Minnesota Center for Prion Research and Outreach

Chronic wasting disease is a contagious prion disease affecting deer, elk, moose, and other animals in the cervid family. CWD causes neurological breakdown. It is always fatal.

A prion (pronounced PREE-on) is a protein present in all mammals that helps cells in the body to function normally. When normal prion proteins misfold, they lose this ability and cause disease. Abnormally folded prion proteins can cause normally folded and functioning prions to misfold. Over time, as the misfolded proteins bind together and accumulate, they cause the destruction of brain cells and signs of illness develop. This eventually leads to death.

The transmission of CWD is varied and complex. CWD-causing prions are present throughout an infected deer: in blood, saliva, semen, urine, feces, antler velvet, muscle, and other tissues. Thus, as an infected deer lives on, it can shed CWD-causing prions into the environment through its saliva, urine, and other bodily fluids; infected does can even pass CWD prions on to their fawns before birth. Once the infected animal dies, prions can be released into the environment from the carcass of the animal. The unique shape of CWD prions makes them resistant to degradation and destruction; they can remain infectious in the environment even after many years. We know that healthy deer can become infected when they interact with infected deer or from the environment when it is contaminated by CWD prions. 

Deer that are infected with CWD can appear healthy and normal for a very long time. It can take up to two years for signs of disease to appear, and this is generally only in the final few months. Sick deer might show signs of drinking and urinating more than normal, incoordination, drooling, loss of fear of humans, unusual social interactions with other deer, poor hair coat, and loss of body condition (i.e., they become skinny).

There is currently no evidence that humans have contracted a prion disease from consuming meat from a deer with CWD, but there is some concern for this. Like viruses, CWD prions can change as they infect new deer, and those changes can result in new strains. Because it is very difficult to identify strains of CWD and how they might differ in their risk to people, the general recommendation is that people not eat venison from deer that have CWD.

Unlike other food-borne pathogens, prions are not deactivated/neutralized/removed by freezing or cooking. There is no known way to remove CWD prions from meat. Non-porous food prep surfaces, however, can be disinfected with 2:5 (40%) household bleach to water solution and a 5-minute soak. Porous surfaces, like wood, for instance, cannot be effectively disinfected.

Everyone has a part to play in reducing the spread of CWD. Here are some ways you can help:

Hunters

1. Regulations: Understanding and complying with current regulations for testing, carcass movement, and feeding bans where you hunt is an important part of reducing the spread of the disease. Consult your state or Tribal natural resource agency’s rules and regulations prior to each hunting season. Regulations are updated regularly as new information becomes available, so it is important to review them carefully each year.
2. Testing: Consider having your deer tested, even if it is not mandatory in your hunting zone. If possible, do not eat the meat until CWD test results are determined to be “not detected.”
3. Processing: If you have your harvest processed commercially, request to have your deer be processed and wrapped individually, so as not to mix CWD-positive and CWD-not-detected deer meat. Observe the same precaution if you are doing it yourself and processing multiple animals.
4. Disinfection: Wear disposable rubber or latex gloves when processing your harvest. Use designated stainless steel knives and cutting boards that are not used for other food prep. Prions can be removed from these surfaces with a 2:5 (40%) household bleach to water solution and a 5-minute soak.
5. Disposal: Dispose of deer processing waste responsibly:
   • Use provided dumpsters in CWD-management zones.
   • Use household waste streams going to landfills.
   • Leave remains on the landscape where they were harvested.

Consumers

1. Food prep: CWD prions are incredibly hardy and difficult to destroy. You cannot remove or inactivate them from venison by cooking or freezing the meat. In fact, studies have shown cooking concentrates the prions. If you are able to, choose not to eat meat from CWD-positive animals.
2. Feeding deer: Although it may be difficult, or contrary to your good intentions, observe feeding bans. Deer from different herds may be drawn to a food source in a place they may not otherwise mingle. CWD could be spread from an infected herd to a healthy one in such a scenario.

Don’t hunt or eat venison?

Here are some actions to consider:

1. Follow feeding regulations or guidelines.
   • Feeding can congregate deer, increasing the risk of CWD transmission. By adhering to local regulations, you can help reduce this risk.
2. Support organizations that work to combat CWD.
   • Many organizations, such as wildlife conservation groups and hunting associations, are working to understand and mitigate the spread of CWD. Consider donating to or volunteering with these organizations to help further their efforts.
3. Encourage your state legislators to fund projects that support environmental conservation and CWD management.
   • This can include initiatives such as habitat restoration, wildlife disease surveillance, and research into CWD transmission and management. By advocating for funding, you can help ensure that effective measures are taken to protect deer populations and prevent the spread of CWD.
4. Educate yourself and others about CWD.
   • Raising awareness about the disease and its risks can help promote responsible behavior and encourage others to take action.
5. Report any suspected cases of CWD
   • If you encounter a deer that appears to be infected with CWD—or shows any signs of illness—report it to your local wildlife agency to help track the disease and prevent its spread.