Creutzfeldt-Jakob disease is a very rare incurable neurodegenerative disease leading to fatal brain disorder. It is believed to be caused by abnormal prion proteins that trigger normal proteins to misfold, causing brain damage. Its symptoms are mental deterioration, neurological problems, and dementia. It progresses rapidly, with a median survival time of 4-5 months. Brain biopsy or post-mortem examination is needed for confirmation of the disease. In general, proteins fold into discrete units that perform distinct cellular functions, but some proteins are also capable of forming an infectious conformational state known as a prion. Although often viewed in the context of infectious diseases, prions are more loosely defined by their ability to catalytically convert other native state versions of the same protein to an infectious conformational state. Prions are an enigma amongst infectious disease agents as they lack a genome yet confer specific pathologies. They have caused us to question the universality of the central dogma of molecular biology and to revisit it. Prion diseases affect both humans and animals, the latter including the food-producing ruminant species. This volume is essentially interested in Creutzfeldt-Jakob disease in humans and will not dwell on other inherited prion diseases such as Gerstmann-Sträussler-Scheinker syndrome (a rare, inherited prion disease with a slow progression) and fatal familial insomnia (a very rare, inherited prion disease characterized by severe insomnia and progressive neurodegeneration). It discusses prions and their purported causative diseases as well as prion-mimic diseases. It also presents the needed primers of the scientific bases of the disease and suggests what can be done about it. Interestingly, Parkinson's may be viewed as a prion disease and Alzheimer's as a double-prion disease, although there is no general agreement on this view in the broader scientific community. Further, whereas prions are said to be the 'cause' of prion diseases, I rather view such proteins merely as the by-products of a run-away autoimmune disease, as elaborated in my previous volumes on neurodegenerative diseases.