Safety of blood products from infectious disease agents
A major topic for the safety of blood is the potential transmission of infectious disease agents to recipients via blood transfusion. During the last half century, the 3 major viruses HIV, HCV and HBV have been particularly the main focus for the development of diagnostic tests to prevent such agents entering the pool of blood products.
Currently HBV is still on the forefront of research in the blood transfusion community of one of the main topics is. Indeed in 2019 the safety of blood products in respect of HBV is still greater than 10 times lower than that determined for HCV and HIV. The question of the infectious dose required for the transmission of the virus to recipients, especially in the case of so called occult Hepatitis B infections (OBI), has not yet been answered. In Switzerland anti-HBc screening is not routinely performed. On the other hand it is known that around 2.5% of the current donor population is anti-HBc positive and have thus been in contact with the virus within their lifetime. Thus, there is a considerable risk that low level HBV transmissions can occur. The question to the minimal infectious dose required to lead to an infection remains and is a focus of our ongoing investigations.
During the last decade efforts to improve the safety of blood products in industrial countries have primarily focused their attention on the emerging viral pathogens (such as West Nile Virus (WNV), Chikungunya virus, Usutu virus, and other arthropod-transmitted viruses) or parasites (such as Plasmodium spp. T. cruzi, Babesia spp., etc.). Furthermore the (re)emerging viral infectious disease agents, such as Hepatitis A virus (HAV), Parvovirus B19 (PV-B19), Cytomegalovirus (CMV) and Hepatitis E virus (HEV), have merged into the focus again. Currently studies of the epidemiology of CMV and HEV in the donor population have led to the calculation of residual risks for these viruses. As an outcome to these calculations, research decisions on the national level are currently being deliberated on how to deal with these threats in order to provide adequately safe enough blood products but in a cost-efficient manner.