Emerging, re-emerging and submerging infectious threats to the blood supply

Abstract

Although the thrust of this chapter has been to discuss ongoing threats and continuing fears, let us not lose sight of how far the safety of the blood supply has come. Prospective studies have shown that the risk of post-transfusion hepatitis has declined from 30% in 1970 to virtual zero in 2000. Mathematical modelling shows the risk of hepatitis C, after the introduction of NAT testing, to have been reduced to approximately 1 case per 2 000 000 transfusions. The risk of hepatitis B is more difficult to calculate and may still be as high as I in 350 000 transfusions. HTV, transmission, the most devastating consequence of blood transfusion, has now been almost totally eradicated with an estimated incidence of 1 in 2 000 000 million transfusions. These low incidence rates for the previous major infectious scourges of blood transfusion are remarkable accomplishments of advancing technology and stringent regulation. There are still threats to face and perhaps others to come, but excellent strategies are in place to handle them and transfusion risk has been minimized to the extent possible within existing technologies. As the latter improve, the environment is such that they will be applied even if not cost effective by traditional definitions. New technologies might include sensitive point of release testing for bacteria, antibody testing for trypanosomes, a test to detect abnormal prions and gene arrays that will allow simultaneous testing for the genomes of multiple organisms, indeed virtually any organism that might pose significant danger to blood recipients. The ultimate strategy will be to develop inactivation methods that can pre-emptively strike against emerging threats and that can be applied to all blood products without introducing new risks or exorbitant costs. We are in a continuing and evolving battle with the mutational capabilities of infectious organisms. In this struggle, I believe technology will ultimately play the winning hand.