Combination of PURE-DNA extraction and LAMP-DNA amplification methods for accurate malaria diagnosis on dried blood spots

Abstract

BackgroundMalaria is one of the most important parasitic infectious diseases for which almost half of the world’s population is at risk. Although several diagnostic methods are now available to detect the infection, more sensitive and applicable tests are still required in the field. The loop-mediated isothermal amplification (LAMP) method is a DNA amplification tool in which the DNA amplification can be achieved by incubation at a stable temperature. A malaria detection kit based on this methodology has already been commercialized and is being used in some countries. The kit includes two reaction tubes: one targeting the common Plasmodium genus (Pan tube) and the other specifically targeting Plasmodium falciparum (Pf tube). In parallel, a simple DNA extraction method, the procedure for ultra rapid extraction (PURE), which can produce a DNA solution suitable for the LAMP reaction without the use of a centrifuge, has also become available. In this study, the sensitivity of the combination of the PURE and LAMP methods (PURE–LAMP) was evaluated with archived dried clinical blood samples of imported malaria cases, including P. falciparum, Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae.ResultsUsing a nested PCR as the reference, 117 samples including 46 P. falciparum, 7 P. vivax, 9 P. ovale, 4 P. malariae, and 51 negative cases were tested. The PURE–LAMP Pan correctly identified 64 of the 66 positives and the 51 negatives. Among the Pan-positive samples 45 P. falciparum were also detected with the PURE–LAMP Pf. The PURE–LAMP Pan and PURE–LAMP Pf had respective sensitivities of 96.96% (95% CI 89.47–99.63) and 97.82% (95% CI 88.47–99.94) and common specificity of 1.ConclusionThe PURE–LAMP system is accurate when used with dried blood spots and extendable to the field.Electronic supplementary materialThe online version of this article (10.1186/s12936-018-2527-7) contains supplementary material, which is available to authorized users.

Evaluation of the colorimetric malachite green loop-mediated isothermal amplification (MG-LAMP) assay for the detection of malaria species at two different health facilities in a malaria endemic area of western Kenya

“…The sensitivity of MG-LAMP was higher than RDT and microscopy, but a lower specificity at the two health facilities. These results are consistent with previous studies showing the higher sensitivity but lower specificity of MG-LAMP compared to microscopy and RDT [ 37 , 39 , 40 ]. There are many factors which could affect the sensitivity of different diagnostic methods including sample collection method and preparation, efficiency of nucleic acid extraction procedure, amount of blood, amount of template used in the reaction, copy number of target sequence and the buffers, enzymes and other materials used [ 12 ].…”

Evaluation of Loop Mediated Isothermal Amplification (LAMP) for Diagnosis of Plasmodium falciparum in Wad Medani City, Gezira State, Sudan

“…Similar findings were also reported by other authors elsewhere [10,12,18]. However, Vincent et al, [19]; Pöschl et al, [20]; Sirichaisinthop et al, [21] reported a higher specificity (100%) when compared to our results. Moreover, Weighted Kappa (0.86) is higher when compared with finding of Poblete et al, [22] (Weighted Kappa = 0.84).…”

Performance of PURE-LAMP to Detect Declining Prevalence of Malaria in Haiti

“…Our previous evaluation of the PURE-LAMP method with dried blood spots conducted with imported cases in a non-endemic setting showed a sensitivity over 96% and specificity of 100% [16]. A review of previously reported evaluations of the Loopamp™ MALARIA Pan/Pf Detection Kit with > 35 samples per group in diverse settings showed sensitivity in a range from about 90% up to 100% and specificity from about 85-100% [11][12][13][14][15][16]. The results of the present study also lie within these ranges.…”

“…Among the different malaria LAMP assays developed, two commercial kits have become available: the Loopamp™ MALARIA Pan/Pf Detection Kit (Eiken Chemical, Tokyo, Japan) [11][12][13][14][15][16][17][18][19][20][21] and the Illumigene Malaria LAMP (Meridian Bioscience Inc., Cincinnati, OH, USA) [22,23]. The Loopamp™ MALARIA Pan/Pf Detection Kit has been evaluated with a significant number of samples in various studies conducted in both endemic [12-15, 20, 21] and non-endemic settings [11,16], using whole blood [11][12][13] or dried blood spots [15,16], and coupled with diverse DNA extraction methods. One of these methods is the procedure for ultra-rapid extraction (PURE), a quick and simple DNA extraction method, also developed by Eiken Chemical to prepare DNA solution suitable for the LAMP reaction.…”