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

Abstract

Background and Objectives 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. Materials andMethods 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.Results Of the repeat reactive donors, 2696 (> 99AE99%) 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 7AE9 and 5AE5% 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 0AE9 per million donations. ConclusionThe 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.Key words: blood donor, malaria, screening, transfusion. IntroductionMalaria is a protozoan parasitic infection of humans resulting from infection by one or more of the five species of the genus Plasmodium (P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi) [1,2]. Transfusion transmitted malaria (TTM), although rare, continues to pose a risk to blood services worldwide with recent transmissions invariably resulting from 'semi-immune' donors who may carry undetectable levels of parasites without overt symptoms [3][4][5][6][7][8][9]. Of the five Plasmodium species, P. falciparum is the most serious transfusion risk since it is fatal in approximately 10% of patients infected in this way [10]. Although malaria is not endemic in Australia, there are between 500 and 900 cases of imported malaria annually constituting an ongoing TTM risk [11]. The last documented Australian TTM case, a fatality associated with P. falciparum, occurred in 1991 [12], this being the first reported transfusion Due to the lack of a suitable high throughput laboratory test, screening for malaria in Australian blood donors prior to July 2005 relied on collecting a comprehensive medical and travel history as part of the donor assessment process and exclusion of cellular blood components from those with potential risk exposure to Plasmodiae. At that time, the Australian Red Cross Blood Service (ARCBS) Guidelines for the select...

A case report of transfusion-transmitted Plasmodium vivax malaria from an asymptomatic donor to a premature newborn

“…Recientemente, en Australia, se redujo el período de restricción a cuatro meses y se anexó la tamización de anticuerpos para malaria a los donantes en riesgo, con lo que se logró que las tasas de transmisión relacionadas con la transfusión se mantengan bajas (0,9 por millón de donaciones), recuperando de paso 64.967 unidades de glóbulos rojos y 7.398 unidades de plaquetas, que representan 7,9 % y 5,5 % de su producción anual, respectivamente (21). El análisis retrospectivo de los donantes implicados en este tipo de transmisión, ha confirmado la presencia de altos niveles de anticuerpos en ellos.…”

Current concepts in molecular testing

“…For these chronic carriers, NAT screening would be of limited contribution, since in general they harbour very low levels of parasitaemia. Seed et al in Australia detected only two PCR positive individuals among 2697 donors serologically reactive for Plasmodium sp antibodies [37] while Leiby et al, using several blood drawings of large volume, obtained PCR positive results in 63% out of 52 donors seroreactive for T. cruzi antibodies [38]. In contrast, in endemic areas, due to the high prevalence, it would be unrealistic to adopt serological tests for Plasmodium sp.…”

Transfusion-transmitted malaria: case report of asymptomatic donor harboring Plasmodium malariae

“…SEED et al 31 used an enzyme-linked immunoassay (Newmarket) and the results pointed out to the usefulness of a screening strategy combining antibody testing with a 6-month cellular component restriction period for donors with a declared malarial risk. Recently the restriction period was shortened to 4-month combined with a sensitive antibody screening test for donors with malarial risk and the risk of transfusional malaria in Australia remains low 30 . In France, a multicentre study was performed in nine blood banks to compare IFAT and DiaMed ELISA, obtaining a rate of concordance of 92.6% in retrospective samples and 97% in the prospective group, corroborating with the potential use of ELISA test in blood bank screening, as an alternative to the IFAT in non-endemic areas 14 .…”