[The blood-born viral infections].

Recently it has become urgent to establish a risk control system against emerging and re-emerging infectious diseases. Many of the emerging and re-emerging infectious diseases such as AIDS and viral hepatitis, are induced by viral infection via blood. The main causative agents of blood-born viral infection are hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), human T cell leukemia virus type1 (HTLV1), cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human parvovirus B19. They play the main role in viral hospital infections. The risk of them being transmitted by the transfusion of screened blood is very low, but it is always possible that infection may occur in a window period even after extensive blood screening tests. EBV has been recognized as a less serious infectious agent than CMV. Nowadays, biotechnology has revealed the broad spectrum of EBV related diseases as chronic active EBV infection, compromised lymphoma, gastric carcinoma and other lymphoproliferative disorders. There would be some immunocompromised cases needed monitoring after transfusion/transplantation as same as CMV infection. Double infection or co-infection of EBV and CMV are shown to be occasional. The most important tasks for risk control of hospital acquired infectious diseases are to prevent second drug related AIDS and prion infection due to the transplantation of dura mata derived from patients with Creutzfeldt-Jakob disease, and to prevent of needle stick infections. Therefore it is necessary to establish a network communication between clinical laboratories, institutes and public health organizations for more rapid and adequate care with rapid diagnosis by molecular analysis.