[Prion diseases and blood transfusion].

Prion diseases are lethal disorders, some of which are transmissible by infectious route. Experimental data concerning neuroinvasion indicate that there is a viremia during the migration of the prion agent to the central nervous system. The possibility of accidental transmission via blood products and therefore potential transfusion risk thus arises. The analysis of experimental and epidemiological data available at present contributes to the following conclusion: the potential and theoretical risk for contamination from blood products is not null but mathematically very low, there is no indisputable experimental proof for that risk via systemic route and no case is definite and the risk is probably linked to leukocytes, and especially B lymphocytes. These conclusions are reassuring but nevertheless justify strict epidemiological survey and a reasonable discussion for each transfusion. Some groups of people have to be excluded from blood donors.