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The Blood Supply

Making the Blood Supply Safer

Enhancements to the safety of blood transfusion over the last decade have been dramatically effective, especially with regard to reducing the likelihood of a transfusion-transmitted infection. The most important contributors to this safety are the extensive health history questionnaires that all donors must complete and the highly sophisticated laboratory testing that all donated blood undergoes.

Blood storage freezerAlthough any further increases in safety may be so small that it will be difficult to do studies large enough to reveal any improvement, researchers are focusing their attention in two areas. Bacterial contamination is a rare problem that occasionally complicates platelet transfusions. Part of the reason for this is that platelets have to be stored at room temperature, since they are damaged by refrigeration. Other blood products are stored at colder temperatures that would ordinarily discourage bacterial growth. Research aimed at identifying platelets that are contaminated with bacteria has taken a number of different directions. These include rapidly culturing platelets before they are released for transfusion; looking for changes in oxygen concentration of stored platelets that contain bacteria; testing for the presence of bacterial proteins in stored platelets; and using dielectrophoresis, a method which relies on the different behavior of bacteria in an electric field.

The other area for current research into improvements in transfusion safety involves pathogen detection and inactivation. The term "pathogen" recognizes the fact that while viruses and bacteria are usually the culprits, if a transfusion-transmitted infection occurs, other organisms, such as parasites, are also implicated, though rarely. Research in this area includes studies that safely add chemical compounds, which selectively target and destroy the pathogens. Various methods that are under investigation, however, require significant changes in how blood is processed before it is distributed for transfusion. For example, one procedure requires that blood be exposed to ultraviolet irradiation after the addition of a pathogen-targeting chemical. Much attention has to be paid, whichever process is being used, to ensuring that blood is washed free of any of the additives that were used to inactivate contaminating organisms.

Merlyn H. Sayers, M.D., Ph.D
Special Projects Work Group,
Scientific Section Coordinating Committee
American Association of Blood Banks (

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