Introduction of Recombinase Polymerase Amplification assay based mobile suitcase laboratory as a point of need tool to diagnose cutaneous leishmaniasis in Sri Lanka

Abstract

INTRODUCTION AND OBJECTIVES: Cutaneous leishmaniasis (CL) caused by the vector-borne protozoan parasite is now endemic in Sri Lanka. Microscopy of Giemsa stained slit skin smears (SSS), lesion aspirates or scrapings for the presence of amastigotes, is widely used for laboratory confirmation of CL, although the reported sensitivity is low. Facilities for more sensitive culture and molecular techniques are available only in reference laboratories. A newly developed, Recombinase Polymerase Amplification (RPA) assay based Mobile Suitcase Laboratory (MSL) is a promising, molecular point of care test with high sensitivity and specificity for diagnosis of both post-kala• azar dermal leishmaniasis and visceral leishmaniasis. Objective was to assess RPA based MSL as a point of need tool to diagnose CL in Sri Lanka.METHODS: Twenty seven army personnel at Mullaitivu Army camp clinically suspected of having CL were recruited for this pilot study. Two slit skin smears and two punch biopsy specimens were obtained from each of them. Slit skin smears were stained with Giemsa in the field and examined for the presence of amastigotes and RPA was carried out at the point of collection. PCR was performed at the Parasitology Department, Sri Jayewardenepura University. RESULTS: Fifteen patients were confirmed by PCR as having CL and 14 of them were also positive by RPA based MSL conducted in the field (93.33% sensitivity). Only 3/15 were positive with microscopy of SSS (20% sensitivity). CONCLUSION: This pilot study shows RPA based MSL as a promising tool to diagnose CL at point of need.