Blood donor selection and screening: strategies to reduce recipient risk.

Various measures are taken to ensure the safety of the blood supply. Donor selection begins with education of the public about transfusion-transmissible diseases. Potential donors must answer a questionnaire designed to identify specific risk factors for these infections. The questionnaire is the only line of protection against certain infections for which no testing is performed, such as malaria, babesiosis, leishmaniasis, and Chagas disease. All donations are tested for the presence of antibodies to HIV-1 and -2, HCV, HTLV and syphilis, the hepatitis B surface antigen (HbsAg), the p24 antigen (HIV), and also for HIV and HCV nucleic acids. The introduction of new and improved screening tests for transfusion-transmissible diseases has led to remarkable improvement in the safety of the blood supply, with substantial shortening of the window period for HIV, HCV, and HBV infections. The current challenge of the industry is to reduce even further the small but significant risk of bacterial contamination of platelet components. Finally, some safety measures are purely precautionary, such as the deferral of donors who have traveled to certain countries affected by the bovine spongiform encephalopathy (BSE).