Chronic wasting disease (CWD) is a fatal prion disease affecting the central nervous systems of cervids, such as deer, elk, reindeer, sika deer, and moose. Prion diseases are caused by the abnormal folding of the prion proteins that form clumps in the brain. The disease was first detected in Colorado in 1967 and is thought to spread among cervids through contact with saliva and other fluids. It is now found in more than 26 states and two Canadian provinces. A National Academies committee will review the state of knowledge about m...