Performance of malaria rapid diagnostic test, microscopy, polymerase chain reaction, and histopathology to diagnose malaria among pregnant and parturient women using peripheral, placental, and cord blood, and placental biopsy in Majang Zone of Gambella Region, Southwest Ethiopia

Abstract

Background: Accurate, reliable, and timely diagnosis is essential for mitigating malaria in pregnancy (MiP) and its adverse outcomes. This study aimed to evaluate the accuracy of malaria diagnostic tests for detecting Plasmodium infection in peripheral, placental, and cord blood and placental biopsy in the Majang Zone of Gambella Region, Southwest Ethiopia.

Methods: A cross-sectional study involving 640 (460 pregnant and 180 parturient) women visiting five public health facilities for antenatal care and delivery services in Majang Zone was conducted from November 2022 to March 2023. Peripheral, placental, and cord blood were collected to detect Plasmodium infection by rapid diagnostic test (RDT), microscopy, and quantitative Polymerase Chain Reaction (qPCR). Placental biopsy was collected for placental malaria (PM) diagnosis by histopathology. Performance indices, Kappa Coefficient, and Receiver Operating Characteristic were determined using Statistical Package for Social Science Version 26.0, Microsoft Excel Version 19.0, and Stata Version 17.0.

Results: One thousand blood (640 peripheral, 180 placental, and 180 cord) and 180 placental biopsy specimens collected from pregnant and parturient women were analysed in this study. Malaria positivity rate among pregnant and parturient women was 21.1% and 28.9%, respectively. Considering peripheral blood qPCR as a reference, the sensitivity, specificity, accuracy, and agreement of RDT were (63.5%, 93.0%, 0.807, and 0.683), and microscopy were (73.1%, 98.0%, 0.855, and 0.764) to detect Plasmodium infection in combined peripheral blood of pregnant and parturient women, respectively. Considering placental blood qPCR as a reference, the sensitivity, specificity, accuracy, and agreement of RDT were (56.3%, 95.5%, 0.759, and 0.574), microscopy were (81.3%, 97.7%, 0.895, and 0.822), and histopathology (87.5%, 100.0%, 0.892, and 0.911) to detect Plasmodium infection in placental blood of parturient women, respectively. Considering placental histopathology a as reference, the sensitivity, specificity, accuracy, and agreement of RDT were (56.8%, 97.1%, 0.753, and 0.609), microscopy were (68.2%, 98.5%, 0.918, and 0.735), and qPCR (100.0%, 95.7%, 0.978, and 0.911) to detect Plasmodium infection in placental blood of parturient women, respectively.

Conclusion: Diagnostic performance of RDT and microscopy was sub-optimal to detect Plasmodium infection among pregnant and parturient women. More sensitive diagnostic tests are needed to mitigate MiP.

Keywords: Diagnostic test accuracy; Ethiopia; Gambella; Histopathology; Kappa; Majang; Malaria in pregnancy; Microscopy; Placental malaria; QPCR; RDT; Receiver operating characteristic; Sensitivity.

Fig. 1

Flowchart showing the process of specimen collection and laboratory tests employed to evaluate the diagnostic accuracy of malaria diagnostic tests in detecting Plasmodium infection among pregnant and parturient women in Majang Zone of Gambella Region, Southwest Ethiopia, November 2022–March 2023

Fig. 2

Venn diagram showing malaria positive results by RDT, microscopy, and qPCR in peripheral blood of pregnant women in Majang Zone of Gambella Region, Southwest Ethiopia, November 2022–March 2023 (n = 142)

Fig. 3

Venn diagram showing malaria positive results by RDT, microscopy, qPCR and histopathology (B only) in peripheral blood (A), placental samples (B), placental blood (C), and cord blood (D) of parturient women in Majang Zone of Gambella Region, Southwest Ethiopia, November 2022–March 2023 (n = 60)

Fig. 4

Venn diagram showing malaria positive results by RDT, microscopy, and qPCR in peripheral blood of pregnant women and parturient women in Majang Zone of Gambella Region, Southwest Ethiopia, November 2022–March 2023 (n = 202)

Fig. 5

ROC curve showing the diagnostic performance of index tests to detect Plasmodium infection among pregnant women using peripheral blood qPCR as reference in Majang Zone of Gambella Region, Southwest Ethiopia, November 2022–March 2023 (n = 142)

Fig. 6

ROC curve showing the diagnostic performance of index tests to detect Plasmodium infection among parturient women using peripheral blood qPCR as reference in Majang Zone of Gambella Region, Southwest Ethiopia, November 2022–March 2023 (n = 60)

Fig. 7

ROC curve showing the diagnostic performance of index tests to detect Plasmodium infection among parturient women using placental blood qPCR as reference in Majang Zone of Gambella Region, Southwest Ethiopia, November 2022–March 2023 (n = 60)

Fig. 8

ROC curve showing the diagnostic performance of index tests to detect Plasmodium infection among parturient women using placental histopathology as reference in Majang Zone of Gambella Region, Southwest Ethiopia, November 2022–March 2023 (n = 180)

Fig. 9

ROC curve showing the diagnostic performance of index tests to detect Plasmodium infection among pregnant and parturient women using peripheral blood qPCR as reference in Majang Zone of Gambella Region, Southwest Ethiopia, November 2022–March 2023 (n = 202)