Tamir Zemenu, Animut Abebe, Dugassa Sisay, Gebresilassie Araya, Belachew Mahlet, Abera Adugna, Erko Berhanu
Department of Medical Laboratory Sciences, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia.
Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
Malar J. 2025 Jan 20;24(1):19. doi: 10.1186/s12936-025-05256-2.
Low malaria parasitaemia is a diagnostic challenge in pregnancy, leading to false negative microscopy and rapid diagnostic test (RDT) results. However, these submicroscopic or subpatent infections could cause adverse pregnancy outcomes. Thus, evaluating the diagnostic performance of microscopy, RDT, and multiplex qPCR in pregnancy is vital for informed decisions.
A total of 835 peripheral blood and 372 placental blood samples were collected from 835 pregnant women attending first antenatal care or admitted for delivery at selected health facilities in northwest Ethiopia between November 2021 and July 2022. In multiplex qPCR, all microscopy and/or RDT positive samples were extracted and amplified individually, whereas all samples negative by both RDT and microscopy were extracted after pooling ten samples together and tested for Plasmodium genus. The diagnostic performance of microscopy, RDT, and multiplex qPCR in pregnancy was compared and evaluated against each other.
Using multiplex qPCR as a reference test, microscopy had a sensitivity of 73.8% (95% confidence interval (CI): 65.9-80.7) and 62.2% (95% CI: 46.5-76.2) to detect Plasmodium parasites in peripheral and placental blood samples, respectively, with a 100% (95% CI: 98.9-100) specificity in both samples. Similarly, the RDT had a sensitivity of 67.6% (95% CI: 59.3-75.1) and a specificity of 96.5% (95% CI: 94.9-97.8) for Plasmodium infection diagnosis in peripheral blood and a sensitivity of 62.2% (95% CI: 46.5-76.2) and a specificity of 98.8% (95% CI: 96.9-99.7) in placental blood samples. Considering microscopy as a reference test, multiplex qPCR showed a sensitivity of 100% (95% CI: 96.6-100) and a specificity of 94.8% (95% CI: 93.0-96.3) to diagnose Plasmodium infections in both peripheral and placental blood samples. Pooled multiplex qPCR detected 34 peripheral and 12 placental blood Plasmodium infections from microscopy and RDT negative samples. The pooled assay obviated about half of the reactions and its testing costs. Microscopy showed almost perfect agreement (κ = 0.823) with multiplex qPCR for detecting malaria parasites in pregnancy, whereas the RDT showed a substantial agreement (κ = 0.684).
Multiplex qPCR had a better performance for Plasmodium infection diagnosis in pregnancy compared to microscopy and RDT. Pooled multiplex qPCR could be a sensitive and resource-efficient strategy for epidemiological surveillance of Plasmodium infections in pregnancy.
低疟原虫血症是孕期诊断的一项挑战，会导致显微镜检查和快速诊断检测（RDT）出现假阴性结果。然而，这些亚显微或亚临床感染可能会导致不良妊娠结局。因此，评估显微镜检查、RDT和多重定量聚合酶链反应（qPCR）在孕期的诊断性能对于做出明智决策至关重要。
2021年11月至2022年7月期间，从埃塞俄比亚西北部选定卫生设施接受首次产前检查或入院分娩的835名孕妇中，共采集了835份外周血样本和372份胎盘血样本。在多重qPCR中，所有显微镜检查和/或RDT阳性样本单独提取并扩增，而RDT和显微镜检查均为阴性的所有样本在将十个样本合并在一起后提取，并检测疟原虫属。相互比较并评估了显微镜检查、RDT和多重qPCR在孕期的诊断性能。
以多重qPCR作为参考检测方法，显微镜检查在检测外周血和胎盘血样本中的疟原虫时，敏感性分别为73.8%（95%置信区间（CI）：65.9 - 80.7）和62.2%（95%CI：46.5 - 76.2），两种样本的特异性均为100%（95%CI：98.9 - 100）。同样，RDT诊断外周血疟原虫感染的敏感性为67.6%（95%CI：59.3 - 75.1），特异性为96.5%（95%CI：94.9 - 97.8）；在胎盘血样本中，敏感性为62.2%（95%CI：46.5 - 76.2），特异性为98.8%（95%CI：96.9 - 99.7）。以显微镜检查作为参考检测方法，多重qPCR诊断外周血和胎盘血样本中疟原虫感染的敏感性为100%（95%CI：96.6 - 100），特异性为94.8%（95%CI：93.0 - 96.3）。合并的多重qPCR从显微镜检查和RDT阴性样本中检测到34例外周血和12例胎盘血疟原虫感染。合并检测减少了约一半的反应及其检测成本。在孕期检测疟原虫方面，显微镜检查与多重qPCR显示出几乎完美的一致性（κ = 0.823），而RDT显示出实质性一致性（κ = 0.684）。
与显微镜检查和RDT相比，多重qPCR在孕期疟原虫感染诊断方面表现更佳。合并的多重qPCR可能是孕期疟原虫感染流行病学监测的一种敏感且资源高效的策略。
