Emerging viral infections‑-a potential threat for blood supply in the 21st century.

During the last 25 years the safety of blood products has improved dramatically with regard to infectious risk, notably to the threat represented by retroviruses (HIV and human T‑cell lymphotropic virus) and hepatitis B and C viruses. However, both residual and emergent viral infections are still responsible for contaminations in recipients of blood products. Along with other viruses (human herpesvirus‑8, human parvovirus B19, hepatitis A and E viruses, etc.), special attention has recently been paid to emerging arboviruses, such as West Nile virus in North America, and Dengue and Chikungunya viruses in Europe. Another blood‑linked risk, notably in the United Kingdom and France, is the prion agent responsible for the variant form of the Creutzfeldt‑Jakob disease. Hemophilia care has been the model for improvements in the safety and availability of safe blood components free of infectious agents. In this regard, several measures aimed to halt transmission of viruses have been implemented in blood banks, including the exclusion of at‑risk donors, specific sensitive diagnostic tests, leukocyte reduction of labile blood products, and the physical or chemical treatments aiming at nonspecific inactivation of infectious agents potentially present in blood without impairing significantly its physiological properties.