development and assessment of loop-mediated isothermal amplification (lamp) assay for the diagnosis of human visceral leishmaniasis in iran.

background: parasitological methods for the diagnosis of visceral leishmania-sis (vl) require invasive procedures, so serological and molecular approaches have been developed but are not generally applicable in the field. we evaluated a loop mediated isothermal amplification (lamp) assay using blood from vl pa-tients and compared it to nested pcr. methods: forty-seven subjects with clinical features (fever, hepatosplenomegaly and anemia) were confirmed positive for vl by the direct agglutination test (dat) at titers >3200. forty dat negative individuals from non-endemic areas with no clinical signs or symptoms of vl served as controls. a lamp assay was performed using a set of six primers targeting leishmania infantum kinetoplast dna (kdna) minicircle gene under isothermal (64 °c) conditions. for nested pcr we used primers targeting the kdna minicircle gene. results: the lamp assay provided a detection limit of 1 parasite in 1 ml of peripheral blood and detected l. infantum dna in 44 of 47 dat-confirmed vl cases, with diagnostic sensitivity of 93.6% (95% ci). no l. infantum dna was amplified in controls, indicating a specificity of 100%. the nested pcr yielded sensitivity of 96% (95% ci) and a specificity of 100% (95% ci). conclusion: the lamp assay gave results similar to those of nested pcr but in a shorter time. the lamp method is simple; requires no sophisticated equip-ment; has a short reaction time; and results, indicated by turbidity of the reaction mixture, are observable with the naked eye.