Sri Lankan cutaneous leishmaniasis is caused by Leishmania donovani zymodeme MON-37

A real-time PCR for quantification of parasite burden and its correlations with clinical characteristics and anti-rKRP42 IgG level in cutaneous leishmaniasis in Sri Lanka

In visceral and mucocutaneous leishmaniasis, humoral immune response can reflect disease severity and parasite burden. Cutaneous leishmaniasis (CL) in Sri Lanka is caused by a usually visceralizing parasite, Leishmania donovani. We assessed the parasite burden (relative quantity-RQ) in 190 CL patients using quantitative real-time PCR (qPCR-with primers designed for this study) and smear microscopy, then correlated it with clinical parameters and IgG response. RQ of parasite DNA was determined with human-specific glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as the internal control. The qPCR sensitivity was tested with serially diluted DNA from cultured L. donovani parasites. Smears were assigned a score based on number of parasites per high power field. Data from previous studies were used for comparison and correlation; nested Internal Transcribed Spacer 1 (ITS1) PCR as reference standard (RS) and IgG antibody titers to the Leishmania rKRp42 antigen as the immune response. The qPCR amplified and quantified 86.8% of the samples while demonstrating a fair and significant agreement with ITS1-PCR and microscopy. Parasite burden by qPCR and microscopy were highly correlated (r = 0.76; p = 0.01) but showed no correlation with the IgG response (r = 0.056; p = 0.48). Corresponding mean RQs of IgG titers grouped by percentiles, showed no significant difference (p = 0.93). Mean RQ was higher in early lesions (p = 0.04), decreased with lesion size (p = 0.12) and slightly higher among papules, nodules and wet ulcers (p = 0.72). Our study established qPCR's efficacy in quantifying parasite burden in Sri Lankan CL lesions but no significant correlation was observed between the parasite burden and host IgG response to the Leishmania rKRP42 antigen.

Application of CL Detect™ rapid test for diagnosis and liposomal amphotericin B for treatment of cutaneous leishmaniasis: A retrospective analysis from a tertiary care centre in a non-endemic area in India

Background Increasing urbanisation has led to the occurrence of cutaneous leishmaniasis (CL) in new areas, which was otherwise localised to endemic areas. Healthcare workers should be made aware of this entity to ensure clinical suspicion of CL and investigations needed to confirm CL. The article describes patients seen at a tertiary hospital in Delhi. Aims To establish the utility of the CL Detect Rapid test as a diagnostic tool and the efficacy of Liposomal Amphotericin B (LAmB) for the complete cure of CL patients. Methods Data of patients of CL (n = 16) was retrospectively analysed concerning diagnosis and treatment. Diagnosis rested on histopathology, real-time PCR, and CL Detect Rapid Test. Speciation of the parasite was based on the Internal transcribed spacer-I gene. Patients were treated with LAmB (i.v., 5 mg/kg up to three doses, five days apart). Results A positivity of 81.3% (95%CI, 54.4-96) was observed for CL Detect Rapid test in comparison with 100% (95%CI, 79.4-100.0) for real-time PCR and 43.8% (95%CI, 19.8-70.1) for microscopy/histopathological examination. L. tropica was the infective species in all cases. All the patients treated with LAmB responded to treatment, and 9/10 patients demonstrated complete regression of lesions, while one was lost to follow-up. Limitations It is a retrospective study, and the data includes only confirmed cases of CL at a single centre. Conclusion This study highlights the utility of CL Detect as a promising diagnostic tool and the efficacy of LAmB for the complete cure of CL.

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.

Distribution of Phlebotomus argentipes Annandale & Brunetti, 1908 in the Anuradhapura district, North Central Sri Lanka

Background & objectives

Phlebotomus argentipes Annandale & Brunetti, 1908 (Diptera: Psychodidae) is the main vector responsible for the transmission of Leishmania donovani (Laveran & Mesnil, 1903) Ross, 1903 in the subcontinent of India. It is the potential vector of cutaneous leishmaniasis in Sri Lanka. The present study determined ecological factors that influence the abundance of P. argentipes in areas with high disease prevalence in the Anuradhapura district, North Central Sri Lanka.

Methods

CDC light traps and yellow sticky traps were used for sampling, and abundance was recorded throughout 12 months with selected environmental parameters namely, relative humidity, wind speed, and temperature. The relationships between the abundance of P. argentipes with mean temperature, % relative humidity, and wind speed were tested with regression analysis. The temporal distribution of the vector population was tested with a time series analysis.

Results

The study identified the most preferable microhabitats of P. argentipes: shrubs, unclear areas, gardening areas, wet soil areas with leaf litter, and termite hills. The results indicated that the abundance of P. argentipes was highly dependent on mean temperature (P = 0.00, R2 = 68%), and a high number of P. argentipes was recorded for a low mean temperature range of 24.7-27.3°C. Furthermore, the abundance of P. argentipes exhibited an increasing trend with high humidity levels of 72-88% (P = 0.00, R2 = 91.6%).

Interpretation & conclusion

These findings may help predict the temporal variation of the potential vector population with studied ecological parameters and contribute to a successful vector management strategy with thorough knowledge of the behavioral pattern of P. argentipes.

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.

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.

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.

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.

Unusual Observations in Leishmaniasis-An Overview

Leishmaniasis significantly affects the population of the tropics and subtropics. Clinical features and infective species of Leishmania are the primary factors driving the direction of diagnosis. The rise in incidences of atypical presentations present a challenge in patient treatment. Knowledge of unusual/rare presentations can aid in having a broader perspective for including the different aspects during the examination and thus avoid misdiagnosis. A comprehensive literature survey was performed to present the array of atypical presentations confounding clinicians which have been seen in leishmaniasis. Case reports of unusual findings based on the localizations and morphology of lesions and infective species and the predominant geographical sites over almost five decades highlight such presentations in the population. Information regarding the clinical features recorded in the patient and the chosen treatment was extracted to put forward the preferred drug regimen in such cases. This comprehensive review presents various unusual observations seen in visceral leishmaniasis, post-kala-azar dermal leishmaniasis, cutaneous leishmaniasis, and mucocutaneous leishmaniasis. It highlights the need to consider such features in association with differential diagnosis to facilitate proper treatment of the patient.

Time series analysis of leishmaniasis incidence in Sri Lanka: evidence for humidity-associated fluctuations

Leishmaniasis is a vector-borne disease of which the transmission is highly influenced by climatic factors, whereas the nature and magnitude differ between geographical regions. The effects of climatic variables on leishmaniasis in Sri Lanka are poorly investigated. The present study focused on time-series analysis of leishmaniasis cases reported from Sri Lanka with selected climatic variables. Variance stabilized time series of leishmaniasis patients of entire Sri Lanka and major districts from 2014 to 2018 was fitted to autoregressive integrated moving average (ARIMA) models. All the possible models were generated by assigning different values for autoregression and moving average terms using a function written in R statistical program. The top ten models with the lowest Akaike information criterion (AIC) values were selected by writing another function. These models were further evaluated using RMSE and MAPE error parameters to select the optimal model for each area. Cross-autocorrelation analyses were performed to assess the associations between climate and the leishmaniasis incidence. Most associated lags of each variable were integrated into the optimal models to determine the true effects imposed. The optimal models varied depending on the area. SARIMA (0,1,1) (1,0,0)₁₂ was optimal for the country level. All the forecasts were within the 95% confidence intervals. Humidity was the most notable factor associated with leishmaniasis, which could be attributed to the positive impacts on sand fly activity. Rainfall showed a negative impact probably as a result of flooding of sand fly larval habitats. The ARIMA-based models performed well for the prediction of leishmaniasis in the short term.

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-β/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-β and TNF-α/IL-10 ratios and higher proportions of classical (M1) macrophages. Higher TGF-β 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.

Molecular Characterization of Leishmania Species among Patients with Cutaneous Leishmaniasis in Asir Province, Saudi Arabia

Anthroponotic cutaneous leishmaniais (ACL) and zoonotic cutaneous leishmaniasis (ZCL) caused by Leishmania tropica and Leishmania major, respectively, are endemic vector-borne diseases in southern Saudi Arabia. In 2021, an outbreak of cutaneous leishmaniasis occurred in the province of Asir. The main objective of our investigation was to analyze the epidemiological features of CL in southern Saudi Arabia. The ministry of health recorded 194 CL patients between January and December 2021 from the Asir province. Our findings showed that the majority of CL patients (87.1%) originated from the governorates of Khamis-Mushait and Abha. Most of the patients were males (62.3%). While CL affected all age groups, those under 13 years old were the most affected (38.1%). For both genders, CL patients were mostly Saudi citizens (90.7%) compared to non-Saudi expatriates. The majority of CL patients (75.2%) suffered from a single lesion, and the majority of lesions (61.3%) were located on the face. The seasonal prevalence of CL showed two peaks, a small one in July-August and a larger one in March. Of a total of 194 Giemsa slides samples, 188 showed positive amplification of Leishmania ITS1 gene. Based on PCR-RFLP and PCR-HMR, 183 patients showed positive amplification of L. tropica and five patients showed positive amplification of L. major. Phylogenetic analysis revealed a clear distinct separation between L. major and L. tropica sequences. Our results provided strong evidence of the pre-domination of L. tropica, the main etiological agent of ACL in Asir province. We reported for the first time the presence of L. major, an etiological agent of ZCL in the study areas. The co-circulation of ACL and ZCL highlighted the complexity of the epidemiology of CL in southern Saudi Arabia, and subsequently, further studies to identify competent vectors and reservoir hosts for the establishment of control strategies are needed.

Immunopathology of Cutaneous Leishmaniasis in a Cohort of Sri Lankan Patients

Introduction and objectives:

Leishmania donovani is the causative organism of leishmaniasis in Sri Lanka. Studies on the immunopathology of leishmaniasis due to L. donovani are limited. The objective of this study was to describe the immunopathological characteristics of cutaneous leishmaniasis in a cohort of Sri Lankan patients.

Methodology:

Fifty skin biopsies of cutaneous leishmaniasis confirmed by detection of organisms by histology, culture, slit-skin smear, and/or polymerase chain reaction were reviewed. The inflammatory infiltrate was characterized by immunohistochemical staining for CD4, CD8, CD20, and CD68. Associations and correlations between immunohistochemical staining pattern and the parasitic load, and patterns of inflammation were determined.

Results:

The majority of biopsies showed a CD8+/CD4− T lymphocyte predominant infiltrate (84%, n = 42). A CD68 predominant infiltrate was seen in 16%(n = 8). The mean percentage of CD8+, CD4+, CD20+, and CD68+ inflammatory cells in the biopsies were 56.1% (SD = 16.5%), 2.6% (SD = 4.5%), 12.3% (SD = 10.9%), and 25.7% (SD = 15.8%) respectively. There was no association between the predominant inflammatory cell and the degree of inflammation (P = .173), presence of high RPI (P = .922), MRI(P = .367) or presence of granuloma (P = .247).The percentage of CD4+ cells showed a positive correlation with granuloma formation (Correlation coefficient = .411, P = .03). The percentage of CD20+ cells in the infiltrate showed a positive correlation with the degree of inflammation (Correlation coefficient = .491, P = .02) and the RPI (Correlation coefficient = .334, P = .018).

Discussion and Conclusion:

Skin biopsies from cutaneous leishmaniasis due to L. donovani infection showed a CD8+/CD4− predominant infiltrate. This is similar to the findings of studies on cutaneous leishmaniasis due to some other species and suggests that the cytotoxic T cell response plays a role in infections due to L. donovani.

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 ˂ .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.

Population dynamics of phlebotomine sand flies (Diptera: Psychodidae) in cutaneous leishmaniasis endemic areas of Kurunegala District, Sri Lanka

Sand flies are the primary vectors of leishmaniasis. Disease management with effective vector control depends on the knowledge of vector population dynamics. In Sri Lanka, despite few isolated entomological collections, long-term studies are not reported to date. In the reported study, monthly entomological surveillance was conducted from May 2017 to December 2018 in Polpithigama, Maho, and Galgamuwa Medical Officer of Health (MOH) areas using standard entomological techniques. Climatic data were collected from the Department of Meteorology, Sri Lanka. Patient records were collected from each MOH office. A total of 38,339 sand flies were collected. The majority were Phlebotomus argentipes (99.50%, n = 38,147), while the rest was Sergentomyia punjabensis (0.50%, n = 192). Wind speed reduces sand fly abundance (r = -0.519, P < 0.05) evidently by limiting the movement. Rainfall increases sand fly abundance (r = 0.842, P <0.05, lag = 6 months) probably by improving favorable conditions in breeding sites. The actual effect of humidity is not conclusive without further research. The observed higher prevalence of leishmaniasis in the study sites could be due to the higher sand fly density in these areas. The number of patients shows a strong positive correlation (r = 0.516, P <0.05) to the sand fly abundance with a lag of 7 months. Systematic surveillance of sand flies as a part of general healthcare services is strongly recommended to identify and prevent possible outbreaks through timely planned vector control measures.

Development of a Highly Sensitive Nested PCR and Its Application for the Diagnosis of Cutaneous Leishmaniasis in Sri Lanka

The recent surge in cutaneous leishmaniasis (CL) in Sri Lanka has rendered clinical diagnosis difficult; thus, laboratory confirmation is indispensable. A modified (two novel inner primers to detect CL caused by Leishmania donovani) nested Internal Transcribed Spacer-1 (ITS1) PCR-Restriction Fragment Length Polymorphism (RFLP) method was developed and tested. The sensitivity of the modified nested PCR was tested using serial dilutions (103 to 10−2) of the DNA extract of a cultured L. donovani DD8 strain. Patients (n = 194) from Southern Sri Lanka were examined clinically, microscopically (Slit Skin Smear-SSS) and using the modified nested PCR. The modified nested PCR detected 2.55 fg of parasite DNA compared to ITS1 PCR (25 fg) and detected more cases than SSS (94.3% vs. 77.3%; p < 0.01). The RFLP pattern was L. donovani in all cases. The modified nested PCR performed well in clinically doubtful lesions (95% by PCR vs. 60% by SSS; p < 0.01), ulcerated nodules (91% vs. 71.8%; p < 0.01) and plaques (100% vs. 66.7%; p < 0.01). SSS demonstrated sensitivity (80.9%), specificity (81.8%), PPV (98.7%) and NPV (20.5%) against modified PCR. Low parasite loads and atypical lesions can be diagnosed by the proposed method with higher accuracy.

Validation of an In-House ELISA Method in the Diagnosis of Cutaneous Leishmaniasis Caused by Leishmania donovani in Hambantota District, Sri Lanka

Clinical diagnosis has become a challenge amidst a surge of cutaneous leishmaniasis in Southern Sri Lanka. The routine diagnostic method, slit-skin smear (SSS), has variable sensitivity, leading to undiagnosed cases. Improved diagnostics are urgently needed. We assessed a new in-house ELISA method for its diagnostic capabilities against ITS-1 nested PCR (gold standard—Gs). A cohort of 190 clinical CL cases was examined by SSS microscopy, anti-rKRP42 IgG ELISA (serum- and urine-based), and rK39-Immunochromatographic strip test. Validation was done using non-endemic sera, and cutoffs were developed using the receiver operating curve. The sensitivity of SSS for case detection was 77.9% (authors) and 76.3% (technicians). ELISA vs. Gs demonstrated sensitivity (Sn) = 94.4%; specificity (Sp) = 50.0%; positive predictive value (PPV) = 97.1%; negative predictive value (NPV) = 33.3%; Kappa agreement (Kp) = 0.39/p < 0.01. Comparison of the combination method (SSS by technicians and ELISA) vs. Gs showed: Sn = 98.9%; Sp = 30.0; PPV = 96.2; NPV 60.0%; Kp = 0.378/p < 0.01. All methods performed better compared to SSS (29.4%) where the clinical diagnosis was doubtful (PCR = 94.15%; serum ELISA = 88.2%; combination = 94.1%; p < 0.01 for all). High serum anti-rKRP42 titers were seen in those with multiple lesions. Anti-rKRP42 urine ELISA was suboptimal as a diagnostic test. A 9% rate of positivity was seen for rk39-ICT, and positives recorded high anti-rKRP42 titers. The diagnostic accuracy can be increased above the level of the Gs by combining SSS and ELISA. Advanced studies are required to understand the association between rk39-ICT positivity and high anti-rKRP42 titers.

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.

Early reduction in PD-L1 expression predicts faster treatment response in human cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is caused by Leishmania donovani in Sri Lanka. Pentavalent antimonials (e.g., sodium stibogluconate [SSG]) remain first-line drugs for CL with no new effective treatments emerging. We studied whole blood and lesion transcriptomes from Sri Lankan patients with CL at presentation and during SSG treatment. From lesions but not whole blood, we identified differential expression of immune-related genes, including immune checkpoint molecules, after onset of treatment. Using spatial profiling and RNA-FISH, we confirmed reduced expression of programmed death-ligand 1 (PD-L1) and indoleamine 2,3-dioxygenase 1 (IDO1) proteins on treatment in lesions of a second validation cohort and further demonstrated significantly higher expression of these checkpoint molecules on parasite-infected compared with noninfected lesional CD68+ monocytes and macrophages. Crucially, early reduction in PD-L1 but not IDO1 expression was predictive of rate of clinical cure (HR = 4.88) and occurred in parallel with reduction in parasite load. Our data support a model whereby the initial anti-leishmanial activity of antimonial drugs alleviates checkpoint inhibition on T cells, facilitating immune-drug synergism and clinical cure. Our findings demonstrate that PD-L1 expression can be used as a predictor of rapidity of clinical response to SSG treatment in Sri Lanka and support further evaluation of PD-L1 as a host-directed therapeutic in leishmaniasis.

An investigation of a new cutaneous leishmaniasis endemic area in Western Sri Lanka

BACKGROUND

The aim was to investigate an emerging focus of cutaneous leishmaniasis (CL) in Gampaha district, Western Sri Lanka.

METHODS

Sociodemographics of CL patients in Mirigama, Gampaha district, were compared with controls using a structured questionnaire. Clinical data and geographic positioning system coordinates of patients were recorded. Sandflies collections were performed in four selected sites using indoor hand collection (162 units) and cattle-baited net traps (n=3).

RESULTS

Of 73 patients (mean age 43.6 y; SD 20), 58.9% were males. Lesions consisted of nodules (52.1%) and ulcers (47.9%). Single lesions were seen in 69.9% of patients, while 30.1% had multiple lesions. Except for one mucosal lesion, all the others were cutaneous. Treatment consisted of sodium stibogluconate and cryotherapy (46.6%), sodium stibogluconate (45.2%) or cryotherapy (8.2%). Multiple lesions were more likely to receive combination therapy (p=0.013). The majority of those employed (81.1%; 27/33) were engaged in outdoor work. Male gender, low education attainment and poor disease awareness were significant risk factors for CL (p<0.05). Four households reported multiple cases. Phlebotomus argentipes was detected in all cattle-baited net traps and 35.3% of indoor hand collection units.

CONCLUSIONS

CL is emerging in Gamapha district with Mirigama as the epicentre. Case distribution indicates local transmission, with P. argentipes as the probable vector.

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.

Genetic diversity and population structure of Phlebotomus argentipes: Vector of Leishmania donovani in Sri Lanka

Phlebotomus argentipes is the vector of Leishmania donovani which causes the disease leishmaniasis, a neglected tropical disease and a growing health problem in Sri Lanka. A proper understanding of the population genetic structure of sand fly vectors is considered important prior to planning and implementation of a successful vector control program. Thus, the present study was conducted to determine the population genetic structure of sand fly vectors in Sri Lanka. Two mitochondrial genes namely Cytochrome c oxidase subunit 1 (Cox 1) and Cytochrome b (Cytb), and the internal transcribed spacer 2 (ITS2) region from the nuclear ribosomal DNA were used for molecular characterization. Analyses included maximum likelihood method, network analysis and DNA polymorphisms. The outcome revealed unique sequences of all genomic regions studied except the cox 1 gene had a relationship with sand flies isolated previously from Sri Lanka, India and Israel and cytb gene of 4 sand flies that aligned with those isolated earlier from Sri Lanka and 3 from Madagascar. Furthermore, cox 1 gene and ITS 2 region analyses based on F_ST values indicated a possible gene flow between the study sites whereas cytb gene analysis favoured the existence of genetically distinct populations of P. argentipes in each of the study sites. Poor population differentiation of P. argentipes, a possible consequence of a gene flow, is indeed of concern due to the risk imposed by promoting the spread of functionally important phenotypes such as insecticide resistance across the country, making future vector control efforts challenging.

Diagnosing human cutaneous leishmaniasis using fluorescence in situ hybridization

Cutaneous leishmaniasis (CL) is endemic in Sri Lanka. Giemsa-stained slit-skin-smears (SSS-Giemsa) and histology are routinely used in diagnosis with a sensitivity of 40-70%. PCR currently has limited accessibility. Therefore, we assessed the sensitivity and specificity of a previously described fluorescence in situ hybridization assay, on skin smears and biopsy samples to overcome the limitations encountered with routine diagnostic methods.Samples from a total of 123 suspected CL patients were collected and subjected to SSS-Giemsa, fluorescence in situ hybridization (FISH) on slit skin smears (SSS-FISH), formalin-fixed-paraffin-embedded-tissues stained with Hematoxylin & Eosin staining (FFPE-H&E) and FISH on formalin-fixed-paraffin-embedded-tissues (FFPE-FISH). Negative controls of 61 patient samples were collected from a CL non-endemic area and subjected to the same procedures. The gold standard PCR was used as a comparator. For FISH, two previously described cyanine 3 tagged Leihsmania genus-specific probes were used.Compared to PCR, SSS-Giemsa, SSS-FISH, FFPE-H&E, and FFPE-FISH had sensitivities of 76.5%, 79.1%, 50.4% and 80.9%, respectively. Routine diagnostic tests (SSS-Giemsa and FFPE-H&E) had a specificity of 100%. SSS-FISH and FFPE-FISH had specificities of 96.7% and 93.4%, respectively. FFPE-FISH had a statistically significant higher diagnostic performance than FFPE-H&E (p < 0.001). The relative performance of SSS-Giemsa, SSS-FISH and FFPE-FISH was similar (p > 0.05 for all comparisons).We conclude that FFPE-FISH is a more accurate diagnostic tool than FFPE-H&E. SSS-FISH did not have an additional advantage over SSS-Giemsa in diagnosis. However, SSS-FISH could be recommended as a minimally invasive method in studies assessing wound healing where immunological probes are used.

Typical and atypical cutaneous leishmaniasis in Himachal Pradesh (India)

BACKGROUND

Visceral leishmaniasis (VL) is in elimination phase in India while cutaneous leishmaniasis (CL) is being reported from new foci. In Himachal Pradesh (HP), a foci of CL had been reported along Satluj River, but the causative agent poses a dilemma, hence the present study was undertaken in Shimla, Kullu and Kinnaur districts.

METHODS

A total of 28 CL patients from Indira Gandhi Medical College and Hospital Shimla (IGMC) in 2018, were tested by rK39., Twelve fresh cases were subjected to microscopic detection of Leishmania parasite, PCR and sequencing. Skin biopsies of 3-4 mm diameter were cultured, as well as imprints were prepared for the detection of Leishmania amastigotes. Biopsy samples were inoculated into different culture media (M199, RPMI 1640, NNN) and were incubated at 22-24 °C. Polymerase chain reaction (PCR) was performed to characterize Leishmania parasite species.

RESULTS

Of 28 patients, one was positive by rK39 dipstick test and one imprint was found positive for Leishmania amstigotes. Twelve biopsy DNA samples subjected to PCR for Leishmania kDNA, were found Lesihmania positive. Identification of Leishmania species was confirmed by PCR-RFLP and sequencing method. Of 12 Leishmania positive samples, six were identified as L. donovani, three L. tropica, two L.major and one remained unidentified.

CONCLUSIONS

This study revealed the existence of three species of parasites i.e., L. donovani, L. tropica and L. major indicating the existence of typical and atypical leishmaniasis in Himachal Pradesh. The occurrence of CL cases in HP, Kerala or elsewhere should not be ignored considering them just cases of CL alone. Further studies are warranted to confirm the existence of L.donovani zymodeme MON37 from cases of CL in HP or L.donovani zymodeme MON2 strain causing VL in Bihar. Elimination of CL should also be considered along with goal of Kala -Azar elimination.

Detection of Leishmania donovani DNA within Field-Caught Phlebotomine Sand Flies (Diptera: Psychodidae) in Three Cutaneous Leishmaniasis Endemic Foci of Kurunegala District, Sri Lanka

Leishmaniasis is a parasitic infection transmitted through the bite of female phlebotomine sand flies. Microscopy is the gold standard to detect parasites within the sand flies and for vector incrimination. However, molecular-based detection has become more popular nowadays in the identification of Leishmania parasites since it provides detection and species identification simultaneously with no need of laborious procedures. The entomological surveys were conducted monthly from May to October 2017 using standard entomological techniques. Field-caught sand flies were identified to the species level followed by DNA extraction. The polymerase chain reaction (PCR) was performed using species-specific primers to detect Leishmania donovani parasites. A total of 1,662 sand flies were encountered from the entomological surveys, and the majority of them were Phlebotomus argentipes (n = 1517; 91.27%), while others were Sergentomyia punjabiensis (n = 140; 8.72%). Leishmania donovani parasite DNA was detected only from P. argentipes (2.3%; n = 2). The detection of Leishmania DNA in P. argentipes suggests the possible role of this species as a vector for leishmaniasis in Sri Lanka.

Leishmaniasis: where are we and where are we heading?

Leishmaniasis is a zoonotic disease in humans caused by the bite of a parasite-infected sandfly. The disease, widely referred to as "poor man's disease," affects millions of people worldwide. The clinical manifestation of the disease depends upon the species of the parasite and ranges from physical disfigurement to death if left untreated. Here, we review the past, present, and future of leishmaniasis in detail. The life cycle of Leishmania sp., along with its epidemiology, is discussed, and in addition, the line of therapeutics available for treatment currently is examined. The current status of the disease is critically evaluated, keeping emerging threats like human immunodeficiency virus (HIV) coinfection and post kala-azar dermal leishmaniasis (PKDL) into consideration. In summary, the review proposes a dire need for new therapeutics and reassessment of the measures and policies concerning emerging threats. New strategies are essential to achieve the goal of leishmaniasis eradication in the next few decades.

Spatiotemporal distribution of cutaneous leishmaniasis in Sri Lanka and future case burden estimates

BACKGROUND

Leishmaniasis is a neglected tropical vector-borne disease, which is on the rise in Sri Lanka. Spatiotemporal and risk factor analyses are useful for understanding transmission dynamics, spatial clustering and predicting future disease distribution and trends to facilitate effective infection control.

METHODS

The nationwide clinically confirmed cutaneous leishmaniasis and climatic data were collected from 2001 to 2019. Hierarchical clustering and spatiotemporal cross-correlation analysis were used to measure the region-wide and local (between neighboring districts) synchrony of transmission. A mixed spatiotemporal regression-autoregression model was built to study the effects of climatic, neighboring-district dispersal, and infection carryover variables on leishmaniasis dynamics and spatial distribution. Same model without climatic variables was used to predict the future distribution and trends of leishmaniasis cases in Sri Lanka.

RESULTS

A total of 19,361 clinically confirmed leishmaniasis cases have been reported in Sri Lanka from 2001-2019. There were three phases identified: low-transmission phase (2001-2010), parasite population buildup phase (2011-2017), and outbreak phase (2018-2019). Spatially, the districts were divided into three groups based on similarity in temporal dynamics. The global mean correlation among district incidence dynamics was 0.30 (95% CI 0.25-0.35), and the localized mean correlation between neighboring districts was 0.58 (95% CI 0.42-0.73). Risk analysis for the seven districts with the highest incidence rates indicated that precipitation, neighboring-district effect, and infection carryover effect exhibited significant correlation with district-level incidence dynamics. Model-predicted incidence dynamics and case distribution matched well with observed results, except for the outbreak in 2018. The model-predicted 2020 case number is about 5,400 cases, with intensified transmission and expansion of high-transmission area. The predicted case number will be 9115 in 2022 and 19212 in 2025.

CONCLUSIONS

The drastic upsurge in leishmaniasis cases in Sri Lanka in the last few year was unprecedented and it was strongly linked to precipitation, high burden of localized infections and inter-district dispersal. Targeted interventions are urgently needed to arrest an uncontrollable disease spread.

Spatial Epidemiologic Trends and Hotspots of Leishmaniasis, Sri Lanka, 2001-2018

Leishmaniasis, a neglected tropical disease, is on the decline in South Asia. However, cases of cutaneous leishmaniasis have risen in Sri Lanka since 2001, and the lack of in-depth research on its epidemiologic characteristics hampers control efforts. We analyzed data collected from patients with cutaneous leishmaniasis in Sri Lanka during 2001-2018 to study temporal and geographic trends and identify and monitor disease hotspots. We noted a progression in case rates, including a sharp rise in 2018, showing temporal expansion of disease-prevalent areas and 2 persistent hotspots. The northern hotspot shifted and shrank over time, but the southern hotspot progressively expanded and remained spatially static. In addition, we noted regional incidence differences for age and sex. We provide evidence of temporally progressive and spatially expanding incidence of leishmaniasis in Sri Lanka with distinct geographic patterns and disease hotspots, signaling an urgent need for effective disease control interventions.

Therapeutic Response to Thermotherapy in Cutaneous Leishmaniasis Treatment Failures for Sodium Stibogluconate: A Randomized Controlled Proof of Principle Clinical Trial

Treatment failure to intralesional sodium stibogluconate (IL-SSG) is a health challenge for cutaneous leishmaniasis (CL) in Sri Lanka. A randomized controlled proof of principle clinical trial, with two arms (viz., radio frequency-induced heat therapy [RFHT] by a ThermoMed™ device and thermotherapy by a handheld exothermic crystallization thermotherapy for CL [HECT-CL] device) was conducted on 40 CL treatment failures to IL-SSG, from three hospitals in Tangalle, Hambantota, and Anuradhapura, from January 2017 to January 2018, followed up for 180 days post-thermotherapy with a final follow-up in February 2020. Intention-to-treat cure rates were calculated at day 90 (initial cure rate) and at day 180 (final cure rate) posttreatment. Radio frequency-induced heat therapy group: the initial cure rate was 100% (20/20) and the final cure rate was 95% (19/20), with one patient relapsing. The HECT-CL group: both the initial and final cure rates were 80% (16/20), with no relapses and one excluded from the trial. In February 2020 (1.6-3 years posttreatment), 27 traceable patients (RFHT = 16, HECT-CL = 11) remained healed. Second-degree burns were observed with RFHT in 65% (13/20), with HECT-CL in 15% (3/20), which completely resolved subsequently. The cure rates between the two treatment groups were comparable (P = 0.15). Radio frequency-induced heat therapy consumed less time and required only a single hospital visit. Handheld exothermic crystallization thermotherapy for CL is potentially usable at community settings with both being less costly than IL-SSG. This study is the first proof that thermotherapy is an efficacious and safe treatment for CL patients in Sri Lanka, complicated by treatment failure to IL-SSG.

First Serological Study Revealing High Humoral Response and Evidence for Antigenic Heterogeneity in Leishmania donovani Induced CL in Sri Lanka

Posing a threat to the ongoing leishmaniasis elimination efforts in the Indian subcontinent, L. donovani-induced cutaneous leishmaniasis (CL) has been recently reported in many countries. Sri Lanka reports a large focus of human cutaneous leishmaniasis (CL) caused by Leishmania donovani, a usually visceralizing parasite. Enhanced case detection, early treatment, and in-depth understanding of sequalae are required to contain the spread of disease. Visceralizing potential of dermotropic strains has not been fully ruled out. Sri Lankan strains have shown a poor response to established serological assays. The present concern was to develop an in-house serological assay and to determine the seroprevalence of CL for identifying visceralizing potential and its usefulness in enhancing case detection. Crude cell lysate of dermotropic L. donovani promastigotes-based indirect enzyme-linked immunosorbent assay (ELISA) was previously optimized. Assay was evaluated using sera from 200 CL patients, 50 endemic and 50 nonendemic healthy controls, 50 patients with other skin diseases, and 50 patients with other systemic diseases. Seroprevalence and clinicoepidemiological associations were analyzed. Assay was compared with light microscopy (LM) and in vitro culturing (IVC). Cost comparison was carried out. Seroprevalence of CL was 82.0%. The assay had 99.5% specificity, and all healthy controls were negative at 0.189 cut-off. Positive and negative predictive values were 99.4% and 84.7%, respectively. Positivity obtained in ELISA was comparable to LM and higher than that of IVC. Cost per patient was 3.0 USD for both ELISA and LM and 6.0 USD for IVC. Infections occurring in all age groups and both genders demonstrated >75.0% of seropositivity. Patients had lesions with different durations/types/sizes showed >70.0% of seropositivity. Study identified a high seroprevalence of L. donovani-induced CL for the first time, indicating potential for visceralization or transient serological response. This can be used as a second line test in LM-negative CL cases to enhance clinical case detection. Further studies are warranted to examine in-depth correlations, antigen profiles, comparison with other established serological tools, and usefulness in the detection of asymptomatic cases. (National patent LK/P/1/19697).

The Leishmania donovani species complex: A new insight into taxonomy☆

Among the 20 or so Leishmania spp. described as pathogenic for humans, those of the Leishmania donovani complex are the exclusive causative agents of systemic and fatal visceral leishmaniasis. Although well studied, the complex is taxonomically controversial, which hampers clinical and epidemiological research. In this work, we analysed 56 Leishmania strains previously identified as L. donovani, Leishmania archibaldi or Leishmania infantum, isolated from humans, dogs and sandfly vectors throughout their distribution area. The strains were submitted to biochemical and genetic analyses and the resulting data were compared for congruence. Our results show: i) a partial concordance between biochemical and genetic-based data, ii) very limited genetic variability within the L. donovani complex, iii) footprints of frequent genetic exchange along an east-west gradient, marked by a widespread diffusion of alleles across the geographical range, and iv) a large-scale geographical spreading of a few genotypes. From a taxonomic point of view, considering the absence of relevant terminology in existing classes, the L. donovani complex could be treated as a single entity.

Prevalidation of an ELISA for Detection of a New Clinical Entity: Leishmania donovani-Induced Cutaneous Leishmaniasis

Human leishmaniasis which is considered a neglected tropical parasitic disease presents in three main clinical forms (i.e., cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), and visceral leishmaniasis (VL)) that are mainly determined by its causative species. Leishmania donovani, the most virulent and visceralizing parasite, is increasingly reported to cause CL in many countries in the world. Although CL is generally not considered to evoke a humoral immune response except for a nonrobust and a variable response in minority of cases, VL is associated with a clear strong humoral response. However, humoral response in L. donovani-induced CL has not been well evaluated before. A suitable serology-based assay is an essential primary step in such a study. An indirect enzyme-linked immunosorbent assay (ELISA) based on Leishmania promastigote crude antigen (Ag) was designed and optimized in order to utilize in further serological studies on this new clinical entity. Optimization included quantification of crude Ag, checkerboard titration method for determination of optimal concentrations for coating Ag, human sera and secondary antibody (Ab) with suitable coating buffer, blocking buffer, and incubating temperatures. The selected coating buffer was 0.02 M phosphate buffer, pH 6.8, and the blocking buffer was 2% fetal bovine serum with 0.01 M phosphate-buffered saline. At least 1 μg of crude Ag was required for coating the ELISA plate, while 1 : 1000 serum was used as primary Ab. The optimized concentration of secondary Ab was 1 : 64000 which might be altered according to manufacturer recommendations. The assay specificity was pre-evaluated using sera (n = 20 from each category) from confirmed CL patients and controls (other skin diseases which mimic CL, other systemic diseases that mimic VL, nonendemic healthy controls, and endemic healthy controls). This procedure described an optimization procedure of an ELISA technique for detection of anti-Leishmania antibodies in patients with L. donovani caused CL.

Is leishmaniasis adequately notified in Sri Lanka? A survey among doctors from an endemic district, Sri Lanka

Background

Leishmaniasis is a notifiable disease in Sri Lanka since 2008. Previous studies show a gap in the notification of leishmaniasis. The purpose of the present study was to determine the Knowledge, attitudes and practice of medical officers regarding leishmaniasis.

Methods

A cross-sectional study was conducted in the Anuradhapura district which reported the highest case load of leishmaniasis. Medical officers from public and private health care institutes in the area filled a self-administered questionnaire in the presence of the investigators.

Results

One hundred and eighty-eight (188) medical officers completed the questionnaire. Of them, 95.7% were aware of leishmaniasis as a parasitic infection and 84.7% correctly identified Leishmania donovani as the causative organism in Sri Lanka. From the respondents, 181 (96.8%) knew that the vector of leishmaniasis is sand fly. Cutaneous leishmaniasis was reported as the most prevalent form of leishmaniasis in the country by 176 (94.1%). Nearly half of the respondents (98, 54.1%) were aware of the fact that the Anuradhapura district has the highest disease burden. Many of them had the idea that leishmaniasis is an emerging disease (155, 84.3%,) and early diagnosis is important in controlling the disease (163, 89.1%). Although about three fourth (123, 73.7%,) of the participants mentioned that leishmaniasis should be notified at first clinical suspicion, only 74 (42.5%) were aware that it is a legal requirement. Some medical officers (39, 22%) believed that the current notification system in the country is not effective. Unavailability of notification forms (60, 36.8%) heavy workload (85, 50.3%) and inadequate supportive staff (55, 35.1%) were reported as barriers for timely notification. Even though 105 (58.0%) of medical officers had suspected leishmaniasis during the last 8 years period only 35 (19.4%) had notified.

Conclusions

Even though more than 90% of the participants had good theoretical knowledge about leishmaniasis; notification of leishmaniasis is considerably inadequate. This study emphasizes the need for greater efforts to improve the notification of leishmaniasis in Sri Lanka.

A Comprehensive Review of Cutaneous Leishmaniasis in Sri Lanka and Identification of Existing Knowledge Gaps

Purpose

Sri Lanka is endemic to cutaneous leishmaniasis and reported as the latest focus of leishmaniasis in the Asian subcontinent. Annually, the number of leishmaniasis cases is increasing; therefore, more efficient diagnostic tools, treatment methods and effective prevention measures are indispensable. For this reason, many studies were conducted regarding leishmaniasis infections in Sri Lanka; however, some areas need more attention. Thus, in this review, we comprehensively discussed the studies on leishmaniasis carried out in Sri Lanka.

Methods

Published articles on leishmaniasis in Sri Lanka were searched on PubMed, Google Scholar and ResearchGate databases. Inclusion criteria for the articles were based on keyword searches including ‘Leishmaniasis in Sri Lanka’, ‘Leishmaniasis vector in Sri Lanka’, ‘Sandfly species in Sri Lanka’, ‘Leishmaniasis epidemiology in Sri Lanka’ which are publicly accessible as of 15th July 2019.

Results

In this study, we evaluated and summarized the leishmaniasis reports in Sri Lanka and mainly focused on clinical presentation of leishmaniasis infection, genetic characteristics of Leishmania donovani Sri Lankan strain, geographical distribution and associated environmental factors, immunological aspects of the infection, vector, reservoir host, risk factors, diagnosis and treatment, and prevention and control. Furthermore, we identified the areas where further research is needed to fill the essential knowledge gaps.

Conclusions

Leishmaniasis has become a critically important parasitic infection in Sri Lanka, whereas the significant clinical form is cutaneous leishmaniasis. Prevalence of the leishmaniasis infections is reported from all the districts of the country. Therefore, more studies are essential to be carried out to fill the existing knowledge gaps emphasized in this review.

Prevalence of cutaneous leishmaniasis infection and clinico-epidemiological patterns among military personnel in Mullaitivu and Kilinochchi districts of the Northern Province, early war-torn areas in Sri Lanka

BACKGROUND

The 30-year-old armed conflict in Sri Lanka resulted in a general breakdown of civil administration in the Northern and Eastern provinces, leading to mobilisation of many armed forces personnel to assist with reconstruction and resettlement. This occupational group has been identified as a priority risk group for leishmaniasis.

METHODS

Individuals enlisted at all military establishments in Mullaitivu and Kilinochchi districts, Northern Province of Sri Lanka were included. Five thousand individuals were screened for skin lesions between September 2018 and August 2019. Persons with lesions suspected as cutaneous leishmaniasis (CL) were further investigated. Information on sociodemographic/other potential risk factors was obtained through an interviewer-administered structured questionnaire. The diagnosis was confirmed by microscopic visualization of parasitic stages from different samples obtained (skin scraping, lesion aspirate and tissue impression smears), histopathology and polymerase chain reaction DNA amplification.

RESULTS

Among 5000 individuals screened, 74 individuals were suspected of having CL. Of these, 67.6% (n = 50) patients were confirmed for CL by microscopy. Around two third of both males (67.6%; n = 48) and females (66.6%; n = 2) were positive for Leishmania. The soldiers belonging to 26-35-year age group reported the highest susceptibility (83.3%; OR: 4.83, 95% CI: 3.49-6.20%). Of the sociodemographic factors, age, wearing short-sleeved upper body clothing as the uniform and non-use of insect repellents were identified as significant risk factors. Most of the CL patients had a single lesion (86.0%; n = 43) of an ulcerative type (34.0%; n = 17), mostly on their upper limb (67.9%; n = 34). Lesions were mostly 5-10 mm diameter (59.9%; n = 30) in size with poorly defined margins (72.0%; n = 36). Amongst the diagnostic techniques, microscopic examination of slit skin smear and tissue impression smear were able to discriminate the majority of patients (92.1%; n = 46) for CL.

CONCLUSIONS

In order to highlight the true burden of leishmaniasis in the military personnel, cases of leishmaniasis from military institutes should be recognized as a different entity per say and be included in the national figures so as to depict the real magnitude of the disease burden amongst this high-risk group.

Insecticide susceptibility of the sand fly leishmaniasis vector Phlebotomus argentipes in Sri Lanka

Background

Leishmania donovani-induced and sand fly-transmitted leishmaniasis is a growing health problem in Sri Lanka. Limited knowledge on biological and behavioral characteristics of probable vector Phlebotomus argentipes hinders disease control. Here, insecticide susceptibility patterns of P. argentipes were investigated with exploration of probable underlying resistance mechanisms.

Methods

Adult sand flies were collected using standard cattle baited net traps and CDC light traps from selected sites in four districts. Adult F1 progeny of P. argentipes were exposed to different concentrations of DDT, malathion, deltamethrin and propoxur using WHO susceptibility bioassay kits. Post-1-h knockdown and post-24-h mortality were recorded and analyzed. Metabolic enzyme activity and the sensitivity of the acetylcholinesterase target-site were determined by biochemical assays using wild-caught flies. Extracted fly DNA samples were tested for the presence of knockdown-resistance (kdr) type mutations.

Results

The LC₁₀₀ values for DDT, malathion, propoxur and deltamethrin were 0.8–1.5%, 0.9–2.0%, 0.017–0.03% and 0.007% respectively. Insecticide-susceptibility levels were higher than the discriminating dosages established for Aedes mosquitoes, except for malathion. The lowest susceptibility levels (except for deltamethrin) were detected in the Mamadala population, whereas the highest levels were detected in the Mirigama population. The percentage of knocked-down sand flies was < 75% at any tested concentration, including those, which exhibited 100% mortality after 24 h. Elevated activity levels of glutathione S-transferase (3%, 7%, 12.5% and 14%) and esterase (2%, 5%, 5.5% and 6.5%) were detected in flies that originated from Mirigama, Pannala, Thalawa and Mamadala respectively, while monooxygenase quantities remained below the cut-off level. Ten to 34.5% of flies were heterozygous for acetylcholinesterases target-site insensitivity, associated with organophosphate and carbamate resistance. Pyrethroid-resistance-associated L1014F kdr-type mutation in the voltage gated sodium channel gene was detected in 30/53 flies.

Conclusions

Populations of P. argentipes in Sri Lanka are largely susceptible to common insecticides, except for malathion (used extensively in the past for malaria control). Their insecticide susceptibility appears negatively associated with past malaria endemicity of the study sites, with signs of early insecticide tolerance. Presence of insecticide target site insensitivity in a notable proportion of flies and enhanced insecticide metabolizing enzyme activities imply potential future challenges for leishmaniasis control, with a call for urgent proactive measures for its containment.

Socioeconomic, demographic and landscape factors associated with cutaneous leishmaniasis in Kurunegala District, Sri Lanka

Background

Leishmaniasis is a neglected tropical disease that affects countries in the developing world. In Sri Lanka, cutaneous leishmaniasis is the most common form of the disease. It is prevalent in dry and intermediate zones, mostly associated with rural settings. Understanding basic risk factors is critical in the management of the disease with effective interventions. This study is focused on assessing the demographic, socioeconomic and landscape factors associated with leishmaniasis in Kurunegala District, Sri Lanka.

Methods

A descriptive cross-sectional study was conducted. Households of the past patients and randomly selected households, which had no history of leishmaniasis cases were interviewed. The clinical, socioeconomic, demographic, landscape and awareness-related data were obtained using a pre-tested, interviewer-administered questionnaire.

Results

A total of 101 patients and a similar number of controls were included in the study. All the patients had the cutaneous form of the disease. Housewives and personnel with monthly incomes less than Rs. 10,000 (56.76 USD) were 3.9- and 9.5-times more prone to the disease, respectively, according to multivariate analysis. Presence of decaying garbage, termite hills, unclear areas, wet soil and gardening areas were always associated with the increased odds of acquiring the disease.

Conclusions

Demographic factors do not play a pivotal role in the prevalence of leishmaniasis in the area. Housewives, inhabitants with low incomes and individuals who live in areas with conditions suitable for sand fly breeding and resting are major groups with a higher risk of infection. Special attention must be given in raising awareness and environmental management in control activities.

Histopathology of Cutaneous Leishmaniasis Caused by Leishmania donovani in Sri Lanka

Cutaneous leishmaniasis (CL) is a neglected tropical disease that is gaining importance in Sri Lanka and internationally. The clinical presentation, pathology, and method of parasite elimination in CL vary according to the species. Leishmania donovani is the causative organism for leishmaniasis in Sri Lanka. This collaborative cross-sectional study describes the clinicopathological features of cutaneous leishmaniasis among personnel of the tri-forces serving in the North and East of the country. The histology of fifty cases of CL confirmed by at least two methods (slit skin smear, lesion aspirate, tissue impression, and histology) was reviewed. The parasitic load was assessed semiquantitatively. The histological features were correlated with the clinical presentation and organism load. The majority (89.8%; n = 44) presented with a single lesion mostly located in the upper limb (69.4%). The lesion types included papule (34.7%), nodule (32.7%), and an ulcer (30.6%). The evolution time of lesions averaged 31.55 weeks. Epidermal changes were observed in 49 of the biopsies and included hyperkeratosis (90.0%; n = 45), acanthosis (44.0%; n = 22), atrophy (34.0%; n = 17), and interface change (66%; n = 33). Dermal changes were seen in all cases and were characterized by a lymphohistioplasmacytic inflammatory infiltrate of variable intensity with ill-formed granuloma in 19 cases (38%) and well-formed epithelioid granulomas in 22 cases (44%). Focal necrosis was present in 20% (n = 10). Leishmania amastigote forms were observed in 88% (n = 44). Transepidermal elimination (P = 0.025), granuloma (P = 0.027) formation, and type of lesion (P = 0.034) were significantly associated with the organism load. Granuloma formation was associated with a reduction in organism load, indicating that the macrophage activation played an important role in the control of the organism.

Establishment of a Colony of Phlebotomus argentipes under Laboratory Conditions and Morphometric Variation between Wild-Caught and Laboratory-Reared Populations

The field-based studies on sand flies are not adequate to uncover information required for the control of the leishmaniasis through reduction of vector populations. Therefore, establishment and maintenance of laboratory colonies of sand flies is an essential step in leishmaniasis research. In the current study, a colony of P. argentipes was established from wild-caught sand flies following standard procedures from the published literature. Morphological measurements of laboratory-reared and wild-caught individual sand flies were compared to assess the difference between two groups. The colony was successfully established under confined laboratory conditions. The comparison of morphometric parameters revealed that the laboratory-reared sand flies are significantly larger than those caught from wild, suggesting a possibility of increased fitness of sand flies under favorable environmental conditions which may cause higher prevalence in the disease. The current study reports the first successful attempt in colonizing sand flies under laboratory conditions. However, the colony data suggest that the conditions extracted from the published literature need to be optimized to suit local settings in order to achieve maximum population sizes within the available amount of resources.

A case of high altitude cutaneous leishmaniasis in a non-endemic region in Nepal

A case of cutaneous leishmaniasis was discovered in a 32-year old man with a persistent erythematous plaque. The patient resides in a high altitude (~2000 m above sea level) area that is not endemic for cutaneous leishmaniasis in the Dunai village of Dolpa, Nepal. The patient's lesion was initially misdiagnosed as lupus vulgaris. After response failure to initial treatment, additional testing by histological microscopy revealed the presence of Leishmania amastigotes in tissue from the lesion, and the diagnosis of cutaneous leishmaniasis was confirmed by nested PCR DNA assay of tissue from the lesion, and by a positive rK39 test in blood. Sequencing of the kinetoplast region confirmed the presence of Leishmania donovani complex. The patient responded well to treatments for cutaneous leishmaniasis and the skin lesions regressed after 6 months. This is the first known case of cutaneous leishmaniasis in a patient in Nepal who resides at high altitude in a non-endemic region. Increasing temperatures in this region of Nepal may be expanding the range of vectors that transmit cutaneous leishmaniasis.

In-situ immune profile of polymorphic vs. macular Indian Post Kala-azar dermal leishmaniasis

Post Kala-azar Dermal Leishmaniasis (PKDL), a sequel of apparently cured Visceral Leishmaniasis presents in South Asia with papulonodular (polymorphic) or hypomelanotic lesions (macular). Till date, the polymorphic variant was considered predominant, constituting 85–90%. However, following active-case surveillance, the proportion of macular PKDL has increased substantially to nearly 50%, necessitating an in-depth analysis of this variant. Accordingly, this study aimed to delineate the cellular infiltrate in macular vis-à-vis polymorphic PKDL. To study the overall histopathology, hematoxylin and eosin staining was performed on lesional sections and phenotyping by immunohistochemistry done in terms of dendritic cells (CD1a), macrophages (CD68), HLA-DR, T-cells (CD8, CD4), B-cells (CD20) and Ki67 along with assessment of the status of circulating homing markers CCL2, CCL7 and CXCL13. In polymorphic cases (n = 20), the cellular infiltration was substantial, whereas in macular lesions (n = 20) it was mild and patchy with relative sparing of the reticular dermis. Although parasite DNA was identified in both variants by ITS-1 PCR, the parasite load was significantly higher in the polymorphic variant and Leishman-Donovan bodies were notably minimally present in macular cases. Both variants demonstrated a decrease in CD1a⁺ dendritic cells, HLA-DR expression and CD4⁺ T-cells. In macular cases, the proportion of CD68⁺ macrophages, CD8⁺ T-cells and CD20⁺ B-cells was 4.6 fold, 17.0 fold and 1.6 fold lower than polymorphic cases. The absence of Ki67 positivity and increased levels of chemoattractants suggested dermal homing of these cellular subsets. Taken together, as compared to the polymorphic variant, patients with macular PKDL demonstrated a lower parasite load along with a lesser degree of cellular infiltration, suggesting differences in host-pathogen interactions, which in turn can impact on their disease transmitting potential and responses to chemotherapy.

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Comparative analysis of immunopathology of polymorphic vs. macular PKDL.

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Dense lymphohistiocytic infiltrate in polymorphic PKDL.

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Mild and patchy cellular infiltration in macular PKDL with minimal Leishman Donovan bodies.

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Decreased presence of CD1a, HLA-DR and CD4⁺ T-cells in both variants.

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The presence of CD8⁺, CD68⁺and CD20⁺ cells in polymorphic>>>macular PKDL.

Diagnosing Cutaneous leishmaniasis using Fluorescence in Situ Hybridization: the Sri Lankan Perspective

Cutaneous leishmaniasis (CL) caused by Leishmania donovani MON-37 is becoming a major public health problem in Sri Lanka, with 100 new cases per month being reported in endemic regions. Diagnosis of CL is challenging for several reasons. Due to relative specificity and rapidity we propose Fluorescence in Situ Hybridization as a diagnostic tool for CL. The objective was to evaluate the potential of Fluorescence in Situ Hybridization as a diagnostic method for Cutaneous leishmaniasis in Sri Lanka. Literature on current laboratory tests used to diagnose Cutaneous leishmaniasis in Sri Lanka and globally was reviewed. Sri Lankan data were reviewed systematically following the PRISMA guidelines. A narrative of the results is presented. There is currently no gold standard diagnostic method for Cutaneous leishmaniasis. Fluorescence in Situ Hybridization has been previously applied to detect dermal pathologies including those involving infectious agents, and its use to detect the Leishmania parasite in human cutaneous lesions reported in small number of studies, generally with limited numbers of subjects. Advantages of FISH has been specificity, cost and ease-of-use compared to the alternatives. Based on the available literature and our current work, FISH has potential for diagnosing CL and should now be evaluated in larger cohorts in endemic regions. FISH for CL diagnosis could find application in countries such as Sri Lanka, where laboratory facilities may be limited in rural areas where the disease burden is highest.

Role of Histopathology in the Diagnosis of Cutaneous Leishmaniasis: A Case-Control Study in Sri Lanka

Cutaneous leishmaniasis (CL) displays a spectrum of manifestations clinically and histologically. Then, it becomes a diagnostic challenge and must discern from the other clinical and histological mimics, especially when the Leishman-Donovan bodies are inattentive. In this study, we compared the distinguishing histomorphological characteristics of CL against the other skin diseases with similar clinical and histological features. Skin biopsies of 181 patients, which suspect CL clinically, are evaluated histologically. Pertaining to the first case-control comparison, which performed between skin lesions of CL with or without discernible organisms and the other granulomatous dermatitis, highlighted that the ill-formed coalescent granulomata (OR = 14.83) and diffuse dense dermal plasma cell infiltrate (OR = 74.25) are significantly associated with the skin lesions of CL. The second case-control analysis was between CL without discernible organisms and the other granulomatous dermatitis, and identified a significant association in the presence of ill-formed coalescent granulomata (OR = 16.94) and diffuse dense (>50/HPF) dermal plasma cell infiltrate (OR = 74.5) in the skin lesions of CL. Pertaining to epidermal changes, acanthosis (OR = 2.38), spongiosis (OR = 9.13), and the presence of ulceration (OR = 20.26) are among the major concerns in CL. In conclusion, in the presence of clinical suspicion, dermal granulomata in ill-formed coalescent morphology with high plasma cell density in a diffuse arrangement are positive factors for the diagnosis of CL, especially when the discernible Leishmania amastigotes are absent. Resource utilization such as polymerase chain reaction and other ancillary techniques during the diagnosis of CL can be minimized by using a range of histopathological features and special attention should be focused on this in the future.

First Evidence for Two Independent and Different Leishmaniasis Transmission Foci in Sri Lanka: Recent Introduction or Long-Term Existence?

Cutaneous leishmaniasis caused by a genetic variant of L. donovani is being reported from Sri Lanka since year 2001. Patients presented from different geographical locations (600 patients from North or South and a minority of cases from other foci, 2001-2013) were studied. Analysis revealed two different sociodemographic and clinical profiles of leishmaniasis in Northern and Southern Sri Lanka. Also, the same different profiles were present in these foci since the onset of the recent outbreak and had independently propagated within each focus over the time. A profile of 14 parameters identified in the Northern focus was further examined with regard to other locations. Northwestern (10/14) and Central parts (9/14) of the island were more similar to Northern focus (14/14). Infection would have originated in one focus and spread to other 2 in Northern Sri Lanka. Southern focus was different from and appeared older than all others (2/14). Western focus that accommodates a large transient population had a mixed picture of North and South features (4/14). Lesions in North showed a slow progression and a nonulcerative nature (128/185, 69.2%), while those in South showed a rapid progression and less nonulcerative lesions (193/415, 46.5%). Clinical analysis favoured a parasite aetiology (considerable strain differences) rather than a host aetiology (age, gender, or genetics). Both foci demonstrated a biannual seasonal variation since the onset of the epidemic. Two peaks were observed during the early and latter parts of the year. Furthermore, long-term existence and recent spatiotemporal expansion and detection of leishmaniasis in this country rather than a recent introduction and establishment were indicated by these findings. Vigorous antimalarial activities that existed in Sri Lanka until few decades ago, lack of professional awareness, and more recent military activities that brought human population in close contact with a sylvatic cycle would have played a role in silent propagation of Leishmania parasites and subsequent increment in human cases, respectively, in this country.

A highly sensitive modified nested PCR to enhance case detection in leishmaniasis

BACKGROUND

Human leishmaniasis is one of the major parasitic diseases with worldwide distribution. Sri Lanka is a recently established focus of leishmaniasis caused by a variant Leishmania donovani. Early case detection and management is a main approach identified for L. donovani control in the regional leishmaniasis elimination drive. Usefulness of light microscopy and in-vitro culture are limited in chronic, atypical or treated lesions though timely and accurate detection of all light microscopy/in-vitro culture negative cases of all forms of leishmaniasis is necessary for treatment. Timely treatment is important to minimize risk for death in visceral disease and undesired sequelae of long standing infection and illness on both patients and community. We described a 100% sensitive, Leishmania spp. specific modified version of a nested PCR (Mo-STNPCR) that also minimizes carry over and cross contaminations while facilitate investigation of light microscopy and in-vitro culture negative clinically suggestive cases of leishmaniasis.

METHODS

Leishmania DNA was amplified using previously published P221: 5'-GGTTCCTTTCCTGATTTACG-3' and P332: 5'-GGCCGGTAAAGGCCGAATAG-3'outer primers followed by a nested reaction using P223: 5'-TCCCATCGCAACCTCGGTT-3' and P333: 5'-AAGCGGGCGCGGTGCTG-3' inner primers that by passes the requirement of tube handling between the two steps of the conventional nested PCR. Leishmania DNA was detected in a range of infected tissue material. Infected material from patients with cutaneous leishmaniasis (n = 30), visceral leishmaniasis (n = 10) and from a control group including patients with non-leishmanial skin diseases (n = 10), other systemic diseases (n = 10) and healthy individuals (n = 10) were examined with Mo-STNPCR. Results were further compared with those of light microscopy and in-vitro culture.

RESULTS

Mo-STNPCR method was 100% sensitive and 100% specific for diagnosis of leishmaniasis. Light microscopy and in-vitro culture were positive in 75.0% (n = 30/40) and 72.5% (n = 29/40) samples respectively where combined results of them gave 87.5% (n = 35/40) sensitivity. Mo-STNPCR did not cross react with control samples. Furthermore, Mo-STNPCR reduces the risk of cross-contaminations and carry over contaminations since the full reaction is carried out without opening the tubes. Per patient cost was calculated as 22 USD while the same was 3 and 6 USD for light microscopy and in-vitro culture respectively.

CONCLUSION

Mo-STNPCR method is a useful tool in detecting leishmaniasis in minority of cases that go undetected by first line investigations.

Leishmania donovani Induced Cutaneous Leishmaniasis: An Insight into Atypical Clinical Variants in Sri Lanka

Sri Lanka is a recent focus having Leishmania donovani induced cutaneous leishmaniasis (CL) as the main clinical entity. A separate clinical entity within profile of CL was described in this study. Laboratory confirmed cases of CL (n= 950, 2002-2014) were analysed. Most lesions showed known classical developmental stages of CL (CCL) observed in other CL endemic settings while few cases (13%, 122/950) showed atypical skin manifestations (ACL). Clinical, geographical, and treatment response patterns of ACL were different from those of CCL. ACL was mainly found among males (68.0%), in 21-40 year age group (51.6%), and reported delayed treatment seeking (23.5% vs 16.3% in CCL), more nonclassical onset (lesions other than acne form <1cm sized papules), (12.1 vs 2.7%, P<0.05.), more head and neck lesions (41.5%. vs 27.2%), more large lesions (>4cm), (18.6 vs 9.9%), and poor laboratory positivity rates (65.6% vs 88.2%) when compared to CCL. When compared to lesions reporting a typical onset, lesions reporting nonclassical onset were more likely to develop ACL later on (50.1% vs 10.7%). As compared to lesions on limbs, those on head and neck and trunk were more likely to be ACL (7.0%, 16.3%, and 22.8%, respectively, P<0.05). ACL features were not age or gender dependent. Highest proportion within ACL category (32.8%) and small proportion of CCL (10.1%) originated from less leishmaniasis prevalent areas (other regions) (P<0.05). North reported more ACL than South (15.9% vs 7.4%). A total of 95 CL cases with a significant travel history were further analyzed. Residents of other regions when acquired infection from North or South developed more ACL than residents in North or South (60.9% vs 15.9% and 42.9% vs 7.4% respectively). Patients in other regions when travelled to North developed more ACL than when they travelled to South (60.9%, 42.9%). ACL and CCL required an average of 18 doses over 16.7 months and 10 doses over 12 weeks, respectively, to achieve a complete clinical cure. Underlying host immunological factors, parasite strain variations and regional variations of both could be underlying etiologies. Established independent transmission within less leishmaniasis prevalent regions combined with an unusual clinical picture leading to poor clinical suspicion and low laboratory confirmation rate will pose potential difficulties in early case detection in these highly populated and commercialized areas. This in turn will further facilitate silent and high disease transmission.

Trends in Recently Emerged Leishmania donovani Induced Cutaneous Leishmaniasis, Sri Lanka, for the First 13 Years

Sri Lanka reports a large epidemic of cutaneous leishmaniasis (CL) caused by an atypical L. donovani while regional leishmaniasis elimination drive aims at achieving its targets in 2020. Visceralization, mucotrophism, and CL associated poor treatment response were recently reported. Long-term clinico-epidemiological trends (2001-2013) in this focus were examined for the first time. Both constant and changing features were observed. Sociodemographic patient characteristics that differ significantly from those of country profile, microchanges within CL profile, spatial expansion, constant biannual seasonal variation, and nondependency of clinical profile on age or gender were evident. Classical CL remains the main clinical entity without clinical evidence for subsequent visceralization indicating presence of parasite strain variation. These observations make a scientific platform for disease control preferably timed based on seasonal variation and highlights the importance of periodic and continued surveillance of clinic-epidemiological and other characteristics.

Assessment of intralesional cytokine profile of cutaneous leishmaniasis caused by Leishmania donovani in Sri Lanka

BACKGROUND

Cytokines play a vital role in the host immune response to infection by initiating the healing process and/or accelerating the progression of the disease in cutaneous leishmaniasis (CL). Very little evidence is available on cytokine profiles and their regulatory function in CL patients in Sri Lanka. The aim of this study was to determine the cytokine expression pattern of IFN-γ, IL-4, IL-11 and IL-12p40 in CL patients and in healthy volunteers. Patients with suspected CL lesions attending to the Dermatology Clinic at the Anuradhapura Teaching Hospital were included in the study. Reverse transcription real time polymerase chain reaction (real-time RT-PCR) was performed to determine the relative expression level of target cytokines. Expression levels were quantified by 2- ∆∆CT equation.

RESULTS

The expression of cytokines IFN-γ, IL-4, IL-11 and IL-12p40 were significantly higher in CL patients compared to healthy volunteers (p <  0.05). There was a significant association between the expression of IFN-γ and the duration of the lesion (p = 0.021). Wet CL lesions showed significantly higher expression of IL-4, IL-11 and IL-12p40 (p = 0.039, 0.018 and 0.021 respectively) compared to dry lesions. Papulo-nodular lesions showed significantly high expression of IFN-γ (p = 0.023). However, cytokine expression was not significantly associated with the number, size and the locations of lesions.

CONCLUSIONS

The expression levels of all cytokines tested in the present study were significantly (p <  0.05) high in CL patients. Th1 response (IFN-γ and IL-12p40) had higher expression levels compared to Th2 (IL-4) and IL-11 in CL patients.

Cutaneous leishmaniasis in Sri Lanka: effect on quality of life

BACKGROUND

The quality of life in many patients is affected by skin lesions. Cutaneous leishmaniasis (CL), the commonest form of leishmaniasis, is no exception. In Sri Lanka, CL is an emerging parasitological condition with over 3,000 cases within the last decade. Lesions are often seen on exposed parts of the body which may cause social stigma, and hence a study was done to assess the changes in quality of life of CL patients.

METHOD

A total of 294 patients (200 civilians and 94 army personnel) answered a previously validated Sinhala self-administered Dermatology Life Quality Index (DLQI) questionnaire and an interviewer-administered questionnaire.

RESULTS

From the majority of the civilian population, 47% had no effect on their quality of life due to CL lesions, 33.5% were affected in a small way, 12.5% were affected moderately, 6.5% suffered in a large way, and 0.5% (one patient) were extremely affected due a large ulcerative lesion being on the face. The effect on quality of life was negligible in the majority of army patients as well (35.1% no effect, 31.9% small effect), with a few patients affected moderately and very largely (22.3 and 10.6%, respectively). The most affected domain in patients was symptoms and feeling 1.27 ± 1.400 (mean ± SD), and the least was the relationships domain 0.27 ± 0.625.

CONCLUSION

CL does not seem to affect the quality of life in the majority of Sri Lankan patients when compared to CL in other parts of the world or other skin diseases.

Genomic insights into virulence mechanisms of Leishmania donovani: evidence from an atypical strain

Background

Leishmaniasis is a neglected tropical disease with diverse clinical phenotypes, determined by parasite, host and vector interactions. Despite the advances in molecular biology and the availability of more Leishmania genome references in recent years, the association between parasite species and distinct clinical phenotypes remains poorly understood. We present a genomic comparison of an atypical variant of Leishmania donovani from a South Asian focus, where it mostly causes cutaneous form of leishmaniasis.

Results

Clinical isolates from six cutaneous leishmaniasis patients (CL-SL); 2 of whom were poor responders to antimony (CL-PR), and two visceral leishmaniasis patients (VL-SL) were sequenced on an Illumina MiSeq platform. Chromosome aneuploidy was observed in both groups but was more frequent in CL-SL. 248 genes differed by 2 fold or more in copy number among the two groups. Genes involved in amino acid use (LdBPK_271940) and energy metabolism (LdBPK_271950), predominated the VL-SL group with the same distribution pattern reflected in gene tandem arrays. Genes encoding amastins were present in higher copy numbers in VL-SL and CL-PR as well as being among predicted pseudogenes in CL-SL. Both chromosome and SNP profiles showed CL-SL and VL-SL to form two distinct groups. While expected heterozygosity was much higher in VL-SL, SNP allele frequency patterns did not suggest potential recent recombination breakpoints. The SNP/indel profile obtained using the more recently generated PacBio sequence did not vary markedly from that based on the standard LdBPK282A1 reference. Several genes previously associated with resistance to antimonials were observed in higher copy numbers in the analysis of CL-PR. H-locus amplification was seen in one cutaneous isolate which however did not belong to the CL-PR group.

Conclusions

The data presented suggests that intra species variations at chromosome and gene level are more likely to influence differences in tropism as well as response to treatment, and contributes to greater understanding of parasite molecular mechanisms underpinning these differences. These findings should be substantiated with a larger sample number and expression/functional studies.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5271-z) contains supplementary material, which is available to authorized users.