Hepatitis viruses and the safety of blood donations

Since the beginning of blood transfusions concomitant transmission of viral hepatitis has been a frequent and serious side-effect. A first measure to reduce the frequency of transmission was the screening of blood donors for elevated levels of liver enzymes in the blood, which was introduced in Germany in the 1960s, but not in most other countries. After the discovery of hepatitis B virus (HBV), donors in all countries have been screened since the 1970s for its surface antigen (HBsAg). When it was realized that there was at least one other type of virus that was even more frequently transmitted, screening for liver enzymes and HBV antibodies (anti-HBc) was introduced as a surrogate marker in most, but not all, countries in the 1980s. Furthermore, donors at risk for parenterally transmitted viruses were excluded. The discovery of the hepatitis C virus (HCV) genome and the development of sensitive anti-HCV assays has meant that reliable detection of persistently infected HCV carriers has been possible since 1991. Recently infected donors, however, are infectious for several weeks or months before anti-HCV is detectable. Therefore, starting in April 1999 all donations in Germany have to be tested, by nucleic acid amplification tests, for the presence of HCV RNA, although preliminary experience shows that such recent HCV infections are very rare. Newly detected viruses, named GBV-C or HGV and TTV, have been detected in patients with non-A-E post-transfusion hepatitis, but their association with the disease seems to be coincidental. These viruses cause persistent viraemia and are quite prevalent world-wide, but do not cause any known disease. At present, transfusion-transmitted hepatitis has been virtually eliminated, and any improvement in safety will be very small and will require huge costs.