Poor Diagnostic Performance of a Species-Specific Loop-Mediated Isothermal Amplification (LAMP) Platform for Malaria.

Background: The objective of this study was to assess an in-house loop-mediated isothermal amplification (LAMP) platform for malaria parasite detection and identification on species level.

Methods: LAMP primers specific for the human Plasmodium spp., namely, P. falciparum, P. vivax, P. ovale, P. malariae , and P. knowlesi , as well as genus-specific primers, were tested against a composite gold standard comprising microscopy from thick and thin blood films, commercial genus-specific Meridian illumigene Malaria LAMP, in-house real-time polymerase chain reaction (PCR), and commercial fast-track diagnostics (FTD) Malaria differentiation PCR.

Results: Of the 523 blood samples analyzed, the composite gold standard indicated 243 Plasmodium-species-DNA-containing samples (46.5%). Sensitivity and specificity of the analyzed genus- and species-specific LAMP primers were 71.0%-100.0% and 90.8%-100.0%, respectively. The influence of parasitemia was best documented for P. falciparum -specific LAMP with sensitivity values of 35.5% (22/62) for microscopically negative samples containing P. falciparum DNA, 50% (19/38) for parasitemia ≤50/μL, 84% (21/25) for parasitemia ≤500/μL, and 100% (92/92) for parasitemia >500/μL.

Conclusions: In our hands, performance characteristics of species-specific in-house LAMP for malaria lack reliability required for diagnostic laboratories. The use of the easy-to-apply technique for surveillance purposes may be considered.