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Loop-mediated isothermal amplification for asymptomatic malaria diagnosis in the Peruvian Amazon: technical performance and pilot implementation in challenging field settings

Elisa Serra-Casas 1 ; Paulo Manrique 2 ; Xavier C. Ding 3 ; Gabriel Carrasco-ecobar 4 ; Freddy Alava 2 ; Anthony Gave 2 ; Juan Jose Contreras-Mancilla 5 ; Angel Rosas-Aguirre 6 ; Iveth Gonzalez 7 ; Anna Rosanas-Urgell 1 ; Dionicia Gamboa 8
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BACKGROUND: Loop-mediated isothermal amplification (LAMP) methodology offers an opportunity for point-of-care (POC) molecular detection of asymptomatic malaria infections. However, there is still little evidence on the feasibility of implementing this technique for population screenings in isolated field settings. METHODS: A cross-sectional survey to detect asymptomatic malaria infection recruited 1167 individuals from terrestrial (‘Road’) and hydric (‘Riverine’) communities of the Peruvian Amazon. The performance of LAMP diagnosis, compared to real-time Polymerase Chain Reaction (qPCR) as reference standard, was evaluated in a subgroup of 503 samples. In addition, the operational feasibility of introducing LAMP diagnosis in the mobile screening teams was assessed and complemented with a pilot POC-LAMP implementation in a Riverine community without laboratory infrastructure. RESULTS: The sensitivity and specificity of LAMP assay compared to qPCR was 91.8% (87.7 - 94.9) and 91.9% (87.8 - 95.0) respectively, and the overall accuracy was significantly better among samples collected during Road screenings than in Riverine communities (p≤0.004). LAMP-based diagnostic strategy was successfully implemented within the mobile field-team logistics, while LAMP-POC pilot in the community allowed for a reduction in the turnaround time for case management, from 12-24 hours to less than 5 hours. In Riverine screenings we observed hemolysis of samples that hampered interpretation of the LAMP reaction in these communities. CONCLUSIONS: LAMP-based molecular malaria diagnostics can be used outside of reference laboratories with similar performance as qPCR assays. However, logistical challenges that can influence performance and need to be considered in remote field settings include, among others, environmental conditions and labor-intensiveness in large population screenings.