Application of loop mediated isothermal amplification to detect schistosoma mansoni DNA in wild snails from Mbita sub-county, Kenya

Abstract

Background: Studies show that wild snail schistosomal infection rates correspond well to the prevalence of human infection and that in the diagnosis of schistosomiasis, Deoxy-Ribonucleic Acid (DNA) detection by Polymerase Chain Reaction (PCR) and Loop-Mediated Isothermal Amplification (LAMP) are superior to snail cercariometry and microscopy. PCR and LAMP are expensive and high-level laboratory tests whereas schistosomiasis is prevalent in rural resource-poor environments.
Objective: To develop LAMP for use in detecting Schistosoma mansoni in snails in resource-poor field settings.
Design, Methods and Materials: In a laboratory experiment, field snails were tested for S. mansoni DNA using LAMP and PCR. LAMP employed primers designed from parasite tandem repeat sequences. The amplicon was analyzed using a visible dye which makes the test suitable for resource-poor settings that often lack sophisticated detection equipment.
Setting and Study Subjects: The experiment was done in the laboratory of the Institute of Tropical Medicine in Nagasaki. 131 wild snails of the Biomphalaria spp. harvested in Mbita Sub-County were infected, dried and stored. 29 were randomly selected for the experiment.
Outcome Measures: An amplicon detectable by both LAMP and PCR was considered a positive outcome.
Results: 7 specimens were positive. LAMP was sensitive up to a day-old parasite. A naked eye detectable dye was successfully used to aid detection of the amplicon.
Conclusions and Recommendations: LAMP detected one-day-old infections in wild snails, and this could be visualized with the naked eye which made the test suitable for further development for use in field laboratories