Cutaneous Leishmaniasis Research Articles

Molecular Diagnosis of Human Cutaneous Leishmaniasis and Identification of the Causative Leishmania Species in Iran: A Narrative Review

Cutaneous leishmaniasis (CL) is a common form of leishmaniasis in underdeveloped countries. Although CL tends to be self-limiting, it can cause significant scars and may progress to more severe manifestations. Additionally, Leishmania species vary in susceptibility to the available treatments. The selection of treatment and clinical outcome of CL depend on the accurate determination of the Leishmania species. This mini-review aims to provide an overview of the molecular diagnosis techniques such as PCR-based assays, nucleic acid sequence-based amplification, and loop-mediated isothermal amplification utilized in the identification of Leishmania species in Iran.

Effect of Rodent Control Program on Incidence of Zoonotic Cutaneous Leishmaniasis, Iran.

We report the effect of a rodent control program on the incidence of zoonotic cutaneous leishmaniasis in an endemic region of Iran. A 1-year interruption in rodent control led to 2 years of increased incidence of zoonotic cutaneous leishmaniasis. Restarting rodent control led to a decline of zoonotic cutaneous leishmaniasis.

Study of the Effect of Pentostam on Some Bacterial Species Isolated from Skin Infections

In the current study, Pentostam treatment, used to treat cutaneous leishmaniasis, was used against some types of bacteria isolated from skin infections (Klebsiella and Staphylococcus) to determine the extent of the bacteria's resistance to this treatment. The results showed that staph bacteria were more sensitive than Klebsiella bacteria. On the Mueller-Hinton medium and measuring the inhibition zone, some types of vitamins were used in this study, such as vitamin C and vitamin B, without and with Pentostam, to determine their effect in increasing or decreasing the effectiveness of Albutostam against bacteria. The findings demonstrated that vitamin B did not affect the bacteria's sensitivity to vitamin C alone. However, when they were combined with pentostam treatment, the results showed that vitamin B had the effect of reducing the effectiveness of pentostam against staph. Bacteria and klebsiella bacteria, while vitamin C was shown to increase the effect of pentostam treatment on Both types of bacteria.

Clinical pattern and treatment outcome of cutaneous leishmaniasis patients in Somali region, eastern Ethiopia

AbstractBackgroundNeglected tropical diseases, affecting over a billion people, include leishmaniasis, a protozoan parasite found in over 20 species. It is classified into three types: visceral, cutaneous, and muco‐cutaneous leishmaniasis, with cutaneous leishmaniasis being the most common. Dogs and rodents are the primary reservoirs of leishmaniasis, which is transmitted by infected female sandflies. Cutaneous leishmaniasis, found on exposed parts such as the arms, face and legs, presents with diverse clinical manifestations, including erythematous lesions, large, painless nodules, ulceration and an eventual volcanic form.ObjectiveTo assess the clinical pattern and treatment outcome of cutaneous leishmaniasis patients in the Somali region of eastern Ethiopia.MethodsThis descriptive study was conducted in the Somali region using neglected tropical disease surveillance data collected from 1 September 2023, to 8 February 2024. The data were cleaned and then exported to STATA version 17 for analysis.ResultsFrom 1 September 2023, to 8 February 2024, 900 patients were diagnosed with cutaneous leishmaniasis. Of these, 105 (11.67%) patients had localised cutaneous leishmaniasis, 741 (82.33%) had disseminated cutaneous leishmaniasis, 20 (2.22%) had diffuse cutaneous leishmaniasis, 8 (0.89%) had mucocutaneous leishmaniasis, 12 (1.33%) had mucocutaneous and disseminated leishmaniasis and 14 (1.56%) had localised and mucocutaneous leishmaniasis. All of the cases were male; the most common signs and symptoms the patients showed were papule, nodule, ulcer and crust 791 (87.89%) and itching, fever and discharges 758 (84.22%), respectively. Most of the patients, 823 (93.34%), were given systemic pentavalent antimonials, and the cure rate was 886 (98.44%). Of the patients, 14 (100%) who were defaulted on had diffuse cutaneous leishmaniasis.ConclusionsAll the participants had travelled to an area where sandflies were common. The majority of patients complained of itching, fever and discharges, with over two‐thirds having disseminated cutaneous leishmaniasis (DCL) and 0.89% having mucocutaneous leishmaniasis. The regional health bureau should set up a strong surveillance system and launch educational campaigns to raise awareness about cutaneous leishmaniasis, its transmission, symptoms and preventive measures. Furthermore, patients should be advised to strictly adhere to their treatment schedule and follow‐ups.

Incidence of cutaneous Leishmaniasis in humans during the COVID-19 pandemic in Baluchistan Province, Pakistan.

Cutaneous leishmaniasis (CL) is one of the neglected tropical diseases that affects impoverished communities throughout the world. In Pakistan CL is an endemic disease. This study aimed to determine the incidence of CL infection in the Baluchistan province of Pakistan from January 2020 to March 2022 during the COVID-19 pandemic. A total of 1047 clinically suspected cases of CL from Bolan Medical College Hospital, Quetta, were followed up in the study. The data regarding the epidemiological characterstics, pathological information, and treatment of patients was collected. Out of 1047 probable cases of CL, 594 (56.73%) cases were found to be positive for CL. Females had the highest infection rate, with the majority of reported cases being in the 0-9-year age group. Most CL cases were reported in April in the year 2020, with a few cases reported in June. But in the year 2021, the highest number of cases were reported in December. The number of overall cases has gradually increased in the year 2022, most likely because of the reduction in COVID-19 pandemic restrictions. The p value for the positive as compared to suspected cases in the years 2020, 2021, and 2022 was calculated as 0.8925, 0.8763, and 0.8535 respectively. Further epidemiological studies and health education campaigns are recommended to increase public awareness. It is strongly advised that local, provincial, and national health authorities establish and maintain effective leishmaniasis surveillance systems to promptly identify disease outbreaks and implement timely control measures.

Histopathological findings and diagnosis of cutaneous leishmaniasis, confirmed by PCR, in an endemic region of Brazil.

Diagnosis of cutaneous leishmaniasis (CL) is difficult, and the correct use of histopathological criteria can be useful in clinical practice. The present study evaluates the association between histopathological findings and the results of polymerase chain reaction (PCR) in clinically suspected cases of CL. Skin samples were received in a laboratory from an endemic region of Brazil for over nine years. Associations were analyzed by means of the Chi square test with a 5% level of significance. Of the 222 examined samples, 190 (85.6%) tested positive by PCR. All 25 cases identified by microscopic examination also tested positive by PCR. Except for the more intense inflammatory infiltrate, all other evaluated histological variables (ulceration, epidermal hyperplasia, hyperkeratosis, presence of granuloma, neutrophils, histiocytes, lymphocytes, plasmocytes, and necrosis) were not significantly associated with PCR positivity. The intensity of the inflammatory infiltrate is a good indicator of the occurrence of CL. Histopathological aspects are useful to increase the predictive values of CL diagnoses, but PCR is still necessary to confirm or exclude the disease.

A Second Wind for Inorganic APIs: Leishmanicidal and Antileukemic Activity of Hydrated Bismuth Oxide Nanoparticles.

American cutaneous leishmaniasis is a disease caused by protozoa of the genus Leishmania. Currently, meglumine antimoniate is the first-choice treatment for the disease. The limited efficacy and high toxicity of the drug results in the necessity to search for new active principles. Nanotechnology is gaining importance in the field, since it can provide better efficacy and lower toxicity of the drugs. The present study aimed to synthesize, characterize, and evaluate the in vitro leishmanicidal and antileukemic activity of bismuth nanoparticles (BiNPs). Promastigotes and amastigotes of L. (V.) guyanensis and L. (L.) amazonensis were exposed to BiNPs. The efficacy of the nanoparticles was determined by measurement of the parasite viability and the percentage of infected cells, while the cytotoxicity was characterized by the colorimetry. BiNPs did not induce cytotoxicity in murine peritoneal macrophages and showed better efficacy in inhibiting promastigotes (IC50 < 0.46 nM) and amastigotes of L. (L.) amazonensis. This is the first report on the leishmanicidal activity of Bi-based materials against L. (V.) guayanensis. BiNPs demonstrated significant cytotoxic activity against K562 and HL60 cells at all evaluated concentrations. While the nanoparticles also showed some cytotoxicity towards non-cancerous Vero cells, the effect was much lower compared to that on cancer cells. Treatment with BiNPs also had a significant effect on inhibiting and reducing colony formation in HL60 cells. These results indicate that bismuth nanoparticles have the potential for an inhibitory effect on the clonal expansion of cancer cells.

Epidemiology and Genetic Characterization of Leishmania RNA Virus in Leishmania (Viannia) spp. Isolates from Cutaneous Leishmaniasis Endemic Areas in Panama.

Leishmania (Viannia) spp. can harbor a double-stranded RNA virus known as Leishmania RNA virus 1 (LRV-1), whose presence has been reported in nine countries across the Americas and seven Leishmania species. Here, we studied 100 Leishmania (Viannia) isolates from patients with cutaneous leishmaniasis collected from different endemic areas in Panama from 2016 to 2022. We identified L. (V.) panamensis, L. (V.) guyanensis, L. (V.) braziliensis/guyanensis hybrid, and L. (V.) panamensis sp.1. (genetic variant). LRV-1 was detected by RT-PCR in 9% of L. (Viannia) isolates (eight cases in L. (V.) panamensis, and one in L. (V.) guyanensis). Phylogenetic analysis based on sequencing data classified all LRV-1 isolates within genotype A, suggesting that LRV phylogenetic proximity is closely aligned with geographical distribution or to the phylogenetic proximity of the Leishmania host in the case of the L. (V.) panamensis and L. (V.) guyanensis in Panama.

In vitro and in silico antileishmania activity of voriconazole (Vfend)

American Cutaneous Leishmaniasis (ACL) is a public health problem in 88 countries. The treatment of ATL is based on pentavalent antimony, which has several adverse effects. And through new alternatives for the treatment of leishmaniasis, the use of off-label medications appears. The objective of this work was to evaluate, through in vitro and in silico tests, the activity of voriconazole in tablet form as off-label against the promastigote forms of Leishmania amazonensis and Leishmania guyanensis. In the bioassay, species of Leishmania (L.) amazonensis and Leishmania (V.) guyanensis were used, cultivated in RPMI medium with 10% SFBi. The 50% inhibitory concentration (IC50) of voriconazole was evaluated by the inhibition of promastigotes exposed to voriconazole at concentrations of 6.25 to 200 µg.mL-1 diluted in culture medium and fluconazole at 25 to 400 µg.mL-1. In the experiment, parasites plus culture medium and pentamidine isethionate at 3 µg.mL-1 were used as controls for 24, 48 and 72 h in triplicate. The concentrations of voriconazole used in the test showed antileishmanial activity against promastigotes of both Leishmania species, with an IC50 of 5.34 µg.mL-1 for L. amazonensis and 5.66 µg.mL-1 for L. guyanensis. Therefore, the study showed that off-label voriconazole presented better results than fluconazole against Leishmania species, in addition to showing better enzymatic coupling of new targets.

PLGA nanoparticle-delivered Leishmania antigen and TLR agonists as a therapeutic vaccine against cutaneous leishmaniasis in BALB/c mice

Leishmaniasis, caused by Leishmania (L.) species, remains a neglected infection. Therapeutic vaccination presents a promising strategy for its treatment. In this study, we aimed to develop a therapeutic vaccine candidate using Leishmaniaantigens (SLA) and Toll-like receptor (TLR) 7/8 agonist (R848) encapsulated into the poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs). Moreover, TLR1/2 agonist (Pam3CSK4) was loaded onto the NPs. The therapeutic effects of these NPs were evaluated in L. major-infected BALB/c mice.Footpad swelling, parasite load, cellular and humoral immune responses, and nitric oxide (NO) production were analyzed. The results demonstrated that the PLGA NPs (SLA-R848-Pam3CSK4) therapeutic vaccine effectively stimulated Th1 cell responses, induced humoral responses, promoted NO production, and restricted parasite burden and lesion size.Our findings suggest that vaccination with SLA combined with TLR1/2 and TLR7/8 agonists in PLGA NPs as a therapeutic vaccine confers strong protection againstL. majorinfection. These results represent a novel particulate therapeutic vaccine against Old World cutaneous leishmaniasis.

The contrasting phenotypes of neutrophils during asymptomatic versus symptomatic Leishmania braziliensis infection.

The mechanisms that mediate immune protection in individuals with subclinical (SC) or asymptomatic infection with L. braziliensis are largely unknown. Neutrophils (PMNs) have been implicated in progressive symptomatic cutaneous leishmaniasis (CL), but their potential participation in maintenance of subclinical infection is unexplored. The aim of this study was to compare the phenotypic and functional profiles of PMNs in individuals with SC infection versus patients with symptomatic CL due to L. braziliensis. Subjects were recruited in the endemic region of Corte de Pedra, Bahia, Brazil. Surface markers to define activation status were characterized by flow cytometry. Functional responses of PMNs including phagocytic capacity, production of oxidative species, and oxidative killing of intracellular parasites were studied in vitro. PMNs from individuals with SC infection displayed a more activated phenotype and greater ability to control the infection than PMNs from patients with CL. In contrast, PMNs from patients with CL exhibited higher expression of HLA-DR and higher production of oxidative species than PMNs from subjects with SC infection. PMNs from individuals with SC infection can control the infection more efficiently than PMNs from patients with CL, despite the lower production of oxidants. Our observations suggest that L. braziliensis may evade microbicidal mechanisms of PMNs from patients with CL, contributing to parasite dissemination and the establishment of disease.

Effect of Phlebotomus papatasi on the fitness, infectivity and antimony-resistance phenotype of antimony-resistant Leishmania major Mon-25

Leishmania major is responsible for zoonotic cutaneous leishmaniasis. Therapy is mainly based on the use of antimony-based drugs; however, treatment failures and illness relapses were reported. Although studies were developed to understand mechanisms of drug resistance, the interactions of resistant parasites with their reservoir hosts and vectors remain poorly understood. Here we compared the development of two L. major MON-25 trivalent antimony-resistant lines, selected by a stepwise in vitro Sb(III)-drug pressure, to their wild-type parent line in the natural vector Phlebotomus papatasi. The intensity of infection, parasite location and morphological forms were compared by microscopy. Parasite growth curves and IC50 values have been determined before and after the passage in Ph. papatasi. qPCR was used to assess the amplification rates of some antimony-resistance gene markers. In the digestive tract of sand flies, Sb(III)-resistant lines developed similar infection rates as the wild-type lines during the early-stage infections, but significant differences were observed during the late-stage of the infections. Thus, on day 7 p. i., resistant lines showed lower representation of heavy infections with colonization of the stomodeal valve and lower percentage of metacyclic promastigote forms in comparison to wild-type strains. Observed differences between both resistant lines suggest that the level of Sb(III)-resistance negatively correlates with the quality of the development in the vector. Nevertheless, both resistant lines developed mature infections with the presence of infective metacyclic forms in almost half of infected sandflies. The passage of parasites through the sand fly guts does not significantly influence their capacity to multiply in vitro. The IC50 values and molecular analysis of antimony-resistance genes showed that the resistant phenotype of Sb(III)-resistant parasites is maintained after passage through the sand fly. Sb(III)-resistant lines of L. major MON-25 were able to produce mature infections in Ph. papatasi suggesting a possible circulation in the field using this vector.

Evaluation of Nanonanoliposomal Curcumin on Cutaneous Leishmaniasis Skin Lesions Caused by Leishmania major in BALB/c Mice.

Curcumin is an extract of rhizome turmeric (diferuloylmethane), with antioxidant, anti-inflammatory, antimicrobial, and anti-parasitic properties, which making it a potential candidate for the treatment of leishmaniasis. The aim of the presented study was to evaluate curcumin as possible candidate for treatment of cutaneous leishmaniasis. We investigated the physicochemical properties and anti-leishmanial effects of nanoliposomal curcumin (40, 80, and 120 μM) in Leishmania major (MRHO/IR/75/ER) infected BALB/c mice at the faculty of Veterinary Medicinem University of Tehran, Iran. For this aim, L. major promastigotes (MHROM/IR/75/ER) at stationary phase (2×106) were inoculated sub-cutaneously into the upper area of the tail in BALB/c mice (six groups, n= 10 per group). For evaluation of nanoliposomal curcumin, the zeta potential, particle size and stability of nanoliposomal curcumin was determined. Furthermore, the anti-leishmanial effects of nanoliposomal curcumin formulation on the lesion sizes was determined and the parasite burden in the leishmania induced lesion was performed using semi quantitative PCR. Treatment of L. major infected BALB/c mice with nanoliposomal curcumin led to a reduction in the kinetic of the skin lesion size development. The semi quantitative PCR analysis of DNA extracted from the lesions showed reduction of parasite burden. The most effective treatment could be found in 80 μM nanoliposomal curcumin. Treatment with Glucantime, as a positive control, also showed a nearly similar effect compared to the effect of 80 μM nanoliposomal curcumin. Nanoliposomal curcumin could be considered as a potential drug against cutaneous leishmaniasis caused by L. major in susceptible animal models.

Efficacy of a Combined Herbal Product Containing Indigofera argentea, Pistacia atlantica and Salvia hispanica in Zoonotic Cutaneous Leishmaniasis Patients Treated along Glucantime ®.

Leishmaniasis is highly prevalent worldwide, and while conventional medicine offers numerous treatment methods for cutaneous leishmaniasis, Iranian traditional medicine suggests various remedies. We aimed to evaluate the efficacy of an herbal combination containing Indigofera argentea leaves, Pistacia atlantica resin, and Salvia hispanica seeds in patients with zoonotic cutaneous leishmaniasis. This study was conducted at the Leishmaniasis Department of Chabahar Health Center in southeastern Iran in 2021. It was a double-blinded randomized clinical trial involving 68 patients enrolled after clinical diagnosis, examination of smear samples using Giemsa staining, and PCR confirmation. The volunteers were randomly divided into intervention and control groups. Both groups received 'Glucantime ® as the primary medication weekly until complete healing or up to 12 weeks. Glucantime ® was administered intralesionally at a dosage of 0.1 cc on the wound's margin, with repeat injections at 1 cm intervals along the wound edge when necessary. In addition to the main drug, the intervention group received the herbal product topically twice daily until wound healing or for up to 4 weeks, while the control group received a placebo in the same manner. 82.35% of patients in the intervention group and 20.58% in the control group achieved complete healing within four weeks. There was a significant difference between the two groups (P < 0.001). The herbal product demonstrated effectiveness in treating patients with zoonotic cutaneous leishmaniasis.

Many faces of cutaneous leishmaniasis.

Our objective in this study is to determine the atypical clinical presentations of cutaneous leishmaniasis (CL) patients diagnosed in Şanlıurfa province. This retrospective study included 213 patients with atypical clinical presentations among 1751 patients diagnosed with CL between October 2019 and August 2022 in Şanlıurfa Oriental Boil Diagnosis and Treatment Center located in an endemic region for CL. We found the prevalence of atypical CL to be 12.1%. The most common atypical lesions were lupoid 21 (9.8%), erysipeloid 16 (7.5%), impetiginous 16 (7.5%), recidivan 15 (7%), eczematous 15 (7%), ecthyma-like 13 (6.1%), pyoderma gangrenous-like 12 (5.6%), and sporotrichoid 12 (5.6%). Other lesions with atypical clinical presentations: chalazion-like, verrucous, dental sinus-like, psoriasiform, zosteriform, lymphoma-like, juvenile xanthogranuloma-like, volcano-like, paronychial, basal cell carcinoma-like, squamous cell carcinoma-like, herpes labialis-like, keratoacanthoma-like, chancriform, annular, lichenoid, mastocitoma-like, keloidal, epidermoid cyst-like, kaposi sarcoma-like, scar leishmaniasis, granulomatous cheilitis-like, mycetoma-like, molluscum contagiosum-like, discoid lupus erythematosus-like, and dermatofibroma-like. In addition to the atypical clinical presentations previously reported, we also defined dermatofibroma-like, Kaposi sarcoma-like, dental sinus-like, juvenile xanthogranuloma-like, mastocytoma-like, and epidermoid cyst-like. It should be kept in mind that CL can clinically mimic many infectious, inflammatory, and neoplastic diseases, which should be considered in the differential diagnosis of long-term non-healing lesions, especially in endemic areas. Key message What is already known on this subject: CL is known as the great imitator disease in dermatology. What this study adds: In addition to the atypical clinical presentations previously reported, we also defined dermatofibroma-like, Kaposi sarcoma-like, dental sinus-like, juvenile xanthogranuloma-like, mastocytoma-like, and epidermoid cyst-like. How this study might affect research, practice, or policy: CL can clinically mimic many infectious, inflammatory and neoplastic diseases, which should be considered in the differential diagnosis of long-term non-healing lesions, especially in endemic areas.

DeepLeish: a deep learning based support system for the detection of Leishmaniasis parasite from Giemsa-stained microscope images

BackgroundLeishmaniasis is a vector-born neglected parasitic disease belonging to the genus Leishmania. Out of the 30 Leishmania species, 21 species cause human infection that affect the skin and the internal organs. Around, 700,000 to 1,000,000 of the newly infected cases and 26,000 to 65,000 deaths are reported worldwide annually. The disease exhibits three clinical presentations, namely, the cutaneous, muco-cutaneous and visceral Leishmaniasis which affects the skin, mucosal membrane and the internal organs, respectively. The relapsing behavior of the disease limits its diagnosis and treatment efficiency. The common diagnostic approaches follow subjective, error-prone, repetitive processes. Despite, an ever pressing need for an accurate detection of Leishmaniasis, the research conducted so far is scarce. In this regard, the main aim of the current research is to develop an artificial intelligence based detection tool for the Leishmaniasis from the Geimsa-stained microscopic images using deep learning method.MethodsStained microscopic images were acquired locally and labeled by experts. The images were augmented using different methods to prevent overfitting and improve the generalizability of the system. Fine-tuned Faster RCNN, SSD, and YOLOV5 models were used for object detection. Mean average precision (MAP), precision, and Recall were calculated to evaluate and compare the performance of the models.ResultsThe fine-tuned YOLOV5 outperformed the other models such as Faster RCNN and SSD, with the MAP scores, of 73%, 54% and 57%, respectively.ConclusionThe currently developed YOLOV5 model can be tested in the clinics to assist the laboratorists in diagnosing Leishmaniasis from the microscopic images. Particularly, in low-resourced healthcare facilities, with fewer qualified medical professionals or hematologists, our AI support system can assist in reducing the diagnosing time, workload, and misdiagnosis. Furthermore, the dataset collected by us will be shared with other researchers who seek to improve upon the detection system of the parasite. The current model detects the parasites even in the presence of the monocyte cells, but sometimes, the accuracy decreases due to the differences in the sizes of the parasite cells alongside the blood cells. The incorporation of cascaded networks in future and the quantification of the parasite load, shall overcome the limitations of the currently developed system.

Effects of cutaneous leishmaniasis on patients’ quality of life

IntroductionCutaneous Leishmaniasis (CL) is caused by protozoan parasite called Leishmania. It is endemic in more than 100 countries globally. Despite its vast prevalence and impact on quality of life, it is one of the most neglected tropical dermatological diseases. The CL burden has often been expressed based on the physical disfigurement caused by the disease. However, considering the impact of the disease beyond physical impairment and changes in patients’ appearance would help to better understand the disease as a public health problem. The effect of CL on patients’ quality of life was determined in this study.MethodsThe data that were related to quality of life were collected using Standard one-week Dermatology Life Quality Index (DLQI) questionnaire. The questions were categorized under seven domains: symptoms & feelings, daily activities, work and school, leisure, personal relationships, and treatment. Each question was scored on a three-point scale: Very much (3), A lot (2), A little (1), Undecided (0), and Not at all (0). The sum of the scores lied between 0 and 48. A higher score shows worse quality of life. The data were entered and analysed using Statistical Package for Social Science 23. Frequencies and proportions were used to describe the data. Differences were considered statistically significant at p < 0.05.ResultsThe lives of the majority of CL patients (60.7%) were significantly affected by CL. The quality of life of patients was moderately impacted by CL in 25% of the CL patients. In 32.1% of the CL patients, the effect of CL on patients’ quality of life was very large. The quality of one CL patient’s life was extremely largely affected. The disease had a small effect on 32.1% of the CL patients. Personal relationship was the most affected domain followed by symptoms and feelings and treatment. Future study including rural regions is required.ConclusionThe Dermatology Life Quality Index demonstrates that CL has a small to extremely very large negative effect on the quality of life of patients.

Causal association between environmental variables and the excess cases of cutaneous leishmaniasis in Colombia: are we looking to the wrong side?

Our main aim was to estimate and compare the effects of six environmental variables (air temperature, soil temperature, rainfall, runoff, soil moisture, and the enhanced vegetation index) on excess cases of cutaneous leishmaniasis in Colombia. We used epidemiological data from the Colombian Public Health Surveillance System (January 2007 to December 2019). Environmental data were obtained from remote sensing sources including the National Oceanic and Atmospheric Administration, the Global Land Data Assimilation System (GLDAS), and the Moderate Resolution Imaging Spectroradiometer. Data on population were obtained from the TerriData dataset. We implemented a causal inference approach using a machine learning algorithm to estimate the causal association of the environmental variables on the monthly occurrence of excess cases of cutaneous leishmaniasis. The results showed that the largest causal association corresponded to soil moisture with a lag of 3 months, with an average increase of 8.0% (95% confidence interval [CI] 7.7-8.3%) in the occurrence of excess cases. The temperature-related variables (air temperature and soil temperature) had a positive causal effect on the excess cases of cutaneous leishmaniasis. It is noteworthy that rainfall did not have a statistically significant causal effect. This information could potentially help to monitor and control cutaneous leishmaniasis in Colombia, providing estimates of causal effects using remote sensor variables.

Spatio-Temporal distribution of a vector of cutaneous leishmaniasis: Pintomyia longiflocosa, in a population from the Colombian Andean Mountains.

Leishmaniasis, a neglected disease and public health concern, is associated with various factors such as biological, social, economical conditions and climate, increasing the risk of human infection. Understanding the population dynamics of the vectors, like Pintomyia longiflocosa, and its relationship with ecological variables is crucial for developing effective strategies to control sand fly populations and combat cutaneous leishmaniasis in a tropical country like Colombia. Adult sand flies were collected in three different sample locations: outdoor, indoor, and peri-domestic areas in three houses located in the rural settlement of Campoalegre (Huila) between February 2020 and February 2021, using the CDC light traps. The sand fly density was quantified and associated with the sample locations and the sampling months using Analysis of Variance and Pearson correlations. In the period of the sample, 98.86% of sand fly collected was identified as Pi. longiflocosa. The density of this species was significantly different between males and females, the latter contributing more to density in all sample locations (P<0.0001). The outdoor was the sample location with the highest and most significative density in this study (70%, P = 0.04). The density of these sand flies is related to the seasonality of Campoalegre, revealing a density peak from February and June to October (P < 0.05). Finally, precipitation is the environmental variable prominently linked to the density pattern, showing a negative correlation with it. Months with the highest precipitations show the lowest values of Pi. longiflocosa abundance. Our investigation reveals a inverse correlation between precipitation levels and the abundance of Pi. longiflocosa in Campoalegre (Huila), particularly in outdoor areas. This suggests that vector control strategies to periods of reduced precipitation in outdoor settings could offer an effective approach to minimizing cases of cutaneous leishmaniasis in the region.

Prediction of preventive behaviors of cutaneous leishmaniasis in the endemic areas of northwest Iran: an application of BASNEF model

Cutaneous leishmaniasis (CL) is a disease transmitted by mosquitoes and is endemic in many regions of the world and Iran, and annually imposes a large burden on the health system. This study was conducted to identify the effective factors in the preventive behaviors of CL based on the BASNEF model in endemic areas in the northwest of Iran. This cross-sectional study was conducted in Bileh-Savar, ‘endemic areas of Ardabil Province, Iran’, from June 2022 to October 2022. 200 non-patients were included in the study by a multi-stage sampling method. A standard questionnaire based on the BASNEF model was applied for data collection. The data were analyzed using SPSS version 25. Means and standard deviations were calculated to describe the continuous variables, and multivariate linear regression analysis was used to determine the prediction of intention and behavior by the model structures. The BASNEF constructs predict 27% of behavioral intention changes. Among the constructs, attitude has a greater contribution in predicting changes (R2 = 0.27, p < 0.01). Also, the results showed that the BASNEF constructs predict 23% of behavior changes. Among the constructs, enabling factors have a greater contribution to predicting changes (R2 = 0.23, p < 0.01). This finding shows that behavior is more influenced by environmental factors, and educational interventions based on behavior change models, along with providing environmental conditions, can facilitate behavior change.