Chronic Wasting Disease (CWD) is a neurological illness affecting deer, elk, and moose (cervids). It raises questions for hunters and consumers about potential transmission to humans through venison. This article provides current information on the disease and safe handling practices.
What is Chronic Wasting Disease?
Chronic Wasting Disease is a fatal neurological disorder caused by prions. These abnormal, misfolded proteins induce normal proteins in the brain and other tissues to misfold. This process leads to the accumulation of abnormal proteins, causing damage that results in a spongy degeneration of the brain. The disease progresses slowly, with an incubation period that can range from months to several years before symptoms appear.
Infected animals exhibit symptoms as the disease advances, including severe weight loss, leading to the term “wasting.” Behavioral changes are common, such as decreased interaction with other animals, listlessness, a lowered head, and tremors. Other signs include excessive salivation, teeth grinding, increased thirst and urination, difficulty walking, and a noticeable loss of fear of humans. CWD is invariably fatal for the infected animal, and there is currently no treatment or vaccine.
CWD spreads among cervid populations through both direct and indirect contact. Direct transmission occurs through animal-to-animal contact, while indirect transmission happens when animals come into contact with contaminated environments. Infected animals shed prions through bodily fluids such as saliva, urine, and feces, which can persist in the environment for years, making areas infectious for extended periods.
Is There a Human Health Risk?
The central question regarding Chronic Wasting Disease is whether it can be transmitted to humans. Currently, there have been no confirmed cases of CWD infection in people. Health organizations, including the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO), continue to monitor the situation closely.
Despite the absence of confirmed human cases, the nature of prion diseases raises theoretical concerns. Other animal prion diseases, like Bovine Spongiform Encephalopathy (BSE), have crossed the species barrier to cause variant Creutzfeldt-Jakob disease (vCJD) in humans. Experimental studies on non-human primates, including squirrel monkeys and macaques, have shown CWD transmission under laboratory conditions, indicating CWD prions can convert human prion protein.
However, other studies, including some on human brain organoids, support a strong species barrier to CWD transmission to humans. While a 2019 study suggested the potential for transmission to humans, overall epidemiological and laboratory investigations have not identified strong evidence for CWD transmission to people. The CDC advises caution, acknowledging that while no human cases have been reported, the possibility of CWD posing a risk to people cannot be entirely ruled out due to the long incubation periods associated with prion diseases.
Safe Handling and Consumption Practices
Given the ongoing research and theoretical concerns, certain precautions are recommended for hunters and consumers to minimize potential exposure to CWD. It is advisable to avoid harvesting any deer, elk, or moose that appear sick or behave abnormally. If an animal shows signs of illness, contact your state’s wildlife authorities.
Testing harvested animals for CWD is an important recommendation, especially in areas where CWD is known to be present. If testing is unavailable or an animal tests positive, do not consume the meat. A “no prions detected” result indicates lower risk, but does not guarantee the animal is CWD-free, as prions may be below detectable levels in early infection stages.
When field dressing and processing animals, wear rubber or latex gloves to prevent direct contact with tissues. Minimize handling and avoid consuming high-risk tissues, which include the brain, spinal cord, eyes, spleen, tonsils, and lymph nodes, as these typically contain the highest concentrations of prions. Bone out the meat and avoid cutting through the spinal column or brain.
It is also important to process each animal individually to prevent cross-contamination between carcasses. Thoroughly clean and sanitize all processing equipment, including knives, with a bleach solution (e.g., 2% bleach or 1 part household bleach to 1-1.5 parts water) for at least 10 minutes to help inactivate prions. For disposal of carcass parts not intended for consumption, double-bag them and send them to an approved landfill or bury them deeply. Normal cooking temperatures do not destroy CWD prions.