Creutzfeldt-Jakob Disease is a very rare and incurable degenerative neurological disorder that is ultimately fatal. It is the most common of the transmissible spongiform encephalopathies. Transmissible spongiform encephalopathy diseases (also known as prion diseases) are caused by a unique type of infectious agent called prions, an abnormally structured form of a protein found in the brain. Other prion diseases include Gerstmann-Straussler-Scheinker syndrome (GSS), fatal familial insomnia (FFI) and kuru in humans, as well as bovine spongiform encephalopathy (BSE) and scrapie in animals. This book presents the latest research in this field.