1a Virus transmission by allogenous blood and blood components

Infectious agents, especially viruses, can be transmitted by human blood products to recipients. Of major importance are viruses such as human immunodeficiency virus 1 and 2 (HIV-1/2), hepatitis B (HBV) and hepatitis C virus (HBC), and human T-cell leukaemia virus type I and II. Also, other viruses such as cytomegalovirus, Epstein-Barr virus, human parvovirus B19, and hepatitis A and G virus can be transmitted by infected blood products. Various methods are applied to prevent the transmission of blood-borne agents to recipients, for example donor selection, testing for various infectious agents of all blood donations and viral inactivation of plasma derivatives. With all these precautionary measures, the estimated risk for infection by screened blood products in Europe and the USA is approximately 1 in 50 000 to 1 in 600 000 (for HBV, HCV and HIV-1/2) per transfused blood product. In the future, the safety of blood products will probably be increased by testing all blood donations with nucleic acid amplification techniques and by (photo)chemical decontamination of cellular blood components.