Reducing the risk of transfusion-transmitted rickettsial disease by WBC filtration, using Orientia tsutsugamushiin a model system.

BACKGROUND

Careful donor screening and infectious disease marker testing have significantly reduced the incidence of transfusion-transmitted diseases and improved the safety of the blood supply. However, transfusion-transmitted diseases resulting from the use of asymptomatic yet infectious donors continue to put patients at risk. This study was undertaken to determine if third-generation WBC filters could remove Orientia tsutsugamushi-infected cells from contaminated blood.

STUDY DESIGN AND

METHODS

Packed RBCs were inoculated with human MNCs infected with O. tsutsugamushi at levels estimated to occur in asymptomatic infectious donors. WBC reduction was accomplished with a third-generation WBC filter. Prefiltration and postfiltration specimens were collected, serially diluted, and injected into mice to determine the infectivity of the samples.

RESULTS

Mice receiving WBC-reduced packed RBCs showed no signs of illness or markers of infectivity, which suggested that a reduction of as much as 10(5) infectious rickettsiae could be achieved by filtration.

CONCLUSION

The high-efficiency, third-generation, WBC-reduction filters that were tested may provide protection against the transfusion transmission of scrub typhus rickettsiae by removing from contaminated blood cells that contain intracellular bacteria.