Virus safety of blood and plasma products in Germany - State of knowledge and open problems

The first part of the paper covers general aspects of virus safety. Current measures to avoid transmission of infections by transfusion are donor sele ction, including confidential unit exclusion, laboratory testing, and patho gen inactivation. Since testing and inactivation cannot guarantee the compl ete absence of pathogens for several reasons, appropriate selection of bloo d donors with as low as possible risk of transmissible infections still app ears desirable. However, exclusion criteria are very unspecific with respec t to the true donor infectivity, and the influence on the virus safety of b lood products remains unknown. Furthermore, there are indications that many donors do not fully comply or actively bypass the selection procedure. It appears necessary to reevaluate current donor selection in order to reduce exclusion criteria to those which prove to be important and thus improve co mpliance of donors. A matter of debate is which tests have to be applied fo r testing of donors. Problems arise if a donor becomes test-positive just a fter the screening test was changed to a more sensitive procedure (the form er test might have been false-negative). Open questions are:'How perfect ne eds to be confirmation of positive screening results for epidemiological ev aluation?' and 'Is ALT testing still necessary?'. The pressure to introduce any test promising a marginal benefit at enormous costs could be reduced b y a no-fault compensation scheme as introduced in Italy. The second part of the paper covers current problems with special viruses such as HBV (incide nce, necessity of anti-HBc testing), HCV (residual risk, additional transmi ssions through anti-D immunoglobulin), new candidate viruses for non-A to - E hepatitis, the possible efficiency of HIV nucleic acid amplication testin g, HTLV, and parvovirus B19 transmissions.