Prevention of infections transmissible by blood derivatives.

Agents that are transmissible by blood or its derivatives typically have long incubation periods, may often be asymptomatic for several years and can set up carrier or latent persistent infections. Examples are hepatitis B virus (HBV), hepatitis C virus (HCV), the human immunodeficiency viruses (HIV 1 and 2) and cytomegalovirus. The prevention of transfusion-transmitted infection (TTI) is based on the exclusion of potential blood donors who are not fit and well, the education of donors to exclude themselves if they are at risk of contracting TTIs, the laboratory screening of all blood donations for evidence of infection with a range of potential TTIs, physical removal of white cells in those cases where the agent is cell associated, viral inactivation procedures for pooled plasma derivatives, detection of viral genomes in plasma pools and the avoidance of unnecessary transfusions.