Assessing the safety and efficacy of a test-based, targeted donor screening strategy to minimize transfusion transmitted malaria

Abstract

In 2005, the Australian Red Cross Blood Service implemented a malaria antibody testing based strategy for donors with a history of travel/residence in a malaria endemic country or a past history of malaria. This report assesses the safety and efficacy of the strategy since inception. Eligible blood donors were tested using the Newmarket malarial antibody EIA at least 4 months after their last potential exposure. Where EIA non-reactive their quarantined red cells were considered for transfusion and they were re-instated for cellular component manufacture at their next donation. The efficiency and safety of this strategy were evaluated based on the additional number of components recovered for transfusion and the observed incidence of transfusion transmitted malaria (TTM) respectively. Of the repeat reactive donors, 2696 (> 99.99%) were PCR negative whilst one was PCR positive with very low level parasitaemia. The average number of RBCs and platelets recovered per annum was 64 967 and 7398 representing 7.9 and 5.5% respectively of their annual production. No new TTM cases were recorded and the observed TTM rate of zero was consistent with the upper 95% CI for the pretesting TTM incidence of 0.9 per million donations. The study findings support the efficacy and safety of a targeted screening strategy combining a sensitive antibody screening test with a 4-month cellular component restriction period for donors with a declared malarial risk. The TTM risk in Australia remains low and did not measurably change after implementing the testing strategy.