National Wildlife Research Center (NWRC)

About CWD

Chronic wasting disease (CWD) was first described in captive deer more than 35 years ago near Fort Collins, CO. Since 1998, CWD has spread to wild and domestic animal populations in several states and provinces. It belongs to the family of diseases known as transmissible spongiform encephalopathies (TSEs), so called because these diseases cause microscopic holes in brain tissue giving it a sponge-like appearance. TSEs include diseases such as scrapie in sheep, bovine spongiform encephalopathy (BSE) in cattle (aka Mad Cow Disease), chronic wasting disease in cervids and Creutzfeldt-Jakob disease in humans. These diseases affect the central nervous system and result in lesions in the brain. The causative infectious agents are modified, rogue proteins called prions.

CWD infects elk, white-tailed deer, and mule deer, but is not known to naturally infect other species of wildlife (including predators and scavengers), livestock, or humans. There is no treatment for CWD and it is typically fatal. The mode of transmission of CWD is not well understood. Transmission from infected animals to uninfected animals via nose to nose contact, saliva, urine and feces are considered the likely routes. Transmission may also occur through environmental contamination. Clinical signs of the disease are not unique and are similar to those for other conditions, such as malnutrition. Infected cervids may not show clinical signs of CWD for several years. Currently, diagnosis of CWD requires testing by immunohistochemical staining (IHC) or ELISA (enzyme-linked immunosorbent assay) of a specific portion of the brain and spinal cord. Also, a tonsil biopsy technique for live mule deer and white-tailed deer, but not elk, has been developed.

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About Chronic Wasting Disease