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.