Strategy to improve malaria surveillance system preventing transfusion-transmitted malaria in blood banks using molecular diagnostic

Abstract

BackgroundMalaria can be transmitted by blood transfusion through donations collected from asymptomatic or parasitic donors. The parasites are released into the bloodstream during its life cycle and will therefore be present in donated blood by infected individuals. All cases of transfusion-transmitted malaria (TTM) notified since 2005 in Brazil were fatal. A good screening tool for Plasmodium spp. detection in blood units must have a high detection threshold, and the prevention of TTM relies entirely on the exclusion of potentially infected donors. However, in Brazilian blood banks, the screening test relies on blood thick smears examination.MethodsThe molecular diagnostic based on mitochondrial DNA (mtDNA) using real time PCR (mt-qPCR) was improved to detect Plasmodium falciparum, Plasmodium vivax, and standardized for use in Plasmodium malariae. The analytic sensitivity of this mt-qPCR methodology was performed using a sample of P. vivax.ResultsThe mt-qPCR was highly efficient, and the analytic sensitivity for P. vivax was determined (0.000006 parasites/µL). This method was tested to detect P. vivax and P. falciparum in individuals from two malaria-endemic areas in Brazil, Amazon region (Pará and Rondônia states), the samples were collected in 10 reference units of two blood banks (Pará/nine cities and Rondônia/Porto Velho), and parasites mtDNA were detected in 10 of 2224 potential blood donors (0.45%). In all 10 positive samples, only P. vivax was detected.ConclusionMolecular diagnostic using mt-qPCR was effective in revealing infected potential donors with good perspectives to be applied as screening routine of asymptomatic carriers for preventing transfusion-transmitted malaria in blood banks.

Use of a NAT-based assay to improve the surveillance system and prevent transfusion-transmitted malaria in blood banks

“…The Brazilian Amazon has large cities with millions of malaria-naïve individuals susceptible to infection. In these regions, a better tool for diagnosing malaria is needed and it is currently challenging to find a technique for screening blood donors that is easy to perform and can screen a large number of samples with high sensitivity [19]. PCR has been shown to be an effective tool for diagnosing human malaria parasites, even in mixed infections, and has proven to be a superior method to microscopy [20,21].…”

The hidden Plasmodium malariae in blood donors: a risk coming from areas of low transmission of malaria

“…Other authors have reported the usefulness of mtDNA qPCR for the detection of P. vivax, P. falciparum and P. malariae , carried out in three different reactions. In a study conducted in the Brazilian Amazon region, 10 of 2,224 donor candidates were positive for P. vivax (0.45%) 16 . Our results detected two cases of P. malariae in 292 donor candidates tested (0.7%).…”

Prävention der Übertragung von Malariaerregern durch Bluttransfusion: ein Update über die Diagnostik und Spendertestung

“…Die PCR wurde hier als effektive Screeningmethode bei Blutspendern in einem Hochrisikogebiet für Malariaerreger eingeschätzt. Durch die PCR-Technik konnten verschiedene Plasmodienerreger, auch in sehr geringer Anzahl, schnell in Blutproben asymptomatischer Spender nachgewiesen werden [21]. Insbesondere der Nachweis von sehr geringen Erregermengen im Blut asymptomatischer Spender, bei denen eine subklinische Malariainfektion vorliegt, ist für die aktuellen Berichte der durch Transfusion übertragenen Malariafälle ausschlaggebend [22].…”