Emergence of visceral leishmaniasis in Sri Lanka: a newly established health threat

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.

The immune response in canine and human leishmaniasis and how this influences the diagnosis- a review and assessment of recent research

Leishmaniasis is a widespread but still underdiagnosed parasitic disease that affects both humans and animals. There are at least 20 pathogenic species of Leishmania, most of them being zoonotic. The diagnosis of leishmaniasis remains a major challenge, with an important role being played by the species of parasites involved, the genetic background, the immunocompetence of the host. This paper brings to the fore the sensitivity of the balance in canine and human leishmaniasis and addresses the importance of the host's immune response in establishing a correct diagnosis, especially in certain cases of asymptomatic leishmaniasis, or in the situation the host is immunosuppressed or acquired leishmaniasis through vertical transmission. The methods considered as a reference in the diagnosis of leishmaniasis no longer present certainty, the diagnosis being influenced mostly by the immune response of the host, which differs according to the presence of other associated diseases or even according to the breed in dogs. Consequently, the diagnosis and surveillance of leishmaniasis cases remains an open topic, requiring new diagnostic methods adapted to the immunological state of the host.

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.

Assessment of Risk of Exposure to Leishmania Parasites among Renal Disease Patients from a Renal Unit in a Sri Lankan Endemic Leishmaniasis Focus

Leishmania donovani causes both cutaneous and visceral leishmaniasis (CL and VL) in Sri Lanka, where chronic kidney disease (CKD) and kidney transplant recipients' (KTR) geographical areas overlap. This study aimed to determine the risk of exposure to Leishmania infection among renal patients. This cross-sectional study in a renal unit assessed clinical symptoms and signs of CL and VL in recipients of blood/kidney or immunosuppressives. Sera were tested with Leishmania-specific DAT and rK-39 ELISA. There were 170 participants. A total of 84.1% (n = 143) were males (CKD: 101, KTR; 42, mean age 45) and 27 were females (females: CKD: 23, KTR: 4, mean age 39 years). Recipients of blood transfusion/s within last 2 years: 75.9% (CKD: 115, KTR: 14), on immunosuppressive therapy: 34.1% (CKD: 13, KTR: 45). Two CKD patients repeatedly showed clear positive titres (1: 12,800 and 1: 3200) with Leishmania-DAT and another two (CKD) became marginally positive with rK39-ELISA. Prevalence of anti-Leishmania antibodies: 2.4% (4/170). All four patients were clinically asymptomatic and were recipients of recent blood transfusions. Attributable risk of exposure to Leishmania infection through blood transfusions was 0.032, OR 2.99 (95% CI = 0.16 to 56.45, p = 0.47). Therefore, routine screening of kidney/blood donors and CKD and KTR patients in Sri Lanka may not be necessary.

An Insight Into Systemic Immune Response in Leishmania donovani Mediated Atypical Cutaneous Leishmaniasis in the New Endemic State of Himachal Pradesh, India

Leishmaniasis continues to afflict known and newer endemic sites despite global efforts towards its control and elimination. In this regard, the emergence of newer endemic sites with unusual disease formats is recognized wherein Leishmania donovani complex classically known to cause visceral disease is demonstrated to cause cutaneous manifestation. In this context, atypical cutaneous leishmaniasis (CL) cases caused by L. donovani genetic variants from the newer endemic state of Himachal Pradesh (HP) in India are beginning to be understood in terms of parasite determinants. The atypical CL manifestation further needs to be explored to define host immune correlates with a possible role in driving the unusual disease progression. In the given study, we performed comprehensive systemic-immune profiling of the atypical CL patients from the study area in HP, India, in comparison with the classical visceral leishmaniasis (VL) patients from the northeast region of India. The systemic immune response was studied using ELISA-based assessment of Th1, Th2, Th17, Treg, and Th22 specific plasma cytokine expression pattern and parasite-specific total serum IgG/IgG subclasses. The specified immune correlates are known to exhibit heterogeneous association with the different infecting parasite species, infection load, and co-lateral host immunopathology in classical CL and VL. In the atypical CL patient group, altered expression of IL-10 emerged as the key finding that could potentially fine-tune the Th1/Th17/Th22 effector cytokine axis towards a localized cutaneous manifestation. A reduced expression of IL-10 along with a high IFN-γ/IL-10 ratio as a readout of effective parasite killing defined atypical cutaneous outcome. In contrast, high circulatory IL-10 levels and a depressed IFN-γ/IL-10 ratio were seen in classical VL patients in line with an ineffective parasite-killing cytokine response. Overall, the study highlights new knowledge on host immune correlates in terms of cytokine expression pattern and IgG subclasses that underline atypical disease manifestation such that L. donovani, a generally visceralizing parasite species cause skin localized cutaneous lesions.

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.

Development of Quantitative Rapid Isothermal Amplification Assay for Leishmania donovani

Quantification of pathogen load, although challenging, is of paramount importance for accurate diagnosis and clinical management of a range of infectious diseases in a point-of-need testing (PONT) scenario such as in resource-limited settings. We formulated a quantification approach to test the standard-curve based absolute quantification ability of isothermal recombinase polymerase amplification (RPA) assay. As a test of principle, a 10-fold dilution series of Leishmania donovani (LD) genomic DNA prepared in nuclease-free-water (NFW), and from culture-spiked-blood (CSB) were tested, and a 15 min assay was performed. A modified algorithm was formulated to derive the detection outcome. The threshold-record times (Tr) in seconds thus obtained were plotted against the initial load of parasite genomes for log-linear regression analysis. The quantitative RPA (Q-RPA) assay was further evaluated against a LD quantitative (q)-PCR assay with DNA extracted from visceral and post-Kala-azar dermal leishmaniasis case specimens and stratified into different ranges of threshold cycle (Ct). The best-fitted regression models were found linear with mean r²/root mean square error (RMSE) values of residual points (in seconds) estimated as 0.996/8.063 and 0.992/7.46 for replicated series of NFW and CSB, respectively. In both series, the lower limit of detection reached less than 0.1 parasite genome equivalent DNA. Absolute agreement between Q-RPA and LD-qPCR was found for test positivity, and strong positive correlations were observed between the Tr and Ct values (r = 0.89; p < 0.0001) as well as between the absolute parasite loads (r = 0.87; p < 0.0001) quantified by respective assays. The findings in this very first Q-RPA assay for leishmaniasis are suggestive of its potential in monitoring LD load in clinical specimens, and the development of rapid Q-RPA assays for other infectious diseases.

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.

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.

First Evidence from Sri Lanka for Subphenotypic Diversity within L. donovani-Induced Classical Cutaneous Leishmaniasis

Sri Lanka reports a large focus of Leishmania donovani-induced cutaneous leishmaniasis (CL) with CL as the main clinical entity. Two independent, long existed, and clinicoepidemiologically different transmission foci in the northern region (NR) and southern region (SR) were recently reported. Current project is an extension to this previous study. Clinical diversity within a profile of classical cutaneous leishmaniasis (CCL) in a focus of L. donovani-induced CL is described for the first time. Patients with laboratory confirmed CCL (n = 550) from NF and SF were evaluated. Lesions in both foci were found to have all classical developmental stages (small and large nodules, ulcerating nodules, and ulcers) and other identified changes (multiplication, ulceration, and enlargement). Main difference was in the proportions of lesions progressing in to each different stages, proportions of lesion undergoing the main changes, and in timing of these changes during the course of a lesion. Northern focus reported a smaller proportion of lesions showing enlargement and ulceration, and a longer period of time was also required for these changes when compared to same in southern focus. In northern focus, most lesions remained small and nonulcerating and showed a higher tendency to multiply while most lesions reported in southern focus enlarged and ulcerated rapidly and remained single. Current study also evidenced a wider spectrum in the rate and pattern of progression of a skin lesion and high individual variation which could mask these region-based differences. Parasitic, vector-related, or a host etiology is suggested. Slow progressing nonulcerating infections in North may be the result of a well-adopted parasite strain that coevolved with its host for a long period while inducing only a minimal host response. This could be one among many reasons for previously observed silent expansion in northern focus while southern focus remained more confined and stable over time. Small nonprogressive, nondisturbing lesions can play a major role as silent parasite reservoirs in a community. In addition, the laboratory detection rate declined significantly when lesions multiplied and enlarged indicating the need for early laboratory confirmation. Usefulness of identified features in clinical screening and management needs to be considered.

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.

Cytokine saga in visceral leishmaniasis

In humans, infection with Leishmania manifests into a spectrum of diseases. The manifestation of the diseases depend on the resultant evasion of the parasite to immune responses namely by macrophages, which is an exclusive host of Leishmania. The B cells valiantly mount antibody responses, however, to no avail as the Leishmania parasites occupy the intracellular niches of the macrophages and subvert the immune response. Extensive studies have been documented on the role of cell-mediated immunity (CMI) in protection and counter survival strategies of the parasites leading to downregulation of CMI. The present review attempts to discuss the cytokines in progression or resolution of visceral form of leishmaniasis or kala-azar, predominantly affecting the Indian subcontinent. The components/cytokine(s) responsible for the regulation of the critical balance of T helper cells and their subsets have been discussed in the perspective. Therefore, any strategy involving the treatment of visceral leishmania (VL) needs to consider the balance and regulation of T cell function.

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).

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.

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.

Imported cutaneous leishmaniasis: molecular investigation unveils Leishmania major in Bangladesh

Background

The main clinical forms of leishmaniasis in Bangladesh are visceral leishmaniasis and post-kala-azar dermal leishmaniasis, which are caused by Leishmania donovani. Imported cutaneous leishmaniasis (CL) is emerging globally due mainly to increased human mobility. In recent years, several imported CL cases have also been reported in Bangladesh. Sporadic atypical cases of CL can be challenging for diagnosis and clinical management, while occurrence of infection on a frequent basis can be alarming. We report of a case of a Bangladeshi temporary-migrant worker who, upon return, presented development of skin lesions that are characteristic of CL.

Methods

A serum sample was collected and tested with an rK39 immunochromatographic test. Nucleic acid from skin biopsy derived culture sample was extracted and screened with a real-time PCR assay which targets the conserved REPL repeat region of L. donovani complex. The internal transcribed spacer 2 region of the ribosomal RNA gene cluster was amplified and sequenced.

Results

The suspect had a history of travel in both CL and VL endemic areas and had a positive rK39 test result. Based on clinical presentation, travel history and demonstration of the parasite in the skin biopsy, CL was diagnosed and the patient underwent a combination therapy with Miltefosine and liposomal amphotericin B. While typical endemic species were not detected, we identified Leishmania major, a species that, to our knowledge, has never been reported in Bangladesh.

Conclusions

Proper monitoring and reporting of imported cases should be given careful consideration for both clinical and epidemiological reasons. Molecular tests should be performed in diagnosis to avoid dilemma, and identification of causative species should be prioritized.

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.

Atypical leishmaniasis: A global perspective with emphasis on the Indian subcontinent

BACKGROUND

Among the neglected tropical diseases, leishmaniasis continues to be prevalent in many tropical and subtropical countries despite international, national, and local efforts towards its control and elimination over the last decade. This warrants a critical evaluation of such factors as under-reporting, asymptomatic infections, post kala azar dermal leishmaniasis (PKDL) cases, and drug resistance. In this review, we highlight lesser-understood atypical presentations of the disease involving atypical parasite strains against a background of classical leishmaniasis with a focus on the Indian subcontinent.

METHODS AND FINDINGS

A literature review based on endemic areas, the nature of disease manifestation, and underlying causative parasite was performed with data collected from WHO reports for each country. Searches on PubMed included the term ''leishmaniasis" and "leishmaniasis epidemiology" alone and in combination with each of the endemic countries, Leishmania species, cutaneous, visceral, endemic, non-endemic, typical, classical, atypical, and unusual with no date limit and published in English up to September 2017. Our findings portray a scenario with a wider distribution of the disease in new endemic foci, with new discoveries of parasite-driven atypical disease manifestations in different regions of the world. Unlike the classical picture, some Leishmania species are associated with more than one disease presentation, e.g., the L. donovani complex, generally associated with the visceral form, is now also associated with a cutaneous disease presentation, while L. tropica species complex, known to cause cutaneous disease, can cause viscerotropic disease. This phenomenon points towards the discovery of novel parasite variants as etiologic agents of atypical disease manifestations and represents an excellent opportunity to identify and study genes that control disease virulence and tropism.

CONCLUSIONS

The increased recognition of atypical leishmaniasis as an outcome of parasite variants has major implications for leishmaniasis control and elimination. Identifying molecular correlates of parasite isolates from distinct regions associated with different disease phenotypes is required to understand the current epidemiology of leishmaniasis in regions with atypical disease.

Evidence for Seroprevalence in Human Localized Cutaneous Leishmaniasis Caused by Leishmania donovani in Sri Lanka

Visceral leishmaniasis (VL) is considered as a major health threat in the Indian subcontinent. Leishmania donovani, a usually visceralizing species, causes cutaneous leishmaniasis (CL) in Sri Lanka. However, visceralizing potential of the local L. donovani is not yet fully understood. This project studied the seroprevalence of local CL by using an in-house ELISA. An IgG-based ELISA using crude Leishmania antigen (Ag) was developed and validated. A total of 50 laboratory confirmed cases of locally acquired CL were examined using the newly developed ELISA. According to the optimized ELISA, seroprevalence of anti-Leishmania IgG antibodies in the study group was 34.0% (n = 17/50). Majority of seropositive individuals were males (n = 13/17), representing 76%. Nearly half of the seropositive individuals were young adults (20–40 years, n = 9/17, 53%). Higher proportions of single lesions, large lesions, and nodular lesions were associated with a seroconversion. A proportion of local L. donovani infections leading to CL have the ability to raise an antibody response in the host. This may indicate early systemic involvement as one possibility. Study of a large number of patients with adequate follow-up would be useful.

Emergence of visceral leishmaniasis in Sri Lanka: a newly established health threat

BACKGROUND

Sri Lanka is a new focus of human cutaneous leishmaniasis caused by a genetic variant of usually visceralizing parasite Leishmania donovani. Over 3000 cases have been reported to our institution alone, during the past two decades. Recent emergence of visceral leishmaniasis is of concern.

METHODS

Patients suspected of having visceral leishmaniasis (n = 120) fulfilling at least two of six criteria (fever > 2 weeks, weight loss, tiredness affecting daily functions, splenomegaly, hepatomegaly and anemia) were studied using clinic-epidemiological, immunological and haematological parameters. Seven cases (four progressive, treated (group A) and 3 non- progressive, potentially asymptomatic and observed (group B) were identified. Clinical cases were treated with systemic sodium stibogluconate or amphotericin B and all were followed up at the leishmaniasis clinic of University of Colombo for 3 years with one case followed up for 9 years.

RESULTS

All treated cases responded well to anti leishmanial treatment. Relapses were not noticed. Clinical features subsided in all non-progressive cases and did not develop suggestive clinical features or change of laboratory parameters. Visceral leishmaniasis cases have been originated from different districts within the country. Majority had a travel history to identified local foci of cutaneous leishmaniasis.

CONCLUSION

Visceral leishmaniasis is recognized as an emerging health threat in Sri Lanka. At least a proportion of locally identified strains of L. donovani possess the ability to visceralize. Apparent anti leishmanial sensitivity is encouraging. Timely efforts in disease containment will be important in which accurate understanding of transmission characteristics, increased professional and community awareness, improved diagnostics and availability of appropriate treatment regimens.