Clinical features of cutaneous leishmaniasis in Sri Lanka and molecular identification of L. donovani as the cause

Abstract

BACKGROUND: Cutaneous leishmaniasis (CL) is a newly established disease in Sri Lanka with over 1500 locally acquired cases reported since year 2001. OBJECTIVES: To study the clinical profile, associated risk factors and genetic analysis of the causative parasite of CL in Sri Lanka. METHODOLOGY: Clinical evaluation was carried out on patients who visited the Department of Parasitology, Faculty of Medicine, Colombo for diagnosis using a pre-tested questionnaire. Light microscopy and/or PCR were performed on lesion material to confirm diagnosis. Formol gel test (FGT) was done on all patients. The causative species was identified by sequencing of the partial 6PGDH gene, followed by microsatellite analysis to study the phylogenetic relationships. RESULTS: There were 401 patients (78.9% males, out of which 57.4% were soldiers) with at least 549 lesions. Most infections were acquired in Northern (55.7%) or Southern (39.3%) Sri Lanka. Several lesion types were noted: papules 23.4%, nodules 25.4%, ulcerating nodules 19.6%, ulcers 23.7%, plaques 6.4% and other 1.7%. Nodules with 5–9 months duration had the highest parasite positivity (n = 100, 75.5%). Sporotrichoid spread (n = 44, 11.9%), satellite lesions (n = 35, 8.9%) and lymphatic spread (n = 109, 27.7%) were commonly observed. No patients had visceral features and the FGT was negative in all subjects. Male sex, 20–40 years of age and over 5 hours/day spent outdoors were identified as risk factors, but not household clustering. The causative species was identified as L. donovani, belonging to a distinct genetic group within that complex. CONCLUSIONS: A dermotrophic variant of L. donovani causes cutaneous leishmaniasis in Sri Lanka. The ability of the local Leishmania parasite to visceralize, self heal or develop drug resistance is yet to be determined. In spite of the generally accepted anthroponotic nature of L donovani, in this study favours zoonotic transmission of the local species. Acknowledgements: Mr. RL Ihalamulla, Mr. S Jayasinghe for technical assistance. Financial support for this study was from Sri Lanka National Science Foundation and the Commonwealth Scholarship Association. © 2008 Elsevier Inc.