Direct detection of falciparum and non-falciparum malaria DNA from a drop of blood with high sensitivity by the dried-LAMP system

Background: because of the low sensitivity of conventional rapid diagnostic tests (rdts) for malaria infections,the actual prevalence of the diseases,especially those caused by non-plasmodium falciparum (non-pf) species,in asymptomatic populations remain less defined in countries lacking in well-equipped facilities for accurate diagnoses. our direct blood dry lamp system (czc-lamp) was applied to the diagnosis of malaria as simple,rapid and highly sensitive method as an alternative for conventional rdts in malaria endemic areas where laboratory resources are limited. results: lamp primer sets for mitochondria dnas of plasmodium falciparum (pf) and human-infective species other than pf (non-pf; p. vivax,p. ovale,p. malariae) were designed and tested by using human blood dna samples from 74 residents from a malaria endemic area in eastern zambia. these malaria dry-lamps were optimized for field or point-of-care operations,and evaluated in the field at a malaria endemic area in zambia with 96 human blood samples. to determine the sensitivities and specificities,results obtained by the on-site lamp diagnosis were compared with those by the nested pcr and nucleotide sequencing of its product. the dry lamps showed the sensitivities of 89.7% for pf and 85.7% for non-pf,and the specificities of 97.2% for pf and 100% for non-pf,with purified blood dna samples. the direct blood lamp diagnostic methods,in which 1 μl of anticoagulated blood were used as the template,showed the sensitivities of 98.1% for pf,92.1% for non-pf,and the specificities of 98.1% for pf,100% for non-pf. the prevalences of p. falciparum,p. malariae and p. ovale in the surveyed area were 52.4,25.3 and 10.6%,respectively,indicating high prevalence of asymptomatic carriers in endemic areas in zambia. conclusions: we have developed new field-applicable malaria diagnostic tests. the malaria czc-lamps showed high sensitivity and specificity to both p. falciparum and non-p. falciparum. these malaria czc-lamps provide new means for rapid,sensitive and reliable point-of-care diagnosis for low-density malaria infections,and are expected to help update current knowledge of malaria epidemiology,and can contribute to the elimination of malaria from endemic areas. © 2017 the author(s).