[Prion diseases].

Creutzfeldt-Jakob disease, kuru, Gerstmann Sträussler Scheinker syndrome and fatal familial insomnia in humans, as well as scrapie and bovine spongiform encephalopathy, in animals, are fatal disorders of the central nervous system that are part of the group of transmissible spongiform encephalopathies, (TSE) or prion diseases. Neuronal intracellular spongiosis and the accumulation of abnormal, protease resistant prion protein in the nervous central system characterize TSE. The conformational change of a host protein, prion protein, into a pathological isoform is the key pathogenetic event in TSE. Despite their relative rarity, prion diseases have a great impact on the scientific community and society in general. There are two major reasons: first, the heretical hypothesis of a disease transmitted by an "infectious protein" in the absence of nucleic acid, the basis of the conformational transmissibility concept; second, the panic originated from the appearance of new variant Creutzfeldt-Jakob disease and the evidence linking it to the exposure of humans to bovine spongiform encephalopathy via food contaminated by affected bovine tissue. Novel therapeutic approaches are examined.