Alabama or the CWD Management Zone (CMZ) in Lauderdale and Colbert Counties is prohibited. This includes all members of the family Cervidae, including but not limited to: white-tailed deer, mule deer, elk, moose, caribou, fallow deer, axis deer, sika deer, red deer, and reindeer. The importation of high-risk body parts of any member of the family Cervidae is prohibited from all states, territories, or possessions of the United States and all foreign countries. Movement of high-risk body parts outside of the CMZ in Lauderdale and Colbert Counties also is prohibited.

Importation of the following cervid parts is allowed: meat that has been completely deboned; cleaned skull plates with attached antlers, if no visible brain or spinal cord tissue is present; raw capes, if no visible brain or spinal cord tissue is present; upper canine teeth, if no root structure or other soft tissue is present; and finished taxidermy products or tanned hides.

The Division also began an active surveillance program for CWD during the 2001-02 hunting season. Over 18,000 free-range deer have been tested since then. Samples are collected from sick or suspect animals, road kills, and hunter harvested animals. Animals that die in licensed game breeder facilities are also tested for CWD.

What can the public do to help?

Based on past events and the best available science related to the of spread and transmission of CWD, the greatest single threat of introducing CWD into areas of Alabama where CWD is not known to occur is from the illegal importation of infected deer or elk into these areas. The continued prohibition on the importation of live deer and elk, as well as certain high-risk body parts, will greatly reduce the possibility of movement of an undetected case of CWD infecting a greater number of uninfected animals.

Citizens of Alabama can assist the Division of Wildlife and Freshwater Fisheries with its CWD monitoring program. Report any transport of live deer, elk, or other cervids on Alabama's roads and highways by calling Operation Game Watch at 1-800-272-4263. Contacting the Division immediately makes it more likely these animals will be intercepted before they can be released.

Hunters are encouraged to submit their deer for CWD testing. Detecting the disease early when it arrives in previously unaffected areas is essential for slowing the spread of the disease. Hunters may get their deer tested by dropping the deer’s head at one of the many drop off freezers located throughout the state. A map showing the location of each of the drop off freezers is available at the following link: CWD Sampling | Outdoor Alabama

The public also can help the Division in their monitoring program by reporting sick deer. A CWD-infected deer will behave abnormally, showing little of their normal wariness or fear of humans. Infected animals also will become emaciated (skinny). It is important to note that other diseases, including brain abscesses and chronic cases of hemorrhagic disease, may exhibit similar symptoms.

If you spot a deer that exhibits these clinical signs of CWD, report it in one of the following ways. Someone with the Division of Wildlife and Freshwater Fisheries will follow up with you.

• Call the Division of Wildlife and Freshwater Fisheries Office nearest you.
• Call the Operation Game Watch line at 1-800-272-4263.
• Report it online.  

Cooperation and support from hunters, landowners, and others is essential to slowing the spread of CWD in Alabama.

Additional information on Chronic Wasting Disease

Other Sources of Information

Centers for Disease Control and Prevention 

Chronic Wasting Disease Alliance

Southeastern Cooperative Wildlife Disease Study (SCWDS) – SCWDS Briefs Newsletter

Chronic Wasting Disease and Cervidae Regulations in North America