Leishmaniasis diagnosis: an update on the use of parasitological, immunological and molecular methods

A novel colorimetric assay for early differentiation of mucocutaneous and cutaneous leishmaniasis via species-specific identification

Mucocutaneous leishmaniasis (MCL) is a severe and debilitating progression of cutaneous leishmaniasis (CL) that occurs when the disease spreads to involve mucosal tissues. Contrasting CL, which can often be treated with local therapies, MCL requires aggressive systemic treatment, strict adherence to a 30-day regimen and regular monitoring to prevent recurrence. These requirements highlight the critical need for accurate and rapid early diagnosis to guide effective treatment strategies. However, differentiating between the Leishmania species responsible for MCL and CL remains a significant challenge, particularly in resource-limited settings. To address this gap, this study introduces a novel colorimetric assay that integrates the Spin-Tube platform with Dynamic Chemical Labeling (DCL) technology for species-specific identification of Leishmania parasites. This approach targets single nucleotide fingerprints (SNFs) within the conserved hsp70 gene, allowing precise differentiation between species associated with MCL and CL. The assay employs single-plex PCR followed by DCL-based detection of SNFs, providing rapid and visually interpretable results to facilitate species differentiation. The assay demonstrated remarkable sensitivity, with a detection limit of 1 copy of parasite DNA per μL and performed effectively even under resource-limited conditions. It was used to identify ten MCL patients, with the results confirmed through DNA sequencing. Its simplicity and rapid turnaround could make it an ideal diagnostic solution for endemic regions. By providing accurate early differentiation between CL and MCL, this assay enables the implementation of personalised treatment plans, minimising unnecessary exposure to toxic therapies and reducing the risk of irreversible mucosal damage for affected patients.

Comprehensive insights into leishmaniasis: From etiopathogenesis to a novel therapeutic approach

Leishmaniasis is a vector-borne disease caused by protozoan parasites of the genus Leishmania and is transmitted through the bites of infected sandflies. The disease is characterized by a variety of clinical manifestations, from small skin blemishes to large deformable ulcers, classified as cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL) and disseminated cutaneous leishmaniasis (DCL), as well as severe systemic infections (Kala-Azar or visceral leishmaniasis [VL]), affecting the spleen and liver, along with atypical forms such as lupoid leishmaniasis. As one of the world's most neglected tropical diseases, leishmaniasis threatens more than 1 billion people globally, with 12 million currently affected and <1.3 million new cases reported annually. This review provides comprehensive insights into the etiopathogenesis of leishmaniasis and explores the complex life cycle of parasites and their interactions with host immune responses. A systematic literature search was conducted across databases such as PubMed, Google Scholar, and Scopus via keywords such as "Leishmaniasis," "etiopathogenesis," "cutaneous leishmaniasis," "visceral leishmaniasis," and "Novel therapeutic approaches." Relevant studies published after 2015 were critically analyzed to present the current understanding of the disease mechanisms involved. It also highlights the current treatment landscape, emphasizing the emergence of drug resistance and the need for novel therapeutic approaches. Recent advancements in drug delivery systems, such as nanoparticle formulations, have shown promise for enhancing treatment efficacy and reducing toxicity. Additionally, integrated control measures, such as vector management and public education, are crucial for mitigating disease spread. This overview underscores the urgent need for continued research and innovation to combat this neglected tropical disease effectively.

Advancing diagnosis of feline Leishmania infantum infection through experimental insights

In this study, we aimed to identify the clinical findings and efficacy of different diagnostic methods in feline visceral leishmaniasis (FVL) experimental model. Healthy adult cats were divided into trial and control groups. The first and second trial groups received 108 and 109 promastigotes of leishmania infantum (L. infantum) in the stationary phase intravenously and sterile isotonic distilled water (DW) was inoculated for control cats by the same volume and route. The follow-up examination was done up to 24 weeks post-inoculation(PI). Daily clinical examination and monthly blood sampling were done for serological, molecular, hematological, and biochemical evaluations. Bone marrow (BM) aspiration was started from the second month and repeated every 2 months until the end of study. Finally the cats were euthanized and histopathological examination and organ culture were performed. The blood and bone-marrow samples of all inoculated cats were positive at nested polymerase chain reaction (N-PCR) from the second and 8 weeks PI respectively and remained positive during the study. L. infantum amastigotes were detected in BM direct smear after 12 weeks and BM culture was positive at this time. N-PCR of Liver and lymph nodes, were positive in three cats in each experimental groups. In histopathological examination, amastigotes were not observed in organs but sinus histiocytosis in the spleen and lymphoid hyperplasia were the major histopathological changes. All cats remained seronegative in enzyme-linked immunosorbent assay (ELISA) until the end of the study. All infected cats had a reasonable healthand no significant alteration in laboratory findings was noted. Long-lasting parasitemia and the presence of L. infantum in bone marrow, revealed that cats could be considered as secondary reservoirs for L. infantum. N-PCR is the best screening diagnostic method because the humoral immune response is not well activated in the feline model and antibody titers were not detected in the initial phase of L. infantum infection. Further studies are crucial to elucidate the immune system function and pathogenesis of L. infantum in cats.

Advances and Challenges in the Diagnosis of Leishmaniasis

Leishmaniasis remains a significant public health challenge, particularly in endemic regions with limited resources. Traditional diagnostic methods, including microscopy, culture, and serology, though widely utilized, often suffer from limitations such as variable  sensitivity, time delays, and the need for specialized infrastructure. Some of these limitations have been addressed with the emergence of molecular diagnostic techniques. Quantitative PCR (q-PCR), loop-mediated isothermal amplification (LAMP), and recombinase polymerase amplification (RPA) assays have improved  the diagnostic sensitivity and specificity, enabling species identification and detection of asymptomatic infections. Further, nanodiagnostics and portable sequencing technologies such as the MinION™, along with lab-on-chip platforms, are revolutionizing the diagnostic landscape of leishmaniasis by offering point-of-care (POC) options for remote settings and field-based diagnosis. This review provides an in-depth analysis of these cutting-edge advances, discusses their application in resource-constrained settings, and evaluates their potential to reshape the future of leishmaniasis diagnosis and management.

Leishmaniasis in deployed military populations: A systematic review and meta-analysis

Leishmaniasis affects military personnel deployed to endemic areas following exposure to sand flies infected with the protozoa Leishmania. This systematic review and meta-analysis of data specific to military populations aims to identify knowledge gaps to mitigate sand fly exposure and Leishmania transmission during deployments. The review was registered on PROSPERO (CRD42023463687). Random-effects meta-analyses and narrative synthesis were performed. Thirty-six studies were included, most of which reported on cutaneous leishmaniasis (CL), showing a mean cumulative incidence of 10% (95% CI: 5-16), suggesting higher rates in the Eastern Mediterranean region (14% [95% CI: 12-16]) compared to the African region (8%) and American region (9%). Asymptomatic Leishmania infection had a cumulative incidence of 11% (95% CI: 6-17), with higher rates in Eastern Mediterranean countries (20% [95% CI: 14-25]). Diagnosis involved parasitological, serological, and molecular methods, with L. (L) mexicana and L. (V.) braziliensis identified as the predominant CL pathogens in deployed troops in the Americas. Visceral leishmaniasis cases were less frequent, all reported from the Eastern Mediterranean and associated with the Leishmania donovani/infantum complex; whereas CL cases in the Old World were due predominantly to L. major and L. tropica. Regular use of long-lasting insecticidal nets to mitigate sand fly exposure demonstrated high potential effectiveness than other reported personal protective measures (PPMs) which yielded mixed or inconclusive results. In summary, the systematic review revealed the substantial variability between study designs and statistical integrity. There is need for more consistent and robustly designed studies including well-define controls and replication. Future studies would be advised to explore the long-term effectiveness and practicality of PPMs, both individually and in combination, across diverse deployment settings.

Leishmaniasis in Patients With Inflammatory Bowel Disease: A National Multicenter Study of GETECCU

BACKGROUND

Leishmaniasis (LI) is a vector-borne illness caused by a protozoan of the genus Leishmania. Data on the features of LI in patients with inflammatory bowel disease (IBD) are scarce.

AIM

To describe the characteristics of patients with IBD who present with leishmaniasis, infection outcomes and the risk factors associated with developing visceral leishmaniasis (VL).

METHODS

An observational retrospective study performed in 26 hospitals in Spain, including all adult patients with IBD who developed Leishmaniasis from 2012 to 2022.

RESULTS

A total of 73 patients were included [mean age 48 years; 65% male; 68% Crohn's disease]. Sixty patients (82.2%) presented localized cutaneous Leishmaniasis (CL), 2 (2.7%) diffuse CL, 3 (4.1%) mucocutaneous Leishmaniasis (MCL) and 8 (11%) VL. All patients were under biologicals (69 [94.5%]) or immunosuppressants (IMM) (4 [5.5%]) at Leishmaniasis diagnosis. AntiTNF was used in 97%, while 2 patients (3%) were receiving ustekinumab. Leishmaniasis resolution was achieved by 48% and 96% of the patients after 1 and 12 months, respectively. Biological withdrawal after Leishmaniasis diagnosis was not statistically related to increased rates of infection resolution among patients with localized CL. Age was the only risk factor associated with VL (OR 1.2, 95%CI 1.04-1.39; p = 0.012).

CONCLUSIONS

Leishmaniasis in patients with IBD doesn't seem to follow a complicated clinical course, even in those with localized CL who do not discontinue biological therapy after infection diagnosis. Age might be a risk factor for developing VL. This infection should be considered for immunosuppressed patients with IBD and suggestive symptoms dwelling or travelling to endemic areas.

qPCR as a Tool for the Diagnosis of Visceral and Cutaneous Leishmaniasis: A Systematic Review and Meta-Analysis

INTRODUCTION

Ensuring accuracy in the diagnosis of leishmaniasis is crucial due to the myriad of potential differential diagnoses. Given the inherent limitations of serological techniques, real-time polymerase chain reaction (qPCR) emerges as a superior alternative. Furthermore, parasitological methods, conventionally regarded as the gold standard owing to their high specificity, encounter challenges concerning sensitivity and invasiveness for patients. In this context, the present study aims to assess, via meta-analysis, the performance of qPCR in diagnosing visceral and cutaneous leishmaniasis.

METHOD

This meta-analysis encompassed studies published between January 2011 and December 2022, sourced from six databases (PubMed, LILACS, Scopus, Scielo, EMBASE, and Web of Science), utilizing the keywords "qPCR," "molecular diagnosis," and "leishmaniasis." Epidemiological studies focusing on the efficacy of qPCR for leishmaniasis diagnosis were included. Data such as study demographics, geographic locations, sampling techniques, and the number of positive qPCR results were aggregated and analyzed to derive overall positivity rates, sensitivity, and specificity values associated with qPCR. Heterogeneity analysis was conducted on the data to select appropriate models, and the collective efficacy data of qPCR were illustrated in forest plots.

RESULTS

Fifty-four studies met all inclusion criteria. The positivity rates for human visceral and cutaneous leishmaniasis were 27.07% (95% CI: 17.81-36.33%) and 60.40% (95% CI: 30.23-90.57%), respectively. In cases of visceral leishmaniasis in dogs, cats, and wild animals, the positivity rates were 26.55% (95% CI: 21.40-31.70%), 0.92% (95% CI: 0.09-1.75%), and 28.98% (95% CI: 21.86-35.10%), respectively. Analysis of the selected studies revealed high overall sensitivity and specificity values achieved with qPCR, at 91.08% (95% CI: 81.77-100.39%) and 98.08% (95% CI: 97.13-99.03%), respectively.

CONCLUSION

This study indicates that qPCR is a highly sensitive and specific tool, adequately suitable for the diagnosis of human visceral and cutaneous leishmaniasis, as well as visceral leishmaniasis in animals.

A Narrative Review of Molecular, Immunohistochemical and In-Situ Techniques in Dermatopathology

Skin disorders pose a significant health burden globally, affecting millions of individuals across diverse demographics. Advancements in molecular techniques have revolutionised our understanding of the underlying mechanisms of skin disorders, offering insights into their pathogenesis, diagnosis, and potential targeted treatment. Furthermore, the integration of molecular diagnostics into clinical practice has enhanced the accuracy of skin disorder diagnoses. Polymerase chain reaction (PCR), next-generation sequencing (NGS), and other molecular assays have allowed for the detection of infectious agents, assessment of genetic mutations, and profile gene expression patterns with unequalled precision. These techniques have proven instrumental in distinguishing between subtypes of skin cancers, aiding treatment strategies and prognostic assessments. Moreover, molecular profiling is increasingly guiding the selection of therapeutic agents, ensuring a personalised and effective approach to managing skin disorders. The application of PCR has revolutionised the field by enabling the identification of microbial DNA (i.e., Mycobacterium tuberculosis and Epstein-Barr Virus) in skin infections and detecting specific genetic mutations associated with dermatological disorders (e.g., BRAF). DNA sequencing technologies, such as next-generation sequencing, have facilitated the elucidation of genetic variations and mutations in skin diseases (i.e., bullous disorders), paving the way for personalised treatment approaches. Gene expression profiling techniques, such as microarrays and RNA sequencing, have provided insights into dysregulated pathways and molecular signatures associated with conditions ranging from inflammatory skin disorders to cutaneous malignancies. Immunohistochemistry and fluorescence in situ hybridization have proven invaluable in determining protein expression patterns and detecting chromosomal abnormalities, respectively, aiding in the characterization of skin lesions in conjunction with the molecular data. Proteomic studies have contributed to understanding the intricate protein networks involved in dermatological conditions (i.e., psoriasis), while epigenetic analyses have shed light on the role of epigenetic modifications in gene regulation within skin cancer (i.e., Malignant Melanoma). Together, these molecular techniques have laid the groundwork for targeted therapies and precision medicine in dermatology, with implications for improved diagnostics and treatment outcomes. This review focuses on the routinely employed molecular techniques within dermatopathology, with a focus on cutaneous malignancies, autoimmune diseases, infectious diseases, and neonatal screening which can be implemented in the diagnosis and contribute to improved patient care.

Canine leishmaniasis in Maghreb countries: A systematic review and meta-analysis

Canine leishmaniasis (CanL) is a zoonotic disease caused by infection with Leishmania infantum and transmitted by female phlebotomine sandflies. It is prevalent in the Mediterranean basin, including the Maghreb region which comprises of Algeria, Tunisia, and Morocco. The environmental conditions in this area provide a suitable habitat for the proliferation of the phlebotomine sandfly, making it an endemic region for CanL. In this context, we carried out a systematic review and meta-analysis on the prevalence of canine leishmaniasis in these three Maghreb countries, identifying the risk factors for L. infantum infection. Data were collected from 27 papers published between 1973 and 2022 selected from five databases: PubMed, Google Scholar, ResearchGate, ScienceDirect and Scopus. Our selection criteria included both descriptive and analytical studies on canine leishmaniasis in Maghreb, as well as epidemiological studies that reported the prevalence of leishmaniasis infection. The meta-analysis was performed using Review Manager (RevMan) software version 5.4.1. based on predefined inclusion criteria. A total of 11,736 dogs were included in the analysis, among which 2481 were tested Leishmania positive cases. Over the years, the highest prevalence (68.32%) was recorded in Tiaret (Algeria) and the lowest (4.3%) in Tunisia. The examination of the risk factors revealed a heightened incidence of the disease in dogs of shepherd breeds, living in rural environments, displaying no apparent symptoms, and falling within the age range of 2 to 4 years. The findings presented in this study contribute a significant value to the exploration of leishmaniasis in this region, particularly by shedding light on the associated risk factors. Ultimately, substantial endeavors are warranted to enhance prevention, treatment, and overall control of the disease.

Leishmaniasis - Still a diagnostic challenge: An individual participant data systematic review

Leishmania, endemic in nearly half the world's countries, continues to pose significant diagnostic challenges. Our systematic review sought to analyse problems in diagnosis especially in low- to middle-income countries. The average time from symptom onset to diagnosis was 4.5 years. While microscopic detection often failed, polymerase chain reaction showed high sensitivity. Clinical presentations varied significantly, highlighting the complexity of diagnosing leishmaniasis, especially in patients with prolonged disease in non-endemic areas.

Shared challenges to the control of complex intracellular neglected pathogens

The complex intracellular pathogens Mycobacterium tuberculosis, Mycobacterium leprae, Leishmania spp., and Burkholderia pseudomallei, which cause tuberculosis, leprosy, leishmaniasis, and melioidosis respectively, represent major health threats with a significant global burden concentrated in low- and middle-income countries. While these diseases vary in their aetiology, pathology and epidemiology, they share key similarities in the biological and sociodemographic factors influencing their incidence and impact worldwide. In particular, their occurrence in resource-limited settings has important implications for research and development, disease prevalence and associated risk factors, as well as access to diagnostics and therapeutics. In accordance with the vision of the VALIDATE (VAccine deveLopment for complex Intracellular neglecteD pAThogeEns) Network, we consider shared challenges to the effective prevention, diagnosis and treatment of these diseases as shaped by both biological and social factors, illustrating the importance of taking an interdisciplinary approach. We further highlight how a cross-pathogen perspective may provide valuable insights for understanding and addressing challenges to the control of all four pathogens.

Spotlight on Leishmaniasis Research: Insights from the Special Issue "Emerging Topics in Leishmaniasis Research"

Leishmaniases, caused by dixenous trypanosomatids from the Leishmaniinae subfamily (over 20 Leishmania species), manifest in three primary clinical forms: visceral (VL), cutaneous (CL), and mucocutaneous (MCL) [...].

Portable smartphone-based molecular test for rapid detection of Leishmania spp

PURPOSE

Leishmaniasis, caused by the parasite of the genus Leishmania, is a neglected tropical disease which is endemic in more than 60 countries. In South-East Asia, Brazil, and East Africa, it mainly occurs as kala-azar (visceral leishmaniasis, VL), and subsequently as post kala-azar dermal leishmaniasis (PKDL) in a smaller portion of cases. As stated per WHO roadmap, accessibility to accurate diagnostic methods is an essential step to achieve elimination. This study aimed to test the accuracy of a portable minoo device, a small battery-driven, multi-use fluorimeter operating with isothermal technology for molecular diagnosis of VL and PKDL.

METHODS

Fluorescence data measured by the device within 20 min are reported back to the mobile application (or app) via Bluetooth and onward via the internet to a backend. This allows anonymous analysis and storage of the test data. The test result is immediately returned to the app displaying it to the user.

RESULTS

The limit of detection was 11.2 genome copies (95% CI) as determined by screening a tenfold dilution range of whole Leishmania donovani genomes using isothermal recombinase polymerase amplification (RPA). Pathogens considered for differential diagnosis were tested and no cross-reactivity was observed. For its diagnostic performance, DNA extracted from 170 VL and PKDL cases, comprising peripheral blood samples (VL, n = 96) and skin biopsies (PKDL, n = 74) from India (n = 108) and Bangladesh (n = 62), was screened. Clinical sensitivity and specificity were 88% and 91%, respectively.

CONCLUSION

Minoo devices can offer a convenient, cheaper alternative to other molecular diagnostics. Its easy handling makes it ideal for use in low-resource settings to identify parasite burden.

Prevalence of Leishmaniasis among Blood Donors: A Systematic Review and Meta-Analysis

Our study seeks to provide a comprehensive assessment of leishmaniasis prevalence among blood donors, employing rigorous methodologies to inform public health initiatives and transfusion safety measures. A thorough literature search was conducted using electronic databases (Medline, Scopus, Web of Science, and Google Scholar) to identify the relevant studies reporting the prevalence of leishmaniasis among blood donors, gathering a wide range of studies encompassing different geographic locations and time periods. The pooled prevalence with a 95% confidence interval (CI) was estimated, and quality assessment, outlier analysis, and influential analysis were performed to ensure the robustness and validity of the findings. Our search and subsequent analyses led to the inclusion of thirty-five studies in our review. Using molecular diagnostic methods, the prevalence was estimated at 2.3% (95% CI 1-3.9%), while serological diagnostic methods indicated a higher prevalence rate of 4.5% (95% CI 2.8-6.7%). Notably, we observed significant heterogeneity among the included studies for each analysis. The observed heterogeneity highlights the need for future research to delve into the factors influencing leishmaniasis prevalence, with prospective and retrospective studies addressing the limitations identified in this review.

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.

Development of a low-cost robotized 3D-prototype for automated optical microscopy diagnosis: An open-source system

In a clinical context, conventional optical microscopy is commonly used for the visualization of biological samples for diagnosis. However, the availability of molecular techniques and rapid diagnostic tests are reducing the use of conventional microscopy, and consequently the number of experienced professionals starts to decrease. Moreover, the continuous visualization during long periods of time through an optical microscope could affect the final diagnosis results due to induced human errors and fatigue. Therefore, microscopy automation is a challenge to be achieved and address this problem. The aim of the study is to develop a low-cost automated system for the visualization of microbiological/parasitological samples by using a conventional optical microscope, and specially designed for its implementation in resource-poor settings laboratories. A 3D-prototype to automate the majority of conventional optical microscopes was designed. Pieces were built with 3D-printing technology and polylactic acid biodegradable material with Tinkercad/Ultimaker Cura 5.1 slicing softwares. The system's components were divided into three subgroups: microscope stage pieces, storage/autofocus-pieces, and smartphone pieces. The prototype is based on servo motors, controlled by Arduino open-source electronic platform, to emulate the X-Y and auto-focus (Z) movements of the microscope. An average time of 27.00 ± 2.58 seconds is required to auto-focus a single FoV. Auto-focus evaluation demonstrates a mean average maximum Laplacian value of 11.83 with tested images. The whole automation process is controlled by a smartphone device, which is responsible for acquiring images for further diagnosis via convolutional neural networks. The prototype is specially designed for resource-poor settings, where microscopy diagnosis is still a routine process. The coalescence between convolutional neural network predictive models and the automation of the movements of a conventional optical microscope confer the system a wide range of image-based diagnosis applications. The accessibility of the system could help improve diagnostics and provide new tools to laboratories worldwide.

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

BACKGROUND

Leishmaniasis 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.

METHODS

Stained 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.

RESULTS

The fine-tuned YOLOV5 outperformed the other models such as Faster RCNN and SSD, with the MAP scores, of 73%, 54% and 57%, respectively.

CONCLUSION

The 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.

Simplified molecular diagnosis of visceral leishmaniasis: Laboratory evaluation of miniature direct-on-blood PCR nucleic acid lateral flow immunoassay

BACKGROUND

Diagnosis of visceral leishmaniasis (VL) in resource-limited endemic regions is currently based on serological testing with rK39 immunochromatographic tests (ICTs). However, rK39 ICT frequently has suboptimal diagnostic accuracy. Furthermore, treatment monitoring and detection of VL relapses is reliant on insensitive and highly invasive tissue aspirate microscopy. Miniature direct-on-blood PCR nucleic acid lateral flow immunoassay (mini-dbPCR-NALFIA) is an innovative and user-friendly molecular tool which does not require DNA extraction and uses a lateral flow strip for result read-out. This assay could be an interesting candidate for more reliable VL diagnosis and safer test of cure at the point of care.

METHODOLOGY/PRINCIPLE FINDINGS

The performance of mini-dbPCR-NALFIA for diagnosis of VL in blood was assessed in a laboratory evaluation and compared with the accuracy of rK39 ICTs Kalazar Detect in Spain and IT LEISH in East Africa. Limit of detection of mini-dbPCR-NALFIA was 650 and 500 parasites per mL of blood for Leishmania donovani and Leishmania infantum, respectively. In 146 blood samples from VL-suspected patients from Spain, mini-dbPCR-NALFIA had a sensitivity of 95.8% and specificity 97.2%, while Kalazar Detect had a sensitivity of 71.2% and specificity of 94.5%, compared to a nested PCR reference. For a sample set from 58 VL patients, 10 malaria patients and 68 healthy controls from Ethiopia and Kenya, mini-dbPCR-NALFIA had a pooled sensitivity of 87.9% and pooled specificity of 100% using quantitative PCR as reference standard. IT LEISH sensitivity and specificity in the East African samples were 87.9% and 97.4%, respectively.

CONCLUSIONS/SIGNIFICANCE

Mini-dbPCR-NALFIA is a promising tool for simplified molecular diagnosis of VL and follow-up of treated patients in blood samples. Future studies should evaluate its use in endemic, resource-limited settings, where mini-dbPCR-NALFIA may provide an accurate and versatile alternative to rK39 ICTs and aspirate microscopy.

Quinine and chloroquine: Potential preclinical candidates for the treatment of tegumentary Leishmaniasis

Leishmaniasis is an endemic disease in more than 90 countries, constituting a relevant public health problem. Limited treatment options, increase in resistance, and therapeutic failure are important aspects for the discovery of new treatment options. Drug repurposing may accelerate the discovery of antiLeishmanial drugs. Recent tests indicating the in vitro potential of antimalarials Leishmania resulted in the design of this study. This study aimed at evaluating the susceptibility of Leishmania (L.) amazonensis to chloroquine (CQ) and quinine (QN), alone or in combination with amphotericin B (AFT) and pentamidine (PTN). In the in vitro tests, first, we evaluated the growth inhibition of 50 % of promastigotes (IC50) and cytotoxicity for HepG2 and THP-1 cells (CC50). The IC50 values of AFT and PNT were below 1 µM, while the IC50 values of CQ and QN ranged between 4 and 13 µM. Concerning cytotoxicity, CC50 values ranged between 7 and 30 µM for AFT and PNT, and between 22 and 157 µM for the antimalarials. We also calculated the Selectivity Index (SI), where AFT and PTN obtained the highest values, while the antimalarias obtained values between 5 and 12. Both antimalarials were additive (ƩFIC 1.05-1.8) in combination with AFT and PTN. For anti-amastigote activity, the drugs obtained the following ICA50 values: AFT (0.26 µM), PNT (2.09 µM), CQ (3.77 µM) and QN (24.5 µM). In the in vivo tests, we observed that the effective dose for the death of 50 % of parasites (ED50) of AFT and CQ were 0.63 mg/kg and 27.29 mg/kg, respectively. When combining CQ with AFT, a decrease in parasitemia was observed, being statistically equal to the naive group. For cytokine quantification, it was observed that CQ, despite presenting anti-inflammatory activity was effective at increasing the production of IFN-γ. Overall, our data indicate that chloroquine will probably be a candidate for repurposing and use in drug combination therapy.

Diagnosis of Cutaneous Leishmaniasis Using FTIR Spectroscopy and Machine Learning: An Animal Model Study

Cutaneous leishmaniasis (CL) is a polymorphic and spectral skin disease caused by Leishmania spp. protozoan parasites. CL is difficult to diagnose because conventional methods are time-consuming, expensive, and low-sensitive. Fourier transform infrared spectroscopy (FTIR) with machine learning (ML) algorithms has been explored as an alternative to achieve fast and accurate results for many disease diagnoses. Besides the high accuracy demonstrated in numerous studies, the spectral variations between infected and noninfected groups are too subtle to be noticed. Since variability in sample set characteristics (such as sex, age, and diet) often leads to significant data variance and limits the comprehensive understanding of spectral characteristics and immune responses, we investigate a novel methodology for diagnosing CL in an animal model study. Blood serum, skin lesions, and draining popliteal lymph node samples were collected from Leishmania (Leishmania) amazonensis-infected BALB/C mice under experimental conditions. The FTIR method and ML algorithms accurately differentiated between infected (CL group) and noninfected (control group) samples. The best overall accuracy (∼72%) was obtained in an external validation test using principal component analysis and support vector machine algorithms in the 1800-700 cm-1 range for blood serum samples. The accuracy achieved in analyzing skin lesions and popliteal lymph node samples was satisfactory; however, notable disparities emerged in the validation tests compared to results obtained from blood samples. This discrepancy is likely attributed to the elevated sample variability resulting from molecular compositional differences. According to the findings, the successful functioning of prediction models is mainly related to data analysis rather than the differences in the molecular composition of the samples.

Case Report: In Situ and Systemic Immune Response to Mucosal Leishmaniasis in an HIV-Infected Patient

In situ and systemic evaluations of the immune responses of HIV-infected patients to mucosal leishmaniasis have been poorly described. We describe a recently diagnosed HIV-infected patient with mucosal leishmaniasis who was characterized by a CD4 count of 85 cells/mm3 and nasal septum destruction resulting from pruritic and ulcerated nasal mucosa with crust formation and progression over 2 years. In situ and systemic immune evaluations of T cell activation, memory, and exhaustion were conducted using cytofluorometric assays, and sequencing of the Leishmania species was performed. The immune profile of HIV-infected patient with mucosal leishmaniasis shows a mixed Th1/Th2 pattern and an activated and exhausted status.

The need for culture in tegumentary leishmaniasis diagnosis in Bolivia: A comparative evaluation of four parasitological techniques using two sampling methods

Leishmaniases are zoonotic diseases caused by protozoa of the genus Leishmania. In Bolivia, leishmaniasis occurs mainly in the cutaneous form (CL) followed by the mucosal or mucocutaneous form (ML or MCL), grouped as tegumentary leishmaniosis (TL), while cases of visceral leishmaniasis (VL) are rare. The cases of TL are routinely diagnosed by parasitological methods: Direct Parasitological Exam (DPE) and axenic culture, the latter being performed only by specialized laboratories. The aim of the present study was to optimize the parasitological diagnosis of TL in Bolivia, using two sampling methods. Samples from 117 patients with suspected TL, obtained by aspiration (n = 121) and scraping (n = 121) of the edge of the lesion were tested by: direct parasitological exam, culture in TSTB medium, and miniculture and microculture in Schneider's medium. A positive laboratory result by any of the four techniques evaluated using either of the two sampling methods was considered the gold standard. Of the 117 suspected patients included, TL was confirmed in 96 (82 %), corresponding 79 of the confirmed cases (82.3 %) to CL and 16 (16.7 %) to ML. Parasitological techniques specificity was 100 % and their analytical sensitivity was greater with scraping samples in TSTB culture (98 %). Scraping samples in TSTB and miniculture correlated well with the reference (Cohen's kappa coefficient=0.88) and showed good reliability (Cronbach's alpha coefficient ≥0.91). Microculture provided positive results earlier than the other culture methods (mean day 4.5). By day 14, 98 % of positive cultures had been detected. Scraping sampling and miniculture were associated with higher culture contamination (6 % and 17 %, respectively). Bacterial contamination predominated, regardless of the sampling and culture method, while filamentous fungi and mixed contamination were more frequently observed in cultures from scraping samples. In conclusion: (i) scraping samples proved more suitable for the diagnosis of TL as they increased analytical sensitivity, are less traumatic for the patient and are safer for laboratory personnel than aspirates; (ii) culture, mainly in TSBT medium, should be used for the diagnosis of TL due to its high sensitivity (doubling the number of cases diagnosed by DPE) and its low cost compared to other culture media.

A Review on the use of Synthetic and Recombinant Antigens for the Immunodiagnosis of Tegumentary Leishmaniasis

Improving the diagnostic technology used to detect tegumentary leishmaniasis (TL) is essential in view of it being a widespread, often neglected tropical disease, with cases reported from the Southern United States to Northern Argentina. Recombinant proteins, recombinant multiepitope proteins, and synthetic peptides have been extensively researched and used in disease diagnosis. One of the benefits of applying these antigens is a measurable increase in sensitivity and specificity, which improves test accuracy. The present review aims to describe the use of these antigens and their diagnostic effectiveness. With that in mind, a bibliographic survey was conducted on the PudMed platform using the search terms "tegumentary leishmaniasis" AND "diagno", revealing that recombinant proteins have been described and evaluated for their value in TL diagnosis since the 1990s. However, there was a spike in the number of publications using all of the antigens between 2013 and 2022, confirming an expansion in research efforts to improve diagnosis. Moreover, all of the studies involving different antigens had promising results, including improved sensitivity and specificity. These data recognize the importance of doing research with new technologies focused on developing quick, more effective diagnostic kits as early diagnosis facilitates treatment.

Evaluation of the Diagnostic Sensitivity of the VIASURE Leishmania Real-Time PCR Detection Kit Prototype for the Diagnosis of Cutaneous and Visceral Leishmaniasis

Leishmaniasis is a parasitic disease with clinical presentations that vary from asymptomatic infection to cutaneous, mucocutaneous, or visceral disease. Global change, with migratory movements and travels, among others, has had an impact on the presentation of the clinical forms of leishmaniasis in a given area, hindering its diagnosis. The traditional parasitological techniques have limited sensitivity, and currently, there is no reference or gold-standard molecular diagnostic method. The aim of this study was to evaluate the effectivity of the VIASURE Leishmania Real-Time PCR Detection Kit prototype (CerTest Biotec, Zaragoza, Spain) for the diagnosis of autochthonous and imported leishmaniasis in comparison with two other commercialized molecular kits: STAT-NAT® Leishmania spp. (Sentinel, Milano, Italy) and Leishmania spp. Real-TM PCR Kit (Sacace Biotechnologies, Como, Italy). Four species of Leishmania, L. infantum, L. major, L. braziliensis, and L. panamensis, were targeted to assess analytical sensitivity, whereas diagnostic sensitivity was evaluated by studying a panel of 49 DNA samples from patients with suspected or confirmed Leishmania infection. The prototype could detect all the New and Old World species studied and achieved a limit of detection of 5 × 10-5 ng DNA/μL in all species. Also, it allowed the diagnosis of autochthonous and imported cases of cutaneous and visceral leishmaniasis (VL). Diagnostic sensitivity was 81.8% for the prototype and 100% for the Sacace kit (27 and 33 positive samples detected, respectively). The STAT-NAT® kit failed to detect Vianna species. The VIASURE Leishmania Real-Time PCR Detection Kit prototype was found to have good analytical and diagnostic sensitivity. Using a simple protocol and ready-to-use reagents, results are obtained quickly and are easy to interpret. The evaluation results indicate that the test is a promising candidate for routine diagnosis of cutaneous leishmaniasis and VL in endemic countries, but more studies are necessary to address its sensitivity and specificity.

Evaluation of a Point-of-Need Molecular Diagnostic Tool Coupled with Rapid DNA Extraction Methods for Visceral Leishmaniasis

A rapid, cost-effective, and simple nucleic acid isolation technique coupled with a point-of-need DNA amplification assay is a desirable goal for programmatic use. For diagnosis of Visceral Leishmaniasis (VL), Recombinase Polymerase Amplification (RPA) rapid tests for the detection of Leishmania DNA are versatile and have operational advantages over qPCR. To facilitate the delivery of the RPA test at point-of-need for VL diagnosis, we compared two rapid DNA extraction methods, SwiftDx (SX) and an in-house Boil and Spin (BS) method, coupled with RPA amplification, versus more widely used methods for DNA extraction and amplification, namely Qiagen (Q) kits and qPCR, respectively. A total of 50 confirmed VL patients and 50 controls, matched for age and gender, were recruited from Mymensingh, Bangladesh, a region highly endemic for VL. Blood samples were collected from each participant and DNA was extracted using Q, SX and BS methods. Following DNA extraction, qPCR and RPA assays were performed to detect L. donovani in downstream analysis. No significant differences in sensitivity of the RPA assay were observed between DNA extraction methods, 94.00% (95% CI: 83.45-98.75%), 90% (95% CI: 78.19-96.67%), and 88% (95% CI: 75.69-95.47%) when using Q, SX, and BS, respectively. Similarly, using qPCR, no significant differences in sensitivity were obtained when using Q or SX for DNA extraction, 94.00% (95% CI: 83.45-98.75%) and 92.00% (80.77-97.78%), respectively. It is encouraging that RPA and qPCR showed excellent agreement (k: 0.919-0.980) when different extraction methods were used and that the DNA impurities using BS had no inhibitory effect on the RPA assay. Furthermore, significantly higher DNA yields were obtained using SX and BS versus Q; however, a significantly higher parasite load was detected using qPCR when DNA was extracted using Q versus SX. Considering the cost, execution time, feasibility, and performance of RPA assay, rapid extraction methods such as the Boil and Spin technique appear to have the potential for implementation in resource-limited endemic settings. Further clinical research is warranted prior to broader application.

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.

Sensitivity of PCR in conjunctival swab samples for the diagnosis of canine visceral leishmaniasis: a systematic review and meta-analysis

To compare the sensitivity of conjunctival swab (CS) and conventional samples (blood, spleen, liver, lymphoid and cutaneous tissue) in the diagnosis of canine visceral leishmaniasis (CVL) by polymerase chain reaction (PCR), a systematic review and meta-analysis was carried out using PubMed, Science Direct, Scopus, Web of Science, VHL/BVS (Virtual Health Library), CAPES, and Scielo databases. Articles published from 2002 to 2022 were considered and the review was updated in Jul 2023. From the total of 371 identified studies, 8 met all the eligibility criteria and were included in this review. Data from 658 CVL-positive dogs and 2541 PCR results were considered. Using a random effect model, data on the sensitivity of the test was compared between intervention (CS samples) and comparison (all the other samples) groups. Overall, the use of CS in the PCR diagnosis of CVL produced 12% higher sensitivity (p=0.013) in the test than all the other samples in combination. The animals' clinical condition did not influence (p>0.142) this overall result. However, when CS was individually compared to each of the conventional samples, the consistent result was observed (p=0.012) only in the CS versus bone marrow comparison. Given their rapid acquisition, minimal invasiveness, and lower cost relative to conventional samples, CS samples present a promising alternative for the molecular diagnosis of CVL.

Accuracy of the direct agglutination test for diagnosis of visceral leishmaniasis: a systematic review and meta-analysis

BACKGROUND

Parasitological investigation of bone marrow, splenic or lymph node aspirations is the gold standard for the diagnosis of visceral leishmaniasis (VL). However, this invasive test requires skilled clinical and laboratory staff and adequate facilities, and sensitivity varies depending on the tissue used. The direct agglutination test (DAT) is a serological test that does not need specialised staff, with just minimal training required. While previous meta-analysis has shown DAT to have high sensitivity and specificity when using parasitology as the reference test for diagnosis, meta-analysis of DAT compared to other diagnostic techniques, such as PCR and ELISA, that are increasingly used in clinical and research settings, has not been done.

METHODS

We conducted a systematic review to determine the diagnostic performance of DAT compared to all available tests for the laboratory diagnosis of human VL. We searched electronic databases including Medline, Embase, Global Health, Scopus, WoS Science Citation Index, Wiley Cochrane Central Register of Controlled Trials, Africa-Wide Information, LILACS and WHO Global Index. Three independent reviewers screened reports and extracted data from eligible studies. A meta-analysis estimated the diagnostic sensitivity and specificity of DAT.

RESULTS

Of 987 titles screened, 358 were selected for full data extraction and 78 were included in the analysis, reporting on 32,822 participants from 19 countries. Studies included were conducted between 1987-2020. Meta-analysis of studies using serum and DAT compared to any other test showed pooled sensitivity of 95% (95%CrI 90-98%) and pooled specificity of 95% (95%CrI 88-98%). Results were similar for freeze-dried DAT and liquid DAT when analysed separately. Sensitivity was lower for HIV-positive patients (90%, CrI 59-98%) and specificity was lower for symptomatic patients (70%, CrI 43-89%). When comparing different geographical regions, the lowest median sensitivity (89%, CrI 67-97%) was in Western Asia (five studies).

CONCLUSIONS

This systematic review and meta-analysis demonstrates high estimated pooled sensitivity and specificity of DAT for diagnosis of VL, although sensitivity and specificity were lower for different patient groups and geographical locations. This review highlights the lack of standardisation of DAT methods and preparations, and the lack of data from some important geographical locations. Future well-reported studies could provide better evidence to inform test implementation for different patient populations and use cases.

PROSPERO REGISTRATION

CRD42021240830.

Vaccine value profile for leishmaniasis

Leishmania infections are global, occurring in 98 countries and all World Health Organization (WHO) regions with 600 million to 1 billion people at risk of infection. Visceral leishmaniasis is associated with almost 20,000 reported deaths annually, with children under 5 years of age being at the greatest risk of mortality. Amongst WHO-recognised Neglected Tropical Diseases (NTDs), leishmaniasis is one of the most important in terms of mortality and morbidity. With an increasing global burden of disease and a growing threat from climate change, urbanisation and drug resistance, there remains an imperative to develop leishmaniasis vaccines. New tools to understand correlates of protection and to assess vaccine efficacy are being developed to ease the transition into larger scale efficacy trials or provide alternate routes to licensure. Early indications suggest a diverse portfolio of manufacturers exists in endemic countries with an appetite to develop leishmaniasis vaccines. This Vaccine Value Profile (VVP) provides a high-level, comprehensive assessment of the currently available data to inform the potential public health, economic, and societal value of leishmaniasis vaccines. The leishmaniasis VVP was developed by a working group of subject matter experts from academia, public health groups, policy organizations, and non-profit organizations. All contributors have extensive expertise on various elements of the leishmaniasis VVP and have collectively described the state of knowledge and identified the current gaps. The VVP was developed using only existing and publicly available information.

Developments in Leishmaniasis diagnosis: A patent landscape from 2010 to 2022

The current study aims to contribute to the understanding of leishmaniasis diagnosis by providing an overview of patent filings in this field and analyzing whether the methods revealed are consistent with the needs described by the scientific community, in special the main gaps detected by the World Health Organization's 2021-2030 Roadmap for Neglected Tropical Diseases. To this aim, a patent search was carried out focusing on documents disclosing leishmaniasis diagnostic methods supported by experimental evidence and with earliest priority date from 2010 onwards. Our results show that patenting activity is low and patent families are often formed by individual filings. Most R&D activity occurs in Brazil, which is also the main market of protection. Brazilian academic institutions are the main patent drivers, and collaboration between different institutions is rare. Most patent families describe immunological methods based on ELISA assays, using antibodies directed to K39 and homologues. kDNA is the primary gene for molecular testing. Experimental evidence of test performance in fulfilling critical diagnostic gaps is usually absent. The patent scenario suggests that leishmaniasis diagnostic gaps need to be more closely addressed to drive innovation directed to the control and/or elimination of leishmaniasis. From the public policy point of view, the following strategies are suggested: (i) strengthening collaborative networks, (ii) enhancing the participation of the private sector, and (iii) increasing funding, with special focus on the remaining diagnostic gaps.

Parasite Detection in Visceral Leishmaniasis Samples by Dye-Based qPCR Using New Gene Targets of Leishmania infantum and Crithidia

Visceral leishmaniasis (VL) is a neglected disease considered a serious public health problem, especially in endemic countries. Several studies have discovered monoxenous trypanosomatids (Leptomonas and Crithidia) in patients with VL. In different situations of leishmaniasis, investigations have examined cases of co-infection between Leishmania spp. and Crithidia spp. These coinfections have been observed in a wide range of vertebrate hosts, indicating that they are not rare. Diagnostic techniques require improvements and more robust tools to accurately detect the causative agent of VL. This study aimed to develop a real-time quantitative dye-based PCR (qPCR) assay capable of distinguishing Leishmania infantum from Crithidia-related species and to estimate the parasite load in samples of VL from humans and animals. The primer LinJ31_2420 targets an exclusive phosphatase of L. infantum; the primer Catalase_LVH60-12060_1F targets the catalase gene of Crithidia. Therefore, primers were designed to detect L. infantum and Crithidia sp. LVH60A (a novel trypanosomatid isolated from VL patients in Brazil), in samples related to VL. These primers were considered species-specific, based on sequence analysis using genome data retrieved from the TriTryp database and the genome assembling of Crithidia sp. LVH60A strain, in addition to experimental and clinical data presented herein. This novel qPCR assay was highly accurate in identifying and quantifying L. infantum and Crithidia sp. LVH60A in samples obtained experimentally (in vitro and in vivo) or collected from hosts (humans, dogs, cats, and vectors). Importantly, the screening of 62 cultured isolates from VL patients using these primers surprisingly revealed that 51 parasite cultures were PCR+ for Crithidia sp. In addition, qPCR assays identified the co-infection of L. infantum with Crithidia sp. LVH60A in two new VL cases in Brazil, confirming the suspicion of co-infection in a previously reported case of fatal VL. We believe that the species-specific genes targeted in this study can be helpful for the molecular diagnosis of VL, as well as for elucidating suspected co-infections with monoxenous-like trypanosomatids, which is a neglected fact of a neglected disease.

The Accuracy of Diagnosis and Genotyping of Leishmania Species Based on Spliced Leader Mini-Exon Gene by Nuclear Magnetic Resonance and Sequencing Assays

Background

We aimed to evaluate the accuracy of genotyping of Leishmania species by the spliced leader mini-exon gene.

Methods

Suspected leishmaniasis patients, referred to Masieh Daneshvary Hospital, Tehran, Iran were included from May 2017 to September 2021. The Leishmania species were genotyped by PCRRFLP based on the SL mini-exon gene and the ITS1 region of SSU-rRNA gene and compared with the sequencing results. The expressed metabolites of metacyclic promastigotes were evaluated by Proton nuclear magnetic resonance (1H-NMR).

Results

Out of 66 suspected cases, 36 (54.4%) were positive for Leishmania species based on the PCR assays. In 21 (31.8%) cases, promastigotes grew on culture tubes. Based on the RFLP of SL RNA profile, 13 (19.7%) L. tropica, 9 (13.6%) L. major, 3 (4.5%) L. infantum, and 8 (12.1%) C. fasciculata isolates, isolated from culture media, were identified; however, 3 (4.5%) cases were unidentifiable due to the low number of parasites. Seventeen metabolites were expressed by the metacyclic forms of L. major, L. tropica and C. fasciculata isolates. The top differential metabolites expressed more in C. fasciculata were FAD, p-Methoxybenzyl alcohol and S-b-G-5, 5-G-b-S (A = CH2) (P<0.005) whereas Veratryl glycerols and D-(+)-Mannose were significantly increased in L. major and Betulin, LTyrosine in L. tropica (P<0.01).

Conclusion

The invaluable techniques such as sequencing and 1H-NMR confirmed the results of genotyping of Leishmania species based on the SL mini-exon gene. SL mini exon gene can be used as a diagnostic tool to differentiate various Leishmania genotypes and detect contamination of culture media with C. fasciculata.

Metallic Nanoparticles and Core-Shell Nanosystems in the Treatment, Diagnosis, and Prevention of Parasitic Diseases

The usage of nanotechnology in the fight against parasitic diseases is in the early stages of development, but it brings hopes that this new field will provide a solution to target the early stages of parasitosis, compensate for the lack of vaccines for most parasitic diseases, and also provide new treatment options for diseases in which parasites show increased resistance to current drugs. The huge physicochemical diversity of nanomaterials developed so far, mainly for antibacterial and anti-cancer therapies, requires additional studies to determine their antiparasitic potential. When designing metallic nanoparticles (MeNPs) and specific nanosystems, such as complexes of MeNPs, with the shell of attached drugs, several physicochemical properties need to be considered. The most important are: size, shape, surface charge, type of surfactants that control their dispersion, and shell molecules that should assure specific molecular interaction with targeted molecules of parasites' cells. Therefore, it can be expected that the development of antiparasitic drugs using strategies provided by nanotechnology and the use of nanomaterials for diagnostic purposes will soon provide new and effective methods of antiparasitic therapy and effective diagnostic tools that will improve the prevention and reduce the morbidity and mortality caused by these diseases.

Identification of molecular mechanisms causing skin lesions of cutaneous leishmaniasis using weighted gene coexpression network analysis (WGCNA)

Leishmaniasis is an infectious disease, caused by a protozoan parasite. Its most common form is cutaneous leishmaniasis, which leaves scars on exposed body parts from bites by infected female phlebotomine sandflies. Approximately 50% of cases of cutaneous leishmaniasis fail to respond to standard treatments, creating slow-healing wounds which cause permanent scars on the skin. We performed a joint bioinformatics analysis to identify differentially expressed genes (DEGs) in healthy skin biopsies and Leishmania cutaneous wounds. DEGs and WGCNA modules were analyzed based on the Gene Ontology function, and the Cytoscape software. Among almost 16,600 genes that had significant expression changes on the skin surrounding Leishmania wounds, WGCNA determined that one of the modules, with 456 genes, has the strongest correlation with the size of the wounds. Functional enrichment analysis indicated that this module includes three gene groups with significant expression changes. These produce tissue-damaging cytokines or disrupt the production and activation of collagen, fibrin proteins, and the extracellular matrix, causing skin wounds or preventing them from healing. The hub genes of these groups are OAS1, SERPINH1, and FBLN1 respectively. This information can provide new ways to deal with unwanted and harmful effects of cutaneous leishmaniasis.

The leishmaniases in Kenya: A scoping review

BACKGROUND

The leishmaniases are a group of four vector-borne neglected tropical diseases caused by 20 species of protozoan parasites of the genus Leishmania and transmitted through a bite of infected female phlebotomine sandflies. Endemic in over 100 countries, the four types of leishmaniasis-visceral leishmaniasis (VL) (known as kala-azar), cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), and post-kala-azar dermal leishmaniasis (PKDL)-put 1.6 billion people at risk. In Kenya, the extent of leishmaniasis research has not yet been systematically described. This knowledge is instrumental in identifying existing research gaps and designing appropriate interventions for diagnosis, treatment, and elimination.

METHODOLOGY/PRINCIPAL FINDINGS

This study used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology to determine the state of leishmaniases research in Kenya and identify research gaps. We searched seven online databases to identify articles published until January 2022 covering VL, CL, MCL, and/or PKDL in Kenya. A total of 7,486 articles were found, of which 479 underwent full-text screening, and 269 met our eligibility criteria. Most articles covered VL only (n = 141, 52%), were published between 1980 and 1994 (n = 108, 39%), and focused on the theme of "vectors" (n = 92, 34%). The most prevalent study types were "epidemiological research" (n = 88, 33%) tied with "clinical research" (n = 88, 33%), then "basic science research" (n = 49, 18%) and "secondary research" (n = 44, 16%).

CONCLUSION/SIGNIFICANCE

While some studies still provide useful guidance today, most leishmaniasis research in Kenya needs to be updated and focused on prevention, co-infections, health systems/policy, and general topics, as these themes combined comprised less than 4% of published articles. Our findings also indicate minimal research on MCL (n = 1, <1%) and PKDL (n = 2, 1%). We urge researchers to renew and expand their focus on these neglected diseases in Kenya.

Development of a novel immunoFET technology-based POC assay for detection of Leishmania donovani and Leishmania major

Leishmaniasis is considered as one of the 20 neglected tropical diseases. Current methods of leishmanial diagnosis depend on conventional laboratory-based techniques, which are time-consuming, costly and require special equipment and trained personnel. In this context, we aimed to provide an immuno field effect transistors (ImmunoFET) biosensor that matches the conventional standards for point-of-care (POC) monitoring and detection of Leishmania (L.) donovani/Leishmania major. Crude antigens prepared by repeated freeze thawing of L. donovani/L. major stationary phase promastigotes were used for ELISA and ImmunoFETs. Lesishmania-specific antigens were serially diluted in 1× PBS from a concentration of 10⁶ -10² parasites/mL. A specific polyclonal antibody-based sandwich ELISA was established for the detection of Leishmania antigens. An immunoFET technology-based POC novel assay was constructed for the detection of Leishmania antigens. Interactions between antigen-antibody at the gate surface generate an electrical signal that can be measured by semiconductor field-effect principles. Sensitivity was considered and measured as the change in current divided by the initial current. The final L. donovani/L. major crude antigen protein concentrations were measured as 1.50 mg/mL. Sandwich ELISA against the Leishmania 40S ribosomal protein detected Leishmania antigens could detect as few as 100 L. donovani/L. major parasites. An immunoFET biosensor was constructed based on the optimization of aluminium gallium nitride/gallium nitride (AlGaN/GaN) surface oxidation methods. The device surface was composed by an AlGaN/GaN wafer with a 23 nm AlGaN barrier layer, a 2 μm GaN layer on the silicon carbide (SiC) substrate for Leishmania binding, and coated with a specific antibody against the Leishmania 40S ribosomal protein, which was successfully detected at concentrations from 10⁶ to 10² parasites/mL in 1× PBS. At the concentration of 10⁴ parasites, the immunoFETs device sensitivities were 13% and 0.052% in the sub-threshold regime and the saturation regime, respectively. Leishmania parasites were successfully detected by the ImmunoFET biosensor at a diluted concentration as low as 150 ng/mL. In this study, the developed ImmunoFET biosensor performed well. ImmunoFET biosensors can be used as an alternative diagnostic method to ELISA. Increasing the sensitivity and optimization of immuno-FET biosensors might allow earlier and faster detection of leishmaniasis.

Next-Generation Leishmanization: Revisiting Molecular Targets for Selecting Genetically Engineered Live-Attenuated Leishmania

Despite decades of research devoted to finding a vaccine against leishmaniasis, we are still lacking a safe and effective vaccine for humans. Given this scenario, the search for a new prophylaxis alternative for controlling leishmaniasis should be a global priority. Inspired by leishmanization-a first generation vaccine strategy where live L. major parasites are inoculated in the skin to protect against reinfection-live-attenuated Leishmania vaccine candidates are promising alternatives due to their robust elicited protective immune response. In addition, they do not cause disease and could provide long-term protection upon challenge with a virulent strain. The discovery of a precise and easy way to perform CRISPR/Cas-based gene editing allowed the selection of safer null mutant live-attenuated Leishmania parasites obtained by gene disruption. Here, we revisited molecular targets associated with the selection of live-attenuated vaccinal strains, discussing their function, their limiting factors and the ideal candidate for the next generation of genetically engineered live-attenuated Leishmania vaccines to control leishmaniasis.

Recombinant protein KR95 as an alternative for serological diagnosis of human visceral leishmaniasis in the Americas

In the Americas, visceral leishmaniasis (VL) is caused by the protozoan Leishmania infantum, leading to death if not promptly diagnosed and treated. In Brazil, the disease reaches all regions, and in 2020, 1,933 VL cases were reported with 9.5% lethality. Thus, an accurate diagnosis is essential to provide the appropriate treatment. Serological VL diagnosis is based mainly on immunochromatographic tests, but their performance may vary by location, and evaluation of diagnostic alternatives is necessary. In this study, we aimed to evaluate the performance of ELISA with the scantily studied recombinant antigens, K18 and KR95, comparing their performance with the already known rK28 and rK39. Sera from parasitologically confirmed symptomatic VL patients (n = 90) and healthy endemic controls (n = 90) were submitted to ELISA with rK18 and rKR95. Sensitivity (95% CI) was, respectively, 83.3% (74.2-89.7) and 95.6% (88.8-98.6), and specificity (95% CI) was 93.3% (85.9-97.2) and 97.8% (91.8-99.9). For validation of ELISA with the recombinant antigens, we included samples from 122 VL patients and 83 healthy controls collected in three regions in Brazil (Northeast, Southeast, and Midwest). When comparing the results obtained with the VL patients' samples, significantly lower sensitivity was obtained by rK18-ELISA (88.5%, 95% CI: 81.5-93.2) compared with rK28-ELISA (95.9%, 95% CI: 90.5-98.5), but the sensitivity was similar comparing rKR95-ELISA (95.1%, 95% CI: 89.5-98.0), rK28-ELISA (95.9%, 95% CI: 90.5-98.5), and rK39-ELISA (94.3%, 95% CI: 88.4-97.4). Analyzing the specificity, it was lowest with rK18-ELISA (62.7%, 95% CI: 51.9-72.3) with 83 healthy control samples. Conversely, higher and similar specificity was obtained by rKR95-ELISA (96.4%, 95% CI: 89.5-99.2), rK28-ELISA (95.2%, 95% CI: 87.9-98.5), and rK39-ELISA (95.2%, 95% CI: 87.9-98.5). There was no difference in sensitivity and specificity across localities. Cross-reactivity assessment, performed with sera of patients diagnosed with inflammatory disorders and other infectious diseases, was 34.2% with rK18-ELISA and 3.1% with rKR95-ELISA. Based on these data, we suggest using recombinant antigen KR95 in serological assays for VL diagnosis.

RNA-seq analysis of differentially expressed LncRNAs from leishmaniasis patients compared to uninfected humans

Leishmaniasis is a parasitic disease that seriously endangers human health. Furthermore, among the parasitic diseases, leishmaniasis is the third most common cause of death after malaria and schistosomiasis. However, the potential function of LncRNAs in leishmaniasis remain unclear. This study aimed to explore the differentially expressed LncRNAs in leishmaniasis. The sera of leishmaniasis patients and uninfected persons for controls were obtained and analyzed by high-throughput sequencing. Moreover, the expression of key LncRNAs was detected by qPCR. The results showed that 970 differentially expressed LncRNAs and 1692 differentially expressed mRNAs were screened compared to control groups. Then, 520 target genes were identified by using bioinformation analysis and the ENCORI database. The bioinformatics analysis revealed that the differentially expressed target genes were enriched in autophagy animal, FoxO signaling pathway, mTOR signaling pathway, and apoptosis, et al. Among those differentially expressed LncRNAs, nine key LncRNAs were selected (MALAT1, NUTM2A-AS1, and LINC00963 had high expression; LINC00622, MAPKAPK5-AS1, LINC02289, XPC-AS1, ZFAS1 and SNHG5 had low expression) by qPCR. This study suggests that different expressions of LncRNAs may involve in the potential function in leishmaniasis and provide a novel insight for diagnosis of this zoonotic disease.

Exploring the role of secretory proteins in the human infectious diseases diagnosis and therapeutics

Secretory proteins are playing important role during the host-pathogen interaction to develop the infection or protection into the cell. Pathogens developing infectious disease to human being are taken up by host macrophages or number of immune cells, play an important role in physiological, developmental and immunological function. At the same time, infectious agents are also secreting various proteins to neutralize the resistance caused by host cells and also helping the pathogens to develop the infection. Secretory proteins (secretome) are only developed at the time of host-pathogen interaction, therefore they become very important to develop the targeted and potential therapeutic strategies. Pathogen specific secretory proteins released during interaction with host cell provide opportunity to develop point of care and rapid diagnostic kits. Proteins secreted by pathogens at the time of interaction with host cell have also been found as immunogenic in nature and numbers of vaccines have been developed to control the spread of human infectious diseases. This chapter highlights the importance of secretory proteins in the development of diagnostic and therapeutic strategies to fight against human infectious diseases.

Compliance of Primary Healthcare Workers in Saudi Arabia With the National Surveillance System of Tropical and Non-tropical Dermatological Diseases

BACKGROUND

 Control and prevention of infectious diseases has been a primary health mandate. The reporting system is a vital step in preventing and controlling of these diseases. Most important, healthcare workers who have a responsibility to report must be aware of this responsibility. The present study aimed to improve the compliance of primary healthcare workers against reportable tropical and non-tropical dermatological diseases.

OBJECTIVE OF THE STUDY

The objective was to assess the knowledge, skills, and practice of primary healthcare workers in Saudi Arabia regarding the surveillance system of reportable tropical and non-tropical dermatological diseases using an assessment tool featuring closed-ended questions. As a secondary objective, this study assessed the satisfaction of primary healthcare workers with the surveillance system.

SUBJECTS AND METHODS

 Through a cross-sectional design, the study used an electronic self-administered questionnaire targeting the primary healthcare workers who met the inclusion criteria through a non-probability sampling technique.

RESULTS

By the end of the study period, data had been collected from 377 primary healthcare workers. Slightly more than half of them worked for the ministry of health facilities. In the last year, the vast majority (88%) of participants did not report any infectious diseases. Poor or low knowledge was reported by almost half of the participants concerning which dermatological diseases should be notified immediately on clinical suspicion or routinely on a weekly basis. Clinically and in response to the skills assessment, 57% of the participants had lower skills scores in detecting and identifying the skin ulcer of leishmania. Half of the participants were less satisfied with the feedback after their notification and considered the notification forms complicated and time-consuming, especially with the usual high workload in primary healthcare centers. Furthermore, the observed significant differences (p < 0.001) in knowledge and skill scores were demonstrated with female healthcare workers, older participants, employees from the Ministry of National Guard Health Affairs, and workers with more than ten years of experience.

CONCLUSION

The present study has shown the limitations of public health surveillance due to underreporting and lack of timeliness. The dissatisfaction of study participants with feedback after the notification step is another finding that demonstrates the need for collaboration among public health authorities and healthcare workers. Fortunately, health departments can implement measures to improve practitioners' awareness through continuous medical education and providing frequent feedback to overcome these hurdles.

Omics Approaches in Drug Development against Leishmaniasis: Current Scenario and Future Prospects

Leishmaniasis is a zoonotic disease transmitted in humans by the bite of Leishmania-infected phlebotomine sandflies. Each year approximately 58,500 cases of leishmaniasis are diagnosed across the globe, with a mortality rate of nearly seven percent. There are over 20 parasitic strains of Leishmania which are known to cause distinct types of leishmaniasis and pose an endemic threat to humans worldwide. Therefore, it is crucial to develop potential medications and vaccines to combat leishmaniasis. However, the task of developing therapeutic solutions is challenging due to Leishmania's digenetic lifecycle. The challenge is further intensified by cases of resistance against the available drugs. Owing to these challenges, the conventional drug development regimen is further limited by target discovery and ligand suitability for the targets. On the other hand, as an added advantage, the emergence of omics-based tools, such as high-end proteomics, transcriptomics and genomics, has hastened the pace of target discovery and target-based drug development. It is now becoming apparent that multi-omics convergence and an inter-connected systems approach is less time-consuming and more cost-effective for any drug-development process. This comprehensive review is an attempt to summarize the current knowledge on the muti-omics approach in drug development against leishmaniasis. In particular, it elaborates the potential target identification from secreted proteins in various stages of Leishmania infection and also illustrates the convergence of transcriptomic and genomic data towards the collective goal of drug discovery. This review also provides an understanding of the potential parasite's drug targets and drug resistance characteristics of the parasite, which can be used in designing effective and specific therapeutics.

Review of the Clinical Presentation, Pathology, Diagnosis, and Treatment of Leishmaniasis

Leishmaniasis is a vector-borne infection caused by kinetoplastid protozoans in the genera Leishmania and Endotrypanum. The disease occurs worldwide in the tropics and subtropics and can be particularly burdensome in resource-limited settings. Diseases caused by leishmaniasis range in severity from mild cutaneous lesions to life-threatening visceral and disfiguring mucocutaneous illnesses. Rapid and accurate diagnosis is needed to ensure proper clinical management of patients afflicted with this disease. Complicating matters of diagnosis and treatment are the diversity of species within these 2 genera and the variable specificity of diagnostic assays. This mini-review provides laboratory professionals with an overview of Leishmania epidemiology, biology, pathogenesis, clinical presentations, and treatments with additional emphasis placed on the nuances involved in diagnosis.

Chemical Composition and In Vitro and In Silico Antileishmanial Evaluation of the Essential Oil from Croton linearis Jacq. Stems

Croton linearis Jacq. is an aromatic shrub that has been utilized in traditional medicine in the Bahamas, Jamaica, and Cuba. Recent studies have revealed the antiprotozoal potential of its leaves. The present work is aimed to identify the volatile constituents of essential oil from the stems of C. linearis (CLS-EO) and evaluate its in vitro antileishmanial activity. In addition, an in silico study of the molecular interactions was performed using molecular docking. A gas chromatographic-mass spectrometric analysis of CLS-EO identified 1,8-cineole (27.8%), α-pinene (11.1%), cis-sabinene (8.1%), p-cymene (5.7%), α-terpineol (4.4%), epi-γ-eudesmol (4.2%), linalool (3.9%), and terpinen-4-ol (2.6%) as major constituents. The evaluation of antileishmanial activity showed that CLS-EO has good activity on both parasite forms (IC_{50Promastigote} = 21.4 ± 0.1 μg/mL; IC_50Amastigote = 18.9 ± 0.3 μg/mL), with a CC₅₀ of 49.0 ± 5.0 μg/mL on peritoneal macrophages from BALB/c mice (selectivity index = 2 and 3 using the promastigote and amastigote results). Molecular docking showed good binding of epi-γ-eudesmol with different target enzymes of Leishmania. This study is the first report of the chemical composition and anti-Leishmania evaluation of CLS-EO. These findings provide support for further studies of the antileishmanial effect of this product.

Monitoring Leishmania infantum Infections in Female Lutzomyia longipalpis by Using DNA Extraction on Cation Exchange Paper and PCR Pool Testing

Visceral leishmaniasis remains a serious public health issue, and Brazil was among the seven countries with the highest prevalence of this disease worldwide. The measures to control this disease are not easily developed, and the improvement of its diagnosis, surveillance, and control is still needed. This study aimed to carry out the polymerase chain reaction (PCR) diagnosis of Leishmania infantum in vector samples in some municipalities of the State of São Paulo, which included two municipalities with human disease transmission and two with dog transmission only. Vectors were collected in traps with luminous bait. Next, they were killed at -4 °C and kept in 70% alcohol. Groups of ten female insects (pools) were mashed on cation exchange paper (fine cellulose phosphate with 18 µEq/cm² ionic exchange capacity) for DNA extraction. The PCR was carried out to identify the natural infection of the Leishmania genus in female Lutzomyia longipalpis (Lu. Longipalpis). Out of the 3,880 Lu. longipalpis phlebotomines, 1060 were female and 2820 were male (3:1). The method used to extract the DNA in pools of ten phlebotomines and the PCR resulted in sensitivity, specificity, practicality, and faster analyses when compared to the individual analysis method. The procedure described can be used on a large scale in the leishmaniasis epidemiological surveillance, enabling a higher number of analyses and the optimization of human resources because the traditional diagnostic method is carried out via desiccation of the insect digestive system and microscopic examination, which is time-demanding and there is the need of manual skills.

An Overview on Leishmaniasis in Romania: Diagnosis and Therapeutics

Leishmaniasis, a vector-borne disease considered to be one of the twenty neglected diseases by the World Health Organization, represents one of the public health concerns in endemic countries. In humans, as well as in animal counterparts, the infection can evolve with different clinical localizations, such as those that are cutaneous, mucocutaneous and visceral. Romania has been traditionally considered a nonendemic country for Leishmania species infection and has had sporadic positive human cases; however, the climate change recorded in recent decades has created potentially optimal conditions for the preponderant vectors of Phlebotomus spp., which has lately been identified in various parts of country. Moreover, with people and dogs (the prevailing hosts) traveling in endemic countries, the disease was imported and diagnosed in both species, and became a medical concern. In this review, we focused on the: (1) epidemiological data of leishmaniasis cases, both in humans and animals, reported by Romania; (2) diagnostic tools available for confirmation since there is a lack of gold-standard laboratory methods for human and dog patients; and (3) conventional antileishmanial therapy.

Cutaneous/Mucocutaneous Leishmaniasis Treatment for Wound Healing: Classical versus New Treatment Approaches

Cutaneous leishmaniasis (CL) and mucocutaneous leishmaniasis (ML) show clinical spectra that can range from a localized lesion (with a spontaneous healing process) to cases that progress to a generalized systemic disease with a risk of death. The treatment of leishmaniasis is complex since most of the available drugs show high toxicity. The development of an effective topical drug formulation for CL and ML treatment offers advantages as it will improve patient’s compliance to the therapy given the possibility for self-administration, as well as overcoming the first pass metabolism and the high costs of currently available alternatives. The most common dosage forms include solid formulations, such as membranes and semi-solid formulations (e.g., ointments, creams, gels, and pastes). Topical treatment has been used as a new route of administration for conventional drugs against leishmaniasis and its combinations, as well as to exploit new substances. In this review, we discuss the advantages and limitations of using topical drug delivery for the treatment of these two forms of leishmaniasis and the relevance of combining this approach with other pharmaceutical dosage forms. Emphasis will also be given to the use of nanomaterials for site-specific delivery.

Biophysical and ultrasonographic changes of acute Old World cutaneous leishmaniasis skin lesions in comparison with uninvolved skin: A possible tool for non-invasive early detection and treatment outcome assessment

BACKGROUND

Cutaneous leishmaniasis (CL) is a skin disease caused by intracellular protozoa, which is endemic in Iran. The goal of this study was to compare biophysical characteristics in CL lesions with uninvolved skin.

METHODS

Stratum corneum hydration, transepidermal water loss, surface friction, pH, sebum, melanin, erythema, temperature, elasticity parameters (R0, R2, and R5), thickness and echo-density of epidermis and dermis were measured on the active erythematous indurated part of a typical CL lesion in 20 patients, and compared with the same location on the other side of the body as control. Paired t- test was used for statistical analyses and a P<0.05 was considered significant.

RESULTS

Melanin content, R2 and echo-density of dermis were significantly lower, whereas transepidermal water loss, friction index, pH, erythema index, temperature and the thickness of dermis were significantly higher in CL lesions. There was no significant difference in stratum corneum hydration, sebum, R0, R5, thickness of epidermis and density of epidermis between CL and normal skin.

CONCLUSIONS

CL lesions are characterized by certain changes in biophysical and ultrasonographic properties, which are mostly correlated with histological features. These changes are likely to be useful in the non-invasive early detection of CL and also as treatment outcome measures for clinical trials of new treatment modalities for CL in the future. This article is protected by copyright. All rights reserved.

Nanomedicine in leishmaniasis: A promising tool for diagnosis, treatment and prevention of disease - An update overview

Leishmaniasis is a neglected tropical disease that has a wide spectrum of clinical manifestations, ranging from visceral to cutaneous, with millions of new cases and thousands of deaths notified every year. The severity of the disease and its various clinical forms are determined by the species of the causative agent, Leishmania, as well as the host's immune response. Major challenges still exist in the diagnosis and treatment of leishmaniasis, and there is no vaccine available to prevent this disease in humans. Nanotechnology has emerged as a promising tool in a variety of fields. In this review, we highlight the main and most recent advances in nanomedicine to improve the diagnosis and treatment, as well as for the development of vaccines, for leishmaniasis. Nanomaterials are nanometric in size and can be produced by a variety of materials, including lipids, polymers, ceramics, and metals, with varying structures and morphologies. Nanotechnology can be used as biosensors to detect antibodies or antigens, thus improving the sensitivity and specificity of such immunological and molecular diagnostic tests. While in treatment, nanomaterials can act as drug carriers or, be used directly, to reduce any toxic effects of drug compounds to the host and to be more selective towards the parasite. Furthermore, preclinical studies show that different nanomaterials can carry different Leishmania antigens, or even act as adjuvants to improve a Th1 immune response in an attempt to produce an effective vaccine.