Detection of Plasmodium Infection by the illumigene Malaria Assay Compared to Reference Microscopy and Real-Time PCR

Abstract

Malaria is one of the leading causes of infectious disease in travelers returning from the tropics. The diagnosis of malaria is typically performed by examining Giemsa-stained thick and thin peripheral blood smears, which is time consuming, labor intensive, and requires high levels of proficiency. Alternatively, loop-mediated isothermal amplification (LAMP) is a new molecular method, which is rapid, sensitive, and requires less capital equipment and technological training. We conducted a retrospective study comparing two formats of a commercial LAMP assay (Meridian gene malaria [M] and malaria Plus [MP]) versus reference microscopy on archived blood specimens ( = 140) obtained from unique returning travelers suspected of having malaria. Discrepant results were resolved by either repeat testing or a laboratory developed ultrasensitive real-time PCR method. On initial testing, the Meridian gene M and MP kits had sensitivities of 97.3% (95% confidence interval [CI], 90.7 to 99.7%) and 100.0% (95.1 to 100.0%) and specificities of 93.8% (84.8 to 98.3%) and 91.5% (81.3 to 97.2%), respectively, versus reference microscopy. We project a significant cost reduction in low prevalence settings where malaria is not endemic with LAMP-based malaria screening given the excellent negative predictive value achieved with LAMP.

Performance evaluation of different strategies based on microscopy techniques, rapid diagnostic test and molecular loop-mediated isothermal amplification assay for the diagnosis of imported malaria

“…Nevertheless, neither RDT nor LAMP should be used on its own; they need to be combined with another technique such as TnS to allow for species identification, parasitaemia assessment and nonfalciparum Plasmodium detection for RDT. However, given LAMP's high negative predictive value for all species, this technology could be used as a single test for Plasmodium detection, as already suggested by others [24,25,28,29]. In the event of a positive result, TnS (with or without RDT) would be required to determine the Plasmodium species and parasitaemia.…”

A Novel Single-Nucleotide Polymorphism Loop Mediated Isothermal Amplification Assay for Detection of Artemisinin-Resistant Plasmodium falciparum Malaria

“…Of note, this type of equipment can be powered by lithium ion battery (our unpublished observations). Optimization of a simplified extraction method is required akin to the gravity flow columns used in certain commercial LAMP kits so that centrifugation can be avoided [ 35 ]. The best performance characteristics of the assay were achieved with a prior knowledge of parasite density.…”

Diagnostic accuracy of loop-mediated isothermal amplification (LAMP) for screening patients with imported malaria in a non-endemic setting

“…Sensitivity and specificity of LAMP compared to microscopy have already been shown to be 98% and 97%, respectively from a meta-analysis of molecular methods for malaria diagnosis [ 24 ]. A recent study from Canada [ 25 ] has shown a sensitivity of 100.0% [95.1- 100.0%] and specificity of 91.5% [81.3 − 97.2%] versus reference microscopy. Similar remarkable results were obtained in this study (sensitivity of 100% [95.55 to 100%] and specificity of 93.64% [89.55 to 96.48%] versus microscopy.…”