cwd

CWD, short for chronic wasting disease, is a progressive neurodegenerative illness of cervids, a group that includes white-tailed deer, mule deer, elk, moose, and reindeer. It is caused by misfolded prion proteins that accumulate in the brain, spinal cord, and certain lymphoid tissues, leading to severe brain damage and, ultimately, death. CWD is classified as a transmissible spongiform encephalopathy, a family of diseases that also includes bovine spongiform encephalopathy and Creutzfeldt-Jakob disease in humans.

The disease spreads through both direct contact between animals and indirect environmental exposure. Prions can be shed in saliva, urine, feces, and decomposing tissue, and they can persist in soil and other environments for years, facilitating long-term transmission. Prion persistence contributes to sustained disease cycles in wild and captive cervid populations.

Clinical signs in infected animals are gradual and include weight loss despite adequate food intake (sometimes described as wasting), behavioral changes such as increased curiosity or listlessness, decreased response to stimuli, tremors, ataxia, and eventual debilitation and death. Because signs resemble other conditions, laboratory testing is required for confirmation.

Diagnosis typically relies on postmortem testing of brain tissue, especially the obex region, and may include immunohistochemistry, ELISA, or Western blot. Live-animal testing exists but is limited in sensitivity and scope. Surveillance programs monitor wild and captive populations to track prevalence and trends.

There is currently no evidence of natural transmission to humans, but public health guidance emphasizes avoiding meat from suspect or positive animals and following local testing and disposal recommendations. Control measures focus on surveillance, movement restrictions, carcass handling precautions, and efforts to minimize feeding and congregation of cervids to reduce transmission risk.