Chronic Wasting Disease
What is Chronic Wasting Disease?
Chronic Wasting Disease (CWD) is a neurological disease affecting deer, elk and moose that attacks the brain and is characterized by progressive weight loss, abnormal behavior and eventual death. CWD belongs to a group of diseases called transmissible spongiform encephalopathies (TSEs). CWD is similar to scrapie in sheep and bovine spongiform encephalopathy (also known as mad cow disease) in cattle as well as variant creutzfeldt-jakob disease (vCJD) in humans, but CWD is a distinct disease known only to affect members of the deer family. These disorders are thought to be caused by abnormal proteins or “prions”.
What Does CWD Look Like?
and elk infected with CWD during clinical stages may exhibit symptoms including emaciation, lowered head and ears, “blank” facial stare, excessivethirst accompanied by excessive urination,decreased food consumption leading to poor body condition, teeth grinding, excessive salivation, wide-based stance, and incoordination. Affected animals may be seen walking repetitive courses. The clinical disease is often more subtle and prolonged in elk than in deer.
Can Humans be Affected with CWD?
There have been no reported cases of humans being affected with the prions associated with CWD either through contact with infected animals or by eating the meat of infected animals. Studies have shown that humans living within endemicareas have not shown any significant increase in the number of CJD or any other documented prion disease resulting fromCWD exposure. Although there has been no identifiable risk to humans from consuming animals infected with CWD, it cannot be said with 100% certainty that CWD will not transmit from cervids (deer and elk) to humans so it is always important to take the proper measures to avoid exposure to the CWD agent.
Surveillance in Efforts in Arizona
Surveillance in Arizona has thus far shown that CWD is not present in our deer or elk populations. The Game and Fish Department has implemented steps to reduce the potential for this disease so that it doesn't establish itself in Arizona. Extra efforts are being made to focus on areas bordering CWD-positive states (CWD-positive map). Protocols have been established should the disease find its way across our borders.
Arizona has been divided into risk assessments based on proximity to positive states. Game Management Units (GMUs) have been grouped together based on their locations to these areas and broken down into high risk, medium risk, and low risk (see map below).
Within each risk area, rough population estimates of cervids (mule deer, white-tailed deer, and elk obtained from the Department’s survey data) were used in an epidemiological model to calculate a desired sample size that would allow for the detection of a 1% prevalence of CWD at a 95% confidence interval.
The Department began conducting CWD surveillance in 1998 and has since collected over 16, 000 samples. Each year samples are collected from hunter harvested and targeted deer and elk throughout the state. Hunter harvested samples are typically collected by means of taxidermists and meat processor participation as well as through check stations and regional drop-offs. Targeted sampling consists of samples collected from roadkill and those dispatched by Wildlife Managers due to the animal exhibiting signs consistent with CWD.
Hunters can assist by bringing in the head of their recently harvested deer or elk to any Game and Fish Department office between the hours of 8 a.m. and 5 p.m., Monday through Friday. Place the head in a heavy plastic garbage bag for delivery, and keep it cool and out of the sun. If the weather is warm, it is best to either bring in the head within a day of harvest or keep it on ice in a cooler before delivery.
When submitting heads for sampling, please provide accurate, up-to-date hunter information (name, street address, city, state, zip and phone number) as well as hunt information (hunt#, permit #, game management unit harvested in, county, state, and hunt license) as this information is crucial should a positive CWD sample occur.
In order for Arizona to maintain its CWD-free status, hunters are advised to take certain precautions when hunting in state or out of state. The department is concerned that CWD might be inadvertently brought into our state through the transport of infected animal tissues. Precautions that should be taken before bringing any harvested animal back into Arizona include:
- If you intend to hunt out of state, contact the wildlife agency in the area you intend to hunt. Several states have regulations on carcass movement.
- Bone out the meat and package (either commercially for privately); do not cut into the spinal cord or remove the head; do not quarter (or other method) the carcass with any of the spinal column or head attached
- Do not bring the brain, intact skull, or spinal cord back into Arizona
- If you wish to take the antlers attached to the skull plate, thoroughly scrape and clean the tissue from the skull plate using a knife or brush and bleach. Thoroughly clean all utensils afterwards with bleach.
- Animal skins or capes (without skull) do not need any further treatment.
- Sawn-off antlers – with or without velvet- do not need further treatment
- Upper canine teeth of elk (“ivories”) do not need further treatment
- Finished taxidermy heads do not require further treatment
The following precautions should be taken when pursuing or handling deer or elk:
If you have your deer or elk commercially processed, request that your animal is processed individually, without meat from other animals being added to meat from your animal.
- Do not shoot, handle or consume any animal that is acting abnormally or appears to be sick. Contact the Arizona Game and Fish Department at 1-800-352-0700 if you see or harvest an animal that appears sick.
- Wear latex or rubber gloves when field dressing your deer or elk.
- Bone out the meat from your animal. Don't saw through bone, and avoid cutting through the brain or spinal cord (backbone).
- 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.
Carrington Knox, Wildlife Disease Biologist
Arizona Game and Fish Department
5000 W. Carefree Highway, Phoenix, AZ 85086-5000
Phone: (623) 236-7674 E-mail: ChronicWastingDis@azgfd.gov