Prion diseases and blood transfusion

Prion diseases are lethal disorders, some of which are transmissible by inf ectious route. Experimental data concerning neuroinvasion indicate that the re is a viremia during the migration of the prion agent to the central nerv ous system. The possibility of accidental transmission via blood products a nd therefore potential transfusion risk thus arises. The analysis of experi mental and epidemiological data available at present contributes to the fol lowing conclusion: the potential and theoretical risk for contamination fro m blood products is not null but mathematically very low, there is no indis putable experimental proof for that risk via systemic route and no case is definite and the risk is probably linked to leukocytes, and especially B ly mphocytes. These conclusions are reassuring but nevertheless justify strict epidemiological survey and a reasonable discussion for each transfusion. S ome groups of people have to be excluded from blood donors. (C) 1999 Elsevi er, Paris.