Background
Chronic wasting disease (CWD) is a progressive, fatal, neurodegenerative disease of cervids (deer, elk, reindeer, and moose). The infectious agent is a misfolded form of the endogenous prion protein. The normally folded form of the protein is found throughout the body, with the highest concentration in the brain, spinal cord, and lymphoid tissues. With infection, the misfolded form accumulates in the highest concentration in the brain, spinal cord and lymphoid tissues along the alimentary tract. Clinical signs of CWD infection can take years to develop, prior to which animals without clinical signs can still spread disease. Chronic wasting disease belongs to a family of diseases called prion diseases or transmissible spongiform encephalopathies (TSEs). Other TSEs include bovine spongiform encephalopathy (BSE) in cattle, scrapie in sheep and goats, and Creutzfeldt-Jakob disease in humans.
Chronic wasting disease continues to spread in farmed and wild cervids and is of particular concern because the disease can spread at the interface between farmed and wild cervids. CWD is spread through direct animal-to-animal contact via infected body fluids and/or excreta, or indirectly through contact with CWD-contaminated items in the environment, such as soil and other fomites; however, all modes of transmission have yet to be determined.