Diagnostic performance of a Recombinant Polymerase Amplification Test-Lateral Flow (RPA-LF) for cutaneous leishmaniasis in an endemic setting of Colombia.

Alexandra Cossio,Bruno L. Travi,Nancy Gore Saravia,Thomas R. Shelite,María del Mar Castro,Peter C. Melby,Jimena Jojoa,Ruth Mabel Castillo,Lyda Osorio,Philippe Büscher

doi:10.1371/journal.pntd.0009291

Abstract

Control of cutaneous leishmaniasis by public health systems in the Americas relies on case identification and treatment. Point-of-care diagnostics that can be performed by health workers within or near affected communities could effectively bring the health system to the resource-limited sites providing early diagnosis and treatment, reducing morbidity and the burden of disease. A cross-sectional study was undertaken to evaluate the diagnostic test performance of Isothermal Recombinase Polymerase Amplification (RPA) targeting Leishmania kinetoplast DNA, coupled with a lateral flow (LF) immunochromatographic strip, in a field setting and a laboratory reference center. Minimally invasive swab and FTA filter paper samples were obtained by community health workers and highly trained technicians from ulcerated lesions of > 2 weeks' evolution from 118 patients' ≥ 2 years of age in the municipality of Tumaco, Nariño. Extracted DNA was processed by RPA-LF at a reference center or in a primary health facility in the field. Evaluation was based on a composite "gold standard" that included microscopy, culture, biopsy and real-time polymerase chain reaction detection of Leishmania 18S rDNA. Standard of care routine diagnostic tests were explored as comparators. Sensitivity and specificity of RPA-LF in the reference lab scenario were 87% (95%CI 74-94) and 86% (95%CI 74-97), respectively. In the field scenario, the sensitivity was 75% (95%CI 65-84) and specificity 89% (95%CI 78-99). Positive likelihood ratios in both scenarios were higher than 6 while negative likelihood ratios ranged to 0.2-0.3 supporting the usefulness of RPA-LF to rule-in and potentially to rule-out infection. The low complexity requirements of RPA-LF combined with non-invasive sampling support the feasibility of its utilization by community health workers with the goal of strengthening the diagnostic capacity for cutaneous leishmaniasis in Colombia. ClinicalTrials.gov NCT04500873.

Highlights

Cutaneous leishmaniasis (CL) is a recognized public health challenge in the Americas, with an average of 55,000 cases per year between 2001–2018 in 17 countries of the region [1]
Limited access to diagnosis is a critical determinant of the “neglect” that defines the socalled Neglected Tropical Diseases (NTDs) including cutaneous leishmaniasis
Using non-invasive swab and filter paper samples obtained by Community Health Workers, we evaluated the diagnostic performance of an innovative and technically simple molecular test: Isothermal Recombinase Polymerase Amplification (RPA) to detect Leishmania DNA, coupled with a lateral flow (LF) strip to read the results with the naked eye

Summary

Introduction

Cutaneous leishmaniasis (CL) is a recognized public health challenge in the Americas, with an average of 55,000 cases per year between 2001–2018 in 17 countries of the region [1]. Leishmaniasis control efforts rely on case identification and treatment, both of which are challenging in rural areas where access to health services is often scarce. One of the goals of the Pan American Health Organization for control of leishmaniasis in the Americas 2017–2022 is to improve the opportunity and access to diagnosis, treatment, rehabilitation and adequate follow-up of leishmaniasis cases [5]. Control of cutaneous leishmaniasis by public health systems in the Americas relies on case identification and treatment. Point-of-care diagnostics that can be performed by health workers within or near affected communities could effectively bring the health system to the resource-limited sites providing early diagnosis and treatment, reducing morbidity and the burden of disease.

Methods

Results

Conclusion