Abstract
BackgroundWhile sub-microscopic malarial infections are frequent and potentially deleterious during pregnancy, routine molecular detection is still not feasible. This study aimed to assess the performance of a Histidine Rich Protein 2 (HRP2)-based ultrasensitive rapid diagnostic test (uRDT, Alere Malaria Ag Pf) for the detection of infections of low parasite density in pregnant women.MethodsThis was a retrospective study based on samples collected in Benin from 2014 to 2017. A total of 942 whole blood samples collected in 327 women in the 1st and 3rd trimesters and at delivery were tested by uRDT, conventional RDT (cRDT, SD BIOLINE Malaria Ag Pf), microscopy, quantitative polymerase chain-reaction (qPCR) and Luminex-based suspension array technology targeting P. falciparum HRP2. The performance of each RDT was evaluated using qPCR as reference standard. The association between infections detected by uRDT, but not by cRDT, with poor maternal and birth outcomes was assessed using multivariate regression models.ResultsThe overall positivity rate detected by cRDT, uRDT, and qPCR was 11.6% (109/942), 16.2% (153/942) and 18.3% (172/942), respectively. Out of 172 qPCR-positive samples, 68 were uRDT-negative. uRDT had a significantly better sensitivity (60.5% [52.7–67.8]) than cRDT (44.2% [36.6–51.9]) and a marginally decreased specificity (93.6% [91.7–95.3] versus 95.7% [94.0–97.0]). The gain in sensitivity was particularly high (33%) and statistically significant in the 1st trimester. Only 28 (41%) out of the 68 samples which were qPCR-positive, but uRDT-negative had detectable but very low levels of HRP2 (191 ng/mL). Infections that were detected by uRDT but not by cRDT were associated with a 3.4-times (95%CI 1.29–9.19) increased risk of anaemia during pregnancy.ConclusionsThis study demonstrates the higher performance of uRDT, as compared to cRDTs, to detect low parasite density P. falciparum infections during pregnancy, particularly in the 1st trimester. uRDT allowed the detection of infections associated with maternal anaemia.
Highlights
While sub-microscopic malarial infections are frequent and potentially deleterious during pregnancy, routine molecular detection is still not feasible
This study aimed to assess the performance of this ultrasensitive rapid diagnostic test (uRDT), compared to conventional rapid diagnostic test (RDT) and quantitative polymerase chain-reaction (qPCR), for the detection of P. falciparum malaria in peripheral and placenta blood from pregnant women in Benin, a high malaria-endemic area
The different types and volumes of blood that were used for microscopy, qPCR, RDTs and Histidine Rich Protein 2 (HRP2) level determination are presented in Additional file 1
Summary
While sub-microscopic malarial infections are frequent and potentially deleterious during pregnancy, routine molecular detection is still not feasible. Several studies have evidenced high proportions of sub-microscopic infections—that are not detectable by microscopy because of low parasite densities—among pregnant women [3]. In Benin, this proportion was as high as 25% at the first antenatal care visit in early firsttrimester [4] These infections have been associated with a reduction in birth weight, as well as an increase in low birth weight and maternal anaemia [3, 5, 6], especially those occurring early in pregnancy or in primigravidae [3]. The accurate identification and treatment of women with sub-microscopic infections in the first trimester of pregnancy may be of high clinical relevance considering the high prevalence and significant deleterious effects of these early infections [7,8,9]
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