[The history and classification of human prion diseases].

INTRODUCTION AND DEVELOPMENT: The history of prion diseases is one of the most exciting chapters of the story of medicine in the twentieth century. It began in the nineteen twenties when Creutzfeldt (in one patient) and Jakob (in five patients) described a clinically polymorphic cerebral syndrome with a subacute or chronic course and fatal outcome. Although later reviews of these pioneer studies have cast doubt on the nosology of some of these cases, the eponym has been maintained over the years. It is even possible that the miliary sclerosis described by Gowers in the nineteenth century was in fact a spongiform encephalopathy. Subsequently the nosological limits of Creutzfeldt-Jakob disease remained ill-defined. This explains the large number of names given to it whilst it continued to be included in the chapter on degenerative conditions of the nervous system. Perhaps the turning point was when, in the nineteen sixties, Carleton Gajdusek et al showed that it was transmissible. Previously Gajdusek and Zigas had (in 1957) described the disease kuru in a group of indigenous cannibals in Papua (New Guinea). The possibility of a parallel between this kuru and the scrapie of sheep (in which transmission had been proved twenty years before) led them to experiment and eventually prove its infectious nature. Over the following years, reports of iatrogenic cases with different routes of transmission gave further proof. The absence of conventional microorganisms responsible for this group of conditions led Prusiner (in 1982) to suggest the theory of the infecting proton or prion.

CONCLUSION: This theory led to better understanding of several pathological and physiopathological aspects, however, we are aware that the full story of prion diseases is still being written at the present time.