Emerging viral infections relevant to transfusion medicine

The development of new technologies leads to the discovery of new viruses. For each of these new infectious agents relevance to transfusion needs to be assessed. The questions to be answered are transmissibility by transfusion, pathogenicity, prevalence in blood donors, persistence and the availability of screening assays. Since 1995, three new viruses have been identified and extensively studied. GB virus-C/hepatitis G virus (GBV-C/HGV), a relatively rare virus with some homology with and epidemiological features of HCV, was thought to be related to post-transfusion hepatitis but was proven to be unrelated to hepatitis and is still in search of a disease. Human herpes virus-8 (HHV-8) is a major factor in the pathogenesis of Kaposi’s sarcoma and other tumours related to immunodeficiency. HHV-8 transmission by organ transplantation, but not by transfusion, has been demonstrated. The TT virus (TTV) is a ubiquitous virus infecting a very high proportion of humans in infancy. No clinical symptoms or pathogenicity is attached to TTV. To date, none of the emerging viruses have been proven relevant to transfusion.