Comparative Diagnosis of Malaria Infections by Microscopy, Nested PCR, and LAMP in Northern Thailand

Abstract

Abstract. Three methods, microscopy, nested polymerase chain reaction (nPCR), and loop-mediated isothermal amplification (LAMP) have been applied for malaria diagnosis in 105 human blood samples collected in Northern Thailand. Only Plasmodium falciparum and Plasmodium vivax infections were detected. A total number of 57 positives (54%) could be detected for P. falciparum and 25 (24%) for P. vivax when all samples that were positive in any of the three methods are counted together. The nPCR was used as a reference standard for comparison with the other methods, microscopy and LAMP. The sensitivity of LAMP for P. falciparum was 100%. All nPCR-negative samples for P. falciparum were also negative by both microscopy and LAMP (specificity, 100%). For diagnosis of P. vivax , microscopy detected 15 of 23 nPCR-positive samples (sensitivity, 65%). LAMP detected 22 of 23 nPCR-positives (sensitivity, 96%). Among the 82 nPCR-negative samples microscopy detected two samples (specificity, 98%). All 82 nPCR-negative were also negative by the LAMP method (specificity, 100%). Both Plasmodium genus-and species-specific LAMP primer sets yielded the same results in all samples. There were no significant differences in the prevalence detected by each method. We assume that LAMP was as reliable as nPCR and more reliable than microscopy in the detection of Plasmodium DNA tested in the examined Thai field blood samples. This study further validates LAMP as an alternative molecular diagnostic tool, which can be used in the diagnosis of early infections of malaria cases and together with nPCR can also be used as supplementary methods for clinical and epidemiological use.

Performance of loop-mediated isothermal amplification (LAMP) for the diagnosis of malaria among malaria suspected pregnant women in Northwest Ethiopia

“…Loop-mediated isothermal amplification (LAMP) is a simpler molecular procedure and better alternative for the field than nPCR [18, 19]. LAMP has many operational advantages over PCR including: (1) the acceptability of a crude sample preparation; (2) minimal capital equipment requirements; (3) rapid time to obtain a result; (4) lower cost; and (5) technically less complex than PCR [20].…”

Molecular diagnosis of infections and resistance in veterinary and human parasites

“…A change from polymerase chain reaction to loop-mediated isothermal amplication (LAMP) has certain advantages because temperature cycling is not necessary. A number of other amplification systems which do not require temperature cycling have also been developed (Compton, 1991;Guatelli et al, 1990;Walker et al, 1992a,b;Abramowitz, 1996;Vrana, 1996) and applied to parasite detection (Matovu et al, 2010a), but LAMP is currently the most widely used alternative to PCR (Kuboki et al, 2003;Thekisoe et al, 2005;Alhassan et al, 2007;Han et al, 2007;Karanis et al, 2007;Guan et al, 2008;Njiru et al, 2008a,b;Peyrefitte et al, 2008;Aonuma et al, 2009;Liang et al, 2009;Nkouawa et al, 2009;Takagi et al, 2009;Abbasi et al, 2010;Adams et al, 2010;Iseki et al, 2010;Kumagai et al, 2010;Lau et al, 2010;Matovu et al, 2010b;Ndung'u et al, 2010;Polley et al, 2010;Poschl et al, 2010;Thekisoe et al, 2010;Wang et al, 2010;Njiru, 2011). LAMP and these other alternatives to PCR are still based on enzymatic reactions however, so the transport and storage of reagents at below room temperature is a requirement and a challenge for field application.…”

Novel techniques and future directions in molecular diagnosis of malaria in resource-limited settings

“…Loop-mediated isothermal amplification (LAMP) is one isothermal technique that has been mostly developed and used for detection of Plasmodium spp. LAMP assays have comparable sensitivity and specificity as PCR for malaria parasite detection [22][23][24]. Novel targets within the Plasmodium parasite are now being optimized for increased sensitivity to detect lowdensity malaria infections.…”