To prevent transfusion transmission of blood borne infections, each unit of collected blood are routinely tested for Hepatitis B (HBV) surface antigen, Hepatitis C Virus (HCV) antibody, Human Immuno-deficiency Virus (HIV) types 1 and 2 antibodies and antigen, Human T-Lymphotropic Virus (HTLV) types I & II antibodies and Syphilis antibody. Blood units that are tested negative for all these infectious markers can be selected for clinical transfusion. In addition, selected donations are also tested for cytomegalovirus (CMV) antibodies for the purpose of providing CMV negative blood for clinically indicated patients.
Nucleic Acid Testing (“NAT”) technology is a sensitive test that is capable of amplifying a small part of viral or other genetic material over a billion fold. Therefore it is possible to detect minute quantity of viral particle in a blood sample. To enhance blood safety, the BTS has employed NAT to screen blood donor samples for HCV and HIV RNA since mid 2002. With advance in testing technology, the application of NAT can also be extended to mass screening of individual blood donations for HBV DNA from 2007. This new technology is able to significantly reduce the window period for detecting HIV, HCV and HBV infections in donated blood; the window period for HCV infection can be reduced from 70 days to around 5 days, HIV infection from 22 days to around 6 days and HBV from 59 days to around 20 days.