Head-to-head evaluation of a commercial real-time PCR assay targeting plasmodial species causing human malaria against a composite reference standard

Background: The investigation was conducted to evaluate a robust commercial multiplexed species- or species complex-specific real-time PCR assay for human malaria applicable with mobile cyclers. Methods: A well-characterized sample set of blood samples from travelers with high pre-test probability of being infected with plasmodial species was assessed with the Plasmodium qPCR panel (Bioeksen, Istanbul, Turkey) against a composite reference standard comprising microscopy following the protocols by World Health Organization in combination with four nucleic acid amplification tests for malaria. Results: From 1,020 included samples, composite reference standard testing identified 248 (24.3%) as positive for plasmodial DNA, comprising 217x Plasmodium falciparum, 14x Plasmodium vivax, 8x Plasmodium ovale complex, 6x Plasmodium malariae and 3 samples containing DNA of both P. falciparum and P. vivax. Diagnostic accuracy of the evaluated PCR in terms of sensitivity and specificity was 96.8% (240/248) and 99.5% (768/772). The resulting positive and negative predictive values were 98.4% (240/244) and 99.0% (768/776). False-negative results were associated with either submicroscopic parasitemia or parasitemia at the threshold of microscopic detection. Conclusion: The assessed multiplex real-time PCR assay showed similar performance characteristics like comparable diagnostic assays and thus proved to be suitable for the differentiation of plasmodia in the non-endemic setting.