Chronic Wasting Disease (CWD) is a fatal neurological illness affecting members of the deer family, including white-tailed deer, elk, and moose. Spreading across North America and globally, CWD has raised significant concern among hunters and consumers. The central question is whether this disease can cross the species barrier and affect human health through the consumption of venison. Understanding CWD is necessary to evaluate the safety precautions recommended by public health organizations and wildlife agencies.
Understanding Chronic Wasting Disease
Chronic Wasting Disease is classified as a Transmissible Spongiform Encephalopathy (TSE), caused by infectious, misfolded proteins called prions. These prions are abnormal forms of a normal host protein that accumulate in the central nervous system, causing microscopic holes that give the brain a sponge-like appearance. The disease is progressive and invariably fatal to the infected animal, typically taking 18 to 24 months for symptoms to manifest after initial exposure.
CWD affects cervids, including deer, elk, moose, and caribou. Infected animals often exhibit symptoms such as drastic weight loss, behavioral changes, excessive salivation, and a lack of fear of humans. Prions are shed through body fluids (saliva, urine, and feces) and are notoriously resistant, persisting in the environment, including soil, for years.
Assessing Human Transmission Risk
The primary concern is the potential for CWD prions to transmit to humans through consuming infected meat. Currently, no confirmed cases of CWD infection in people have been reported, and it is not known if human infection is possible. However, public health officials advise caution because CWD belongs to the same family of prion diseases as bovine spongiform encephalopathy (BSE), or “mad cow disease,” which successfully transmitted to humans, causing variant Creutzfeldt-Jakob disease (vCJD). This history demonstrates that the species barrier is not absolute in the context of prion diseases.
Major health organizations, including the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO), recommend against consuming meat from any animal known to be infected with CWD. This recommendation is a precautionary measure driven by the theoretical risk that CWD could cross the species barrier. Experimental studies show that CWD can infect certain non-human primates, such as squirrel monkeys, through consumption of infected tissue. The long incubation period of prion diseases, which can take years or decades to develop, complicates the assessment of risk and monitoring for potential human cases.
Testing and Identification Protocols
Because CWD-infected animals may appear healthy for months or years, testing is the only way to determine the disease status of a harvested animal before consumption. Hunters in CWD-endemic areas are strongly encouraged to have their deer or elk tested before consuming the meat. State and provincial wildlife agencies often run CWD surveillance programs, sometimes requiring testing in specific management zones.
The testing process typically involves submitting tissue samples, most commonly the retropharyngeal lymph nodes or the obex (a specific part of the brainstem). Hunters can submit the entire head or specific tissue samples to designated drop-off locations or check stations. Since turnaround time can take a few weeks, it is advisable to wait for negative results before processing or consuming the meat.
Specific Meat Handling Precautions
Hunters can take specific steps during field dressing and butchering to minimize potential exposure to CWD prions, regardless of whether the animal has been tested. The infectious prions are most concentrated in high-risk tissues. It is recommended to wear latex or rubber gloves when field dressing a cervid and to avoid handling or cutting into these tissues.
High-Risk Tissues
The highest concentrations of prions are found in the following tissues:
- Brain
- Spinal cord
- Eyes
- Spleen
- Lymph nodes
Boning out the meat, separating muscle tissue from the bone without sawing, is a recommended practice to avoid contact with the spinal cord and other nervous tissue. Removing all fat, connective tissue, and lymph nodes during butchering will further reduce the presence of potentially infected material. If using a commercial processor, hunters should request that their animal be processed individually to avoid cross-contamination. Tools and surfaces used for processing should be thoroughly cleaned, as prions are resistant and require strong disinfectants, such as a dilute bleach solution, to be inactivated.