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J Clin Microbiol. 2018 Jun 25;56(7). pii: e00386-18. doi: 10.1128/JCM.00386-18. Print 2018 Jul.

Development and Evaluation of a Novel Loop-Mediated Isothermal Amplification Assay for Diagnosis of Cutaneous and Visceral Leishmaniasis.

Author information

1
Research Centre for Drugs and Diagnostics, Parasitology Department, Liverpool School of Tropical Medicine, Liverpool, United Kingdom Emily.adams@lstmed.ac.uk.
2
Academic Medical Centre, Department of Medical Microbiology, Parasitology Unit, Amsterdam, The Netherlands.
3
Centro Internacional de Entrenamiento e Investigaciones Médicas, CIDEIM, Cali, Colombia.
4
Universidad Icesi, Cali, Colombia.
5
University of Gondar, Gondar, Ethiopia.
6
Eiken Chemical Company, Tokyo, Japan.
7
Parasite Genomics, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom.
8
University of Addis Ababa, School of Medicine, Addis Ababa, Ethiopia.
9
Foundation for Innovative New Diagnostics, Geneva, Switzerland.

Abstract

A novel pan-Leishmania loop-mediated isothermal amplification (LAMP) assay for the diagnosis of cutaneous and visceral leishmaniasis (CL and VL) that can be used in near-patient settings was developed. Primers were designed based on the 18S ribosomal DNA (rDNA) and the conserved region of minicircle kinetoplast DNA (kDNA), selected on the basis of high copy number. LAMP assays were evaluated for CL diagnosis in a prospective cohort trial of 105 patients in southwest Colombia. Lesion swab samples from CL suspects were collected and were tested using the LAMP assay, and the results were compared to those of a composite reference of microscopy and/or culture in order to calculate diagnostic accuracy. LAMP assays were tested on samples (including whole blood, peripheral blood mononuclear cells, and buffy coat) from 50 suspected VL patients from Ethiopia. Diagnostic accuracy was calculated against a reference standard of microscopy of splenic or bone marrow aspirates. To calculate analytical specificity, 100 clinical samples and isolates from fever-causing pathogens, including malaria parasites, arboviruses, and bacteria, were tested. We found that the LAMP assay had a sensitivity of 95% (95% confidence interval [CI], 87.2% to 98.5%) and a specificity of 86% (95% CI, 67.3% to 95.9%) for the diagnosis of CL. With VL suspects, the sensitivity of the LAMP assay was 92% (95% CI, 74.9% to 99.1%) and its specificity was 100% (95% CI, 85.8% to 100%) in whole blood. For CL, the LAMP assay is a sensitive tool for diagnosis and requires less equipment, time, and expertise than alternative CL diagnostics. For VL, the LAMP assay using a minimally invasive sample is more sensitive than the gold standard. Analytical specificity was 100%.

KEYWORDS:

LAMP; Leishmania; cutaneous; diagnostics; visceral

PMID:
29695527
PMCID:
PMC6018344
DOI:
10.1128/JCM.00386-18
[Indexed for MEDLINE]
Free PMC Article

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