[Transfusion-transmitted diseases].

Transfusion-transmitted infection has long been one of the major adverse reactions in blood transfusion. However, the implementation of effective screening tests makes it minor at present. Especially NAT (nucleic acid amplification test) is highly sensitive in detecting infection with HBV, HCV and HIV-1. Now the residual risk of post-transfusion hepatitis has reduced to as low as 1:100000. Not all of the blood-borne infections are included in the category of transfusion-transmitted infection, since donors are interviewed and examined for their health statuses. As to the organisms screening is not prepared or the window period infection, donor interview would be especially important. Namely, only the organisms that are cryptogenic and induce little symptoms are included in the category of transfusion-transmitted infection. Virus infections which tend to be asymptomatic are among them, such as HBV, HCV, and HIV, as well as bacteria and protozoan infection of long latency and probably prions. At present bacterial contamination is one of the major risks of blood transfusion. West Nile virus (WNV) and hepatitis E virus (HEV) have emerged as members of transfusion transmitted infection. Other newly developing blood-borne infections will be a menace to the blood safety, and thus we should be ready to prepare for preventing them. Selection of the countermeasures should be based on cost benefit analysis. Inactivation of organisms is under study, but its distant adverse effects are not yet clear. Vaccination and the clearance of organisms from the general population would be a more basic countermeasure.