2025/07/17 by Aboagye, Yussif Owusu, Arndts, Kathrin, Ritter, Manuel +2
#Life Sciences #Medicine and Health Sciences
paper · doi:10.17605/osf.io/k3bmg
1. Description Leishmaniasis is a neglected tropical disease caused by protozoan parasites of the *Leishmania* genus and transmitted through female phlebotomine sandflies. The disease presents in multiple clinical forms—cutaneous, visceral, mucocutaneous, and post-kala-azar dermal leishmaniasis (PKDL)—each with distinct public health challenges. Globally, over one billion people are at risk, and millions are infected, particularly in low-income regions of Africa, Asia, South America, and the Middle East. Despite the disease's burden, global control efforts are hindered by fragmented knowledge, delayed diagnosis, limited therapeutic options, and insufficient integration into national health policies. While many studies have explored the epidemiological, diagnostic, and therapeutic dimensions of leishmaniasis, there remains a lack of consolidated evidence that can inform integrated and context-specific interventions. This scoping review will aim to synthesize current global evidence on the diagnosis, treatment, and clinical burden of leishmaniasis, identify research gaps, and inform public health interventions and policymaking. The review will be conducted in accordance with the PRISMA Extension for Scoping Reviews (PRISMA-ScR) guidelines. 2. Objectives The review will address the following five key objectives: 1. Epidemiology: To examine the global and regional distribution patterns of the major forms of leishmaniasis (cutaneous, visceral, mucosal, mucocutaneous, and PKDL), highlighting endemic regions, transmission patterns, and burden trends. 2. Diagnostic Strategies: To map diagnostic approaches across clinical forms of leishmaniasis, including molecular techniques, rapid diagnostic tests, serological assays, and microscopy, and assess their reported sensitivity, specificity, and field applicability. 3. Treatment Modalities and Outcomes: To review current treatment regimens by disease type and region, including monotherapies and combination therapies, and evaluate clinical outcomes, relapse rates, resistance, and adverse effects. *Policy and Practice Gaps: To identify implementation barriers, regional inequalities in care access, and areas where diagnostic or therapeutic tools are underutilized or ineffective. *Research Gaps and Recommendations: To highlight under-researched populations, geographic regions, and clinical aspects, and propose areas for future investigation to support more targeted disease control strategies. 3. Methodology This review will use the Arksey and O’Malley framework for scoping reviews, refined by Levac et al., and reported in line with PRISMA-ScR guidelines. The five-step approach will include: 1. Identifying the research questions 2. Identifying relevant studies 3. Selecting eligible studies 4. Charting the data 5. Collating, summarizing, and reporting the results The scoping review will include descriptive analysis and thematic synthesis to explore patterns and identify knowledge gaps. 4. Eligibility Criteria Inclusion Criteria * Studies published from January 2000 to April 2025 * Studies involving human subjects diagnosed with any form of leishmaniasis * Primary research studies including quantitative, qualitative, and mixed-methods studies * Research addressing epidemiological trends, diagnostic methods, or treatment outcomes * Studies conducted in either endemic or non-endemic regions * Articles written in English Exclusion Criteria * Non-English publications * Animal-only or in-vitro laboratory studies without clinical or epidemiological relevance * Review articles, editorials, expert opinions, or conference abstracts without accessible full text * Case reports or case series with fewer than five patients * Studies focusing solely on sandfly vector biology or ecology without patient-based outcomes 5. Information Sources and Search Strategy A comprehensive search will be conducted in the following electronic databases: * PubMed * Scopus * ScienceDirect Search strategies will combine Medical Subject Headings (MeSH) and free-text keywords related to: Leishmaniasis, visceral leishmaniasis, cutaneous leishmaniasis, mucocutaneous leishmaniasis, diagnosis, treatment, clinical outcome, relapse, drug resistance, and burden. Boolean operators such as AND, OR, and truncations (e.g., "leishmaniasis") will be used to maximize retrieval. Searches will be tailored to each database and documented for transparency. Backward and forward citation tracking will be performed on included studies and key reviews to identify additional relevant literature. A manual search of WHO and relevant NTD-related publications will supplement database results. 6. Study Selection Process All retrieved citations will be imported into Zotero for duplicate removal. Title and abstract screening will be carried out independently by two reviewers. Full-text review of eligible studies will follow using a structured eligibility checklist. Discrepancies will be resolved through consensus or arbitration by a third reviewer. The study selection process will be documented using a PRISMA-ScR flow diagram, reporting the number of records identified, screened, excluded, and included. 7. Data Extraction and Charting A standardized data extraction form will be developed and piloted in Microsoft Excel. The following information will be extracted: * Study title and authors * Year of publication * Country/region of study * Study design and duration * Type and form of leishmaniasis * Population characteristics (age, sex, comorbidities) * Diagnostic methods used, with reported accuracy (sensitivity/specificity) * Treatment regimens and reported clinical outcomes * Relapse rates, adverse effects, and resistance (if applicable) * Key findings, limitations, and author recommendations Two reviewers will independently extract data. Extracted data will be cross-checked, and discrepancies will be resolved through discussion. 8. Data Synthesis and Analysis Data will be synthesized narratively and organized around the three core domains: epidemiology, diagnostics, and treatment outcomes. Descriptive statistics (frequencies, proportions) will be calculated to show trends in disease burden, diagnostic performance, and treatment effectiveness across regions and disease types. Findings will be presented in tables, figures, and thematic maps, where applicable. A matrix will be developed to summarize gaps in diagnostics, treatment accessibility, and regional disparities. 9. Quality Assessment As per scoping review methodology, no formal risk of bias assessment will be performed. However, the clarity of methods, relevance to objectives, and sample size will be considered during interpretation of findings. Studies with insufficient methodological detail will be noted but not excluded if they offer contextually important information.