Risk Factor Analysis of Cutaneous Leishmaniasis in Sri Lanka through a Nationwide Survey.

Leishmaniasis in Sri Lanka was first reported in the early 1990s. Cutaneous leishmaniasis (CL) cases have markedly increased in recent years, demanding due attention from health authorities. The spatial distribution of CL is not homogeneous. This case-control study investigated factors that may contribute to this heterogeneous distribution through a nationwide study. Information on sociodemographic, economic, and environmental characteristics was collected from study participants (cases, n = 303; controls, n = 2,762). All individuals were followed up for 3 years, and signs of CL or associated complications were recorded. Differences in possible risk factors between cases and controls were analyzed. Individuals <18 years old, electricity supply, spending >2 hours outdoors, visiting jungles/water bodies, and living near CL patients were identified as risk factors. Household members of 1.3% of cases, 2.3% of controls residing within a perimeter of 500 m from a patient, and 0.8% of controls living beyond 2 km from a case developed CL. Thus, CL in Sri Lanka appears intertwined with living environment and host behavior. Common environmental factors may be responsible for the higher risk of CL in individuals living in close proximity to CL patients. This may at least partly explain the clustering of CL cases in selected areas of the country.

Distribution and Seasonal Variation of Phlebotomus and Sergentomyia Sand Fly Populations in Bhutan.

Leishmaniasis is considered one of the neglected tropical diseases in the world. Although Bhutan is a member of the visceral leishmaniasis elimination consortium in South Asia, not much attention has been accorded to the disease because of its low incidence. The vector that transmits Leishmania remains poorly understood. In this backdrop, sand-fly surveys were regularly conducted at multiple sites where leishmaniasis cases have been reported in Bhutan. Collections were made using CDC light traps and cattle-baited net traps in 15 villages from February 2019 to May 2022. Six species of Phlebotomus and four species of Sergentomyia were identified from these sites that included two Phlebotomus and three Sergentomyia species discovered for the first time in Bhutan. Sand-fly density varied significantly from village to village, and it showed strong seasonality with peak numbers collected from June to October and almost zero from December to February. Overall, sand-fly density was highest in the basements of the houses and were higher outdoors than indoors. Cattle-baited net traps collected few sand flies during the surveillance period. This work constituted the first systematic sand-fly population surveillance conducted in Bhutan and will provide a baseline for future vector ecology and Leishmania epidemiological studies.

Efforts toward the Elimination of Visceral Leishmaniasis in South Asia: A Review of Progress in Bhutan.

Leishmaniases are a group of diseases under the category of neglected tropical diseases targeted for global elimination. However, they continue to pose major clinical and public health problems, especially among those living in poor socioeconomic conditions. Here, we summarize leishmaniasis elimination efforts in Bhutan. Between 1994 and 2022, Bhutan recorded 54 cases of leishmaniasis across 14 of its 20 districts. There are seven species of Phlebotomus and three species of Sergentomyia sand flies documented in the country. At a subnational level, all endemic districts recorded a visceral leishmaniasis annual incidence <1 per 10,000 population, meeting the regional elimination targets. Serological testing with ELISA and molecular testing with polymerase chain reaction were established at the Royal Center for Disease Control in 2022. A leishmaniasis prevention and management guideline was adopted in 2023 to aid clinicians in diagnosis and management. Active and passive case surveillance was integrated with the national infectious disease early warning and response system. Risk-based entomological surveillance and control have also been prioritized. Climate change may play a major role in rendering districts in the temperate zone favorable for vector proliferation. The country's medical university introduced a diploma course in medical entomology in 2023 to augment the human resources needed for vector surveillance efforts. However, leishmaniasis elimination lacks dedicated programmatic management amid competing priorities for resources against other infectious diseases. Leishmaniasis elimination requires a targeted and programmatic approach in Bhutan, including cross-border collaborative efforts with neighboring Indian states. Bhutan remains highly committed to achieving leishmaniasis elimination targets.

Next-generation vaccines for tropical infectious diseases.

Tropical infectious diseases inflict an unacceptable burden of disease on humans living in developing countries. Although anti-pathogenic drugs have been widely used, they carry a constant threat of selecting for resistance. Vaccines offer a promising means by which to enhance the global control of tropical infectious diseases; however, these have been difficult to develop, mostly because of the complex nature of the pathogen lifecycles. Here, we present recently developed vaccine candidates for five tropical infectious diseases in the form of a catalog that have either entered clinical trials or have been licensed for use. We deliberate on recently licensed dengue vaccines, provide evidence why combination vaccination could have a synergistic impact on schistosomiasis, critically appraise the value of typhoid conjugate vaccines, and discuss the potential of vaccines in the efforts to eliminate vivax malaria and hookworms.

Proteome profiling of cutaneous leishmaniasis lesions due to dermotropic Leishmania donovani in Sri Lanka.

Characterization of the host response in cutaneous leishmaniasis (CL) through proteome profiling has gained limited insights in leishmaniasis research, in comparison to that of the parasite. The primary objective of this study was to comprehensively analyze the proteomic profile of the skin lesions tissues in patients with CL, by mass spectrometry, and subsequent validation of these findings through immunohistochemical methods. Sixty-seven proteins exhibited significant differential expression between tissues of CL lesions and healthy controls (p<0.01), representing numerous enriched biological processes within the lesion tissue, as evident by both the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Reactome databases. Among these, the integrated endoplasmic reticulum stress response (IERSR) emerges as a pathway characterized by the up-regulated proteins in CL tissues compared to healthy skin. Expression of endoplasmic reticulum (ER) stress sensors, inositol-requiring enzyme-1 (IRE1), protein kinase RNA-like ER kinase (PERK), and activating transcription factor 6 (ATF6) in lesion tissue was validated by immunohistochemistry. In conclusion, proteomic profiling of skin lesions carried out as a discovery phase study revealed a multitude of probable immunological and pathological mechanisms operating in patients with CL in Sri Lanka, which needs to be further elaborated using more in-depth and targeted investigations.

Antimony resistance and gene expression in Leishmania: spotlight on molecular and proteomic aspects.

Leishmaniasis is a vector-borne parasitic disease caused by Leishmania parasites with a spectrum of clinical manifestations, ranging from skin lesions to severe visceral complications. Treatment of this infection has been extremely challenging with the concurrent emergence of drug resistance. The differential gene expression and the discrepancies in protein functions contribute to the appearance of 2 distinct phenotypes: resistant and sensitive, but the current diagnostic tools fail to differentiate between them. The identification of gene expression patterns and molecular mechanisms coupled with antimony (Sb) resistance can be leveraged to prompt diagnosis and select the most effective treatment methods. The present study attempts to use comparative expression of Sb resistance-associated genes in resistant and sensitive Leishmania, to disclose their relative abundance in clinical or in vitro selected isolates to gain an understanding of the molecular mechanisms of Sb response/resistance. Data suggest that the analysis of resistance gene expression would verify the Sb resistance or susceptibility only to a certain extent; however, none of the individual expression patterns of the studied genes was diagnostic as a biomarker of Sb response of Leishmania. The findings highlighted will be useful in bridging the knowledge gap and discovering innovative diagnostic tools and novel therapeutic targets.

The use of recombinant K39, KMP11, and crude antigen-based indirect ELISA as a serological diagnostic tool and a measure of exposure for cutaneous leishmaniasis in Sri Lanka.

Cutaneous leishmaniasis (CL) in Sri Lanka is caused by Leishmania donovani, a parasite widely known to cause visceral leishmaniasis. Despite the fact that CL is not generally believed to elicit serological immune responses, recent studies show the presence of antibody responses against this atypical form of CL. This study assesses the potential of using recombinant K39 (rK39), KMP11, and crude parasite antigen-based indirect ELISAs as serological diagnostic tools and measures of exposure for CL in Sri Lanka. The study used serum samples from confirmed CL patients (n = 266) and apparently healthy individuals from endemic settings (n = 411). Serum samples from individuals residing in non-endemic areas were used as negative controls. In-house indirect ELISAs were optimized and validated for recombinant antigens. Previously validated crude parasite extract-based indirect ELISA was performed for comparison. The statistical analyses were performed using SPSS v26.0. The rK39 (sensitivity = 71.2%, specificity = 64%) and KMP11 (sensitivity = 79.2%, specificity = 71.4%) based indirect ELISA were shown to be less suitable for the diagnosis of CL, while crude parasite extract-based indirect ELISA (sensitivity = 82.4%, specificity = 85.7%) might be a better method of diagnosis. All 03 ELISAs seemed to be good methods as measures of exposure since correlations were observed between the seropositivity of all 03 ELISAs (rK39: p = 0.037, KMP11: p = 0.007, CrudeAg: p = 0.000) with provincial case incidences. The findings will be important in identifying the disease hotspots in order to design the control measures for CL induced by L. donovani in Sri Lanka.

Diagnostic Tools for Cutaneous Leishmaniasis Caused by Leishmania donovani: A Narrative Review.

Leishmaniasis, a neglected tropical disease, encompasses a spectrum of clinical conditions and poses a significant risk of infection to over one billion people worldwide. Visceral leishmaniasis (VL) in the Indian sub-continent (ISC), where the causative parasite is Leishmania donovani, is targeted for elimination by 2025, with some countries already reaching such targets. Other clinical phenotypes due to the same species could act as a reservoir of parasites and thus pose a challenge to successful control and elimination. Sri Lanka has consistently reported cutaneous leishmaniasis (CL) due to L. donovani as the primary disease presentation over several decades. Similar findings of atypical phenotypes of L. donovani have also been reported from several other countries/regions in the Old World. In this review, we discuss the applicability of different methods in diagnosing CL due to L. donovani and a comprehensive assessment of diagnostic methods spanning clinical, microscopic, molecular, and immunological approaches. By incorporating evidence from Sri Lanka and other regions on L. donovani-related CL, we thoroughly evaluate the accuracy, feasibility, and relevance of these diagnostic tools. We also discuss the challenges and complexities linked to diagnosing CL and review novel approaches and their applicability for detecting CL.

Histological findings associated with treatment response in cutaneous leishmaniasis: a clinicopathological correlation study.

BACKGROUND: Treatment responses to cutaneous leishmaniasis (CL) observed in Sri Lanka show variability, ranging from quick healing to delayed or failed responses to routine medication. The determinants of these differences in treatment response are not well defined. This study aimed to identify predictive features of treatment response and outcome in localized CL caused by Leishmania donovani, focusing on both clinical and histopathological findings in the patients. METHODS: Tissue sections (n = 103) derived from 3 mm punch biopsies of parasitologically confirmed patients were assessed. Patients were followed up weekly until complete healing of skin lesions and were reviewed at the end of 6 months and 1 year. RESULTS: Healing required 7-21 weekly doses of intralesional sodium stibogluconate (IL-SSG) (mean = 12.2 ± 0.622). Twenty-nine (28.1%) patients were identified as delayed responders. None had recurred at the end of 1 year. The demographic or clinical features (age, gender, lesion type, size, location, and lesion duration) did not significantly influence the treatment response. A heavy parasite load and acanthosis were significant predictors of a delayed response to treatment (P < 0.001). Higher parasite loads were associated with inflammation of the entire dermis (P = 0.008), more intense infiltration of macrophages (p = 0.001), and epidermal atrophy (P = 0.033). Well-formed granulomas were inversely proportional to parasite loads. CONCLUSIONS: Histology findings proved to be better prognostic markers than clinical features for delayed responders to treatment and will aid in targeted patient management when tissue biopsies are performed in the initial diagnosis of CL.

Unfolded protein response pathway in leishmaniasis: A review.

Alteration in the physiological state of the endoplasmic reticulum (ER) leads to the specific response known as unfolded protein response (UPR) or ER stress response. The UPR is driven by three sensor proteins, namely: Inositol-Requiring Enzyme 1, Protein Kinase RNA-like ER kinase and Activating Transcription Factor 6 to restore ER homeostasis. Pathogenic infection can initiate UPR activation; some pathogens can subvert the UPR to promote their survival and replication. Many intracellular pathogens, including Leishmania, can interact and hijack ER for their survival and replication, triggering ER stress and subsequently ER stress response. This review aims to provide a comprehensive overview of the ER stress response in infections with the Leishmania species.

Impact of climatic factors on temporal variability of sand fly abundance in Sri Lanka: Longitudinal study (2018 to 2020) with two-stage hierarchical analysis.

Background: Phlebotomine sand flies serve as vectors for leishmaniasis, a major health concern, but a neglected tropical disease. The risk of vector activity is governed by climatic factors that vary in different geographic zones in the country. Thus, we aimed to quantify the effect of climatic variables on sand fly vector activity in ten sentinel sites across Sri Lanka. Methods: Mean rainfall, ambient temperature, relative humidity, wind speed, soil temperature, evaporation, sunshine hours, and vector densities were recorded at monthly intervals in each location from March 2018 to February 2020. The association between weather variables and sand fly densities was analysed using a two-staged hierarchical procedure; Distributed Lag Non-Linear (DLNM) modelling framework and the DLNM method implemented in the R package dlnm (version number 2.4.6). Results: Moderate rainfall values up to 120 mm per month and increasing RH up to 82 at lag of 0 months along with increasing soil temperature and evaporation rate at lag of 2 months were associated with statistically significant increase in the sand fly activity. These associations were heterogeneous across study settings. Whereas increasing ambient and soil temperature, sunshine hours, evaporation rate appeared to reduce the sand fly activity homogeneously at lag of 0 month in all the study settings. Conclusions: The abundance of sand fly vectors varied in relation to selected climatic variables, either in real-time or with a time lag. This information can be utilized for predicting sand fly densities and for the development of effective strategies to prevent leishmaniasis transmission in specific settings.

First evidence of experimental genetic hybridization between cutaneous and visceral strains of Leishmania donovani within its natural vector Phlebotomus argentipes.

Leishmaniasis is a neglected tropical disease caused by protozoan parasites of genus Leishmania, and transmitted by different species of Phlebotomine sand flies. More than 20 species of Leishmania are known to cause disease in humans and other animals. Leishmania donovani species complex is known to have a vast diversity of clinical manifestations in humans, but underlying mechanisms for such diversity are yet unknown. Long believed to be strictly asexual, Leishmania have been shown to undergo a cryptic sexual cycle inside its sandfly vector. Natural populations of hybrid parasites have been associated with the rise of atypical clinical outcomes in the Indian subcontinent (ISC). However, formal demonstration of genetic crossing in the major endemic sandfly species in the ISC remain unexplored. Here, we investigated the ability of two distinct variants of L. donovani associated with strikingly different forms of the disease to undergo genetic exchange inside its natural vector, Phlebotomus argentipes. Clinical isolates of L. donovani either from a Sri Lankan cutaneous leishmaniasis (CL) patient or an Indian visceral leishmaniasis (VL) patient were genetically engineered to express different fluorescent proteins and drug-resistance markers and subsequently used as parental strains in experimental sandfly co-infection. After 8 days of infection, sand flies were dissected and midgut promastigotes were transferred into double drug-selective media. Two double drug-resistant, dual fluorescent hybrid cell lines were recovered, which after cloning and whole genome sequencing, were shown to be full genomic hybrids. This study provides the first evidence of L. donovani hybridization within its natural vector Ph. argentipes.

Cytokine and phenotypic cell profiles in human cutaneous leishmaniasis caused by Leishmania donovani.

BACKGROUND: The innate immune mediators are likely to influence the clinical phenotype of leishmaniasis by primary responses which limit or facilitate the spread of the parasite, as well as by modulating adaptive immunity. This study investigated the response of key innate immune cells in a focus which regularly reports localised cutaneous leishmaniasis (LCL) caused by Leishmania donovani, a species which typically causes visceral disease. METHODS: Peripheral blood mononuclear cell (PBMC) derived macrophages and dendritic cells from patients with LCL and healthy controls from endemic and non-endemic areas, were stimulated with soluble Leishmania antigen (SLA). Inflammatory mediators produced by macrophages (TNF-α/TGF-ß/IL-10, ELISA; NO, Griess method) and dendritic cells (IL-12p70, IL-10, flowcytometry) and macrophage expression of surface markers of polarization, activation and maturation (flowcytometry) were determined at 24h, 48h and 72h and compared. Study was conducted prospectively from 2015-2019. RESULTS: Patient derived macrophages and dendritic cells produced higher levels of both pro and anti-inflammatory mediators compared to controls (p<0.05) with the best discrimination for active disease observed at 72h. Data demonstrated an early activation of macrophages and a subsequent pro-inflammatory bias, as indicated by temporal profiles of TNF-α/TGF-ß and TNF-α/IL-10 ratios and higher proportions of classical (M1) macrophages. Higher TGF-ß levels were observed in cells from patients with ulcerated or persistent lesions. Immune responses by cells derived from controls in endemic and non-endemic regions did not differ significantly from each other. CONCLUSIONS: The overall immunophenotypic profile suggests that LCL observed in the country is the result of a balancing immune response between pro-inflammatory and regulatory mediators. The mediators which showed distinct profiles in patients warrant further investigation as potential candidates for immunotherapeutic approaches. A comparison with visceral leishmaniasis caused by the same species, would provide further evidence on the differential role of these mediators in the resulting clinical phenotype.

Assessment of knowledge and perceptions on leishmaniasis: An island-wide study in Sri Lanka.

Cutaneous leishmaniasis (CL) is a notifiable disease in Sri Lanka with increasing case numbers reported from every part of the country. In addition to disease treatment and vector control measures, knowledge and perceptions in a community are key contributors to a successful intervention program. An island-wide survey was carried out to assess the knowledge and perceptions regarding CL across the island, with 252 confirmed CL cases and 2,608 controls. Data was collected by trained personnel, using a pre-tested Case Reporting Form (CRF). Although the percentage who referred to CL by its correct name was low (1.4%), majority stated that it is a fly induced skin disease (79.1%). Knowledge on the symptoms, curability and the name of the vector was high in these communities, but specific knowledge on vector breeding places, biting times and preventive methods were poor. The patients were more knowledgeable when compared to the controls. Differences in the level of knowledge could be identified according to the level of education of the participants as well as across the different areas of the country. The main source of information was through the healthcare system, but the involvement of media in educating the communities on the disease was minimal. While this study population was unaccustomed to the use of repellants or sprays, the use of bed nets was high (77.7% of the participants) in this study population. Although misconceptions and incorrect practices are rare in Sri Lankan communities, promoting health education programs which may improve disease awareness and knowledge on vector and its control will further strengthen the control and prevention strategies.

ELISA-based evaluation of antibody response to Leishmania in a region endemic for cutaneous leishmaniasis.

Leishmaniasis includes several clinical forms. While routine diagnosis of cutaneous leishmaniasis (CL) is by microscopy, an antibody response to CL has been reported in several recent studies. This study evaluated anti-leishmanial immunoglobulin G (IgG) antibody responses as a biomarker of active leishmaniasis and a measure of exposure to Leishmania. Sera from 50 untreated CL patients, 140 patients under treatment and 280 healthy individuals residing in endemic regions collected as part of an epidemiological survey, was analysed with an enzyme-linked immunosorbent assay established in-house using receiver operator characteristic curve at optimized cut-off value. The assay showed high performance as a diagnostic tool in identifying exposure in endemic individuals (sensitivity: 98%, specificity: 90.3%). All patients showed lower antibody levels over time since onset of lesion/s. Antibody levels were higher (p Ë‚ .01) and persisted for a longer period in untreated patients. In patients under treatment, the level of anti-IgG antibodies was negatively correlated with the total duration the patient had been on treatment. The anti-leishmanial IgG response in Leishmania donovani-induced CL is transient and is unlikely to confer protective immunity. Optimized serological assays may be useful in endemic settings for diagnosis and monitoring the treatment response in CL.

An open dataset of Plasmodium vivax genome variation in 1,895 worldwide samples.

This report describes the MalariaGEN Pv4 dataset, a new release of curated genome variation data on 1,895 samples of Plasmodium vivax collected at 88 worldwide locations between 2001 and 2017. It includes 1,370 new samples contributed by MalariaGEN and VivaxGEN partner studies in addition to previously published samples from these and other sources. We provide genotype calls at over 4.5 million variable positions including over 3 million single nucleotide polymorphisms (SNPs), as well as short indels and tandem duplications. This enlarged dataset highlights major compartments of parasite population structure, with clear differentiation between Africa, Latin America, Oceania, Western Asia and different parts of Southeast Asia. Each sample has been classified for drug resistance to sulfadoxine, pyrimethamine and mefloquine based on known markers at the dhfr, dhps and mdr1 loci. The prevalence of all of these resistance markers was much higher in Southeast Asia and Oceania than elsewhere. This open resource of analysis-ready genome variation data from the MalariaGEN and VivaxGEN networks is driven by our collective goal to advance research into the complex biology of P. vivax and to accelerate genomic surveillance for malaria control and elimination.

Treatment of Cutaneous Leishmaniasis and Insights into Species-Specific Responses: A Narrative Review.

Cutaneous leishmaniasis (CL) is a complex skin infection that has imposed a heavy burden on many developing countries and is caused by more than 20 Leishmania species. This disease is predominantly associated with disfiguring scars and major social stigma upon infection. The severity of the disease seemingly depends on many factors including the species of parasite, the host, region of endemicity, socio-economic status and the accessibility to health facilities. Despite myriad studies that have been performed on current and novel therapies, the treatment outcomes of CL remain contentious, possibly because of the knowledge gaps that still exist. The differential responses to the current CL therapies have become a major drawback in disease control, and the dearth of information on critical analyses of outcomes of such studies is a hindrance to the overall understanding. On the basis of currently available literature on treatment outcomes, we discuss the most effective doses, drug susceptibilities/resistance and treatment failures of the Leishmania genus for both monotherapy and combination therapy. This review focuses on the available treatment modalities for CL caused by different Leishmania species, with insights into their species-specific efficacies, which would inform the selection of appropriate drugs for the treatment and control of leishmaniasis.

Stress conditions promote Leishmania hybridization in vitro marked by expression of the ancestral gamete fusogen HAP2 as revealed by single-cell RNA-seq.

Leishmania are protozoan parasites transmitted by the bite of sand fly vectors producing a wide spectrum of diseases in their mammalian hosts. These diverse clinical outcomes are directly associated with parasite strain and species diversity. Although Leishmania reproduction is mainly clonal, a cryptic sexual cycle capable of producing hybrid genotypes has been inferred from population genetic studies and directly demonstrated by laboratory crosses. Experimentally, mating competence has been largely confined to promastigotes developing in the sand fly midgut. The ability to hybridize culture promastigotes in vitro has been limited so far to low-efficiency crosses between two Leishmania tropica strains, L747 and MA37, that mate with high efficiency in flies. Here, we show that exposure of promastigote cultures to DNA damage stress produces a remarkably enhanced efficiency of in vitro hybridization of the L. tropica strains and extends to other species, including Leishmania donovani, Leishmania infantum, and Leishmania braziliensis, a capacity to generate intra- and interspecific hybrids. Whole-genome sequencing and total DNA content analyses indicate that the hybrids are in each case full genome, mostly tetraploid hybrids. Single-cell RNA sequencing of the L747 and MA37 parental lines highlights the transcriptome heterogeneity of culture promastigotes and reveals discrete clusters that emerge post-irradiation in which genes potentially involved in genetic exchange are expressed, including the ancestral gamete fusogen HAP2. By generating reporter constructs for HAP2, we could select for promastigotes that could either hybridize or not in vitro. Overall, this work reveals that there are specific populations involved in Leishmania hybridization associated with a discernible transcriptomic signature, and that stress facilitated in vitro hybridization can be a transformative approach to generate large numbers of hybrid genotypes between diverse species and strains.

Image Processing for mHealth-Based Approach to Detect the Local Tissue Inflammation in Cutaneous Leishmaniasis: A Proof of Concept Study.

Skin lesions are a feature of many diseases including cutaneous leishmaniasis (CL). Ulcerative lesions are a common manifestation of CL. Response to treatment in such lesions is judged through the assessment of the healing process by regular clinical observations, which remains a challenge for the clinician, health system, and the patient in leishmaniasis endemic countries. In this study, image processing was initially done using 40 CL lesion color images that were captured using a mobile phone camera, to establish a technique to extract features from the image which could be related to the clinical status of the lesion. The identified techniques were further developed, and ten ulcer images were analyzed to detect the extent of inflammatory response and/or signs of healing using pattern recognition of inflammatory tissue captured in the image. The images were preprocessed at the outset, and the quality was improved using the CIE L∗a∗b color space technique. Furthermore, features were extracted using the principal component analysis and profiled using the signal spectrogram technique. This study has established an adaptive thresholding technique ranging between 35 and 200 to profile the skin lesion images using signal spectrogram plotted using Signal Analyzer in MATLAB. The outcome indicates its potential utility in visualizing and assessing inflammatory tissue response in a CL ulcer. This approach is expected to be developed further to a mHealth-based prediction algorithm to enable remote monitoring of treatment response of cutaneous leishmaniasis.

Treatment failure to sodium stibogluconate in cutaneous leishmaniasis: A challenge to infection control and disease elimination.

The first-line treatment for Leishmania donovani-induced cutaneous leishmaniasis (CL) in Sri Lanka is intra-lesional sodium stibogluconate (IL-SSG). Antimony failures in leishmaniasis is a challenge both at regional and global level, threatening the ongoing disease control efforts. There is a dearth of information on treatment failures to routine therapy in Sri Lanka, which hinders policy changes in therapeutics. Laboratory-confirmed CL patients (n = 201) who attended the District General Hospital Hambantota and Base Hospital Tangalle in southern Sri Lanka between 2016 and 2018 were included in a descriptive cohort study and followed up for three months to assess the treatment response of their lesions to IL-SSG. Treatment failure (TF) of total study population was 75.1% and the majority of them were >20 years (127/151,84%). Highest TF was seen in lesions on the trunk (16/18, 89%) while those on head and neck showed the least (31/44, 70%). Nodules were least responsive to therapy (27/31, 87.1%) unlike papules (28/44, 63.6%). Susceptibility to antimony therapy seemed age-dependant with treatment failure associated with factors such as time elapsed since onset to seeking treatment, number and site of the lesions. This is the first detailed study on characteristics of CL treatment failures in Sri Lanka. The findings highlight the need for in depth investigations on pathogenesis of TF and importance of reviewing existing treatment protocols to introduce more effective strategies. Such interventions would enable containment of the rapid spread of L.donovani infections in Sri Lanka that threatens the ongoing regional elimination drive.