PREVENTION OF TRANSFUSION-ASSOCIATED CHAGAS-DISEASE - EFFICACY OF WHITE CELL-REDUCTION FILTERS IN REMOVING TRYPANOSOMA-CRUZI FROM INFECTED BLOOD

Background: Transfusion-associated Chagas' disease (TA-CD) is a worldw ide problem. Measures adopted to prevent TA-CD include the clinical an d serologic screening of blood donors and/or the inactivation of Trypa nosoma cruzi present in collected blood, using gentian violet as the t rypanocidal agent, This study investigated the efficacy of white cell- reduction filters in removing T. cruzi from infected blood. Study Desi gn and Methods: Human blood was contaminated with 2 or 150 T. cruzi pa rasites per ml and then left unfiltered or filtered with white cell-re duction filters that provided either 2, 3, or 6 log(10) white cell rem oval. The efficacy of the parasite removal of these filters was evalua ted by microscopic enumeration of active forms of T. cruzi both in viv o and in vitro. The in vivo experiments were done in Swiss mice that h ad been intraperitoneally inoculated with T. cruzi-infected human bloo d. The in vitro experiments were performed with fresh human blood that had been deliberately contaminated with T. cruzi. Results: The number of parasites seen in mice inoculated with unfiltered blood containing 2 or 150 parasites per ml was significantly higher than the number of parasites seen in mice inoculated with blood from the same sample, bu t filtered with white cell-reduction filters providing 3 or 6 log(10) white cell removal. Fifty to 70 percent of the mice given T. cruzi-inf ected (2 parasites/ml) filtered blood did not develop T. cruzi infecti on. In vitro, the use of white cell-reduction filters, providing 2, 3, or 6 log(10) white cell removal, significantly reduced the number of parasites seen in culture. Conclusion: The present experimental data p rovide evidence that white cell-reduction filters are effective in red ucing the number of parasites in T. cruzi-infected blood and that this efficacy depends, in part, on the concentration of parasites in the a rtificially infected blood. Properly designed clinical studies of know n carriers of T. cruzi must be conducted to determine whether the use of white cell-reduction filters may be an alternative method of reduci ng the incidence of TA-CD.