Leishmaniases in Ethiopia: a scoping review protocol to determine the scope of research and remaining gaps

STRENGTHS AND LIMITATIONS OF THIS STUDY

  • This study uses a comprehensive codebook that has been previously published and since refined, thereby ensuring that the analysis of the body of literature is complete.

  • All manuscripts in English language published in peer-reviewed journals will be considered. While some publications in non-peer-reviewed journals may be missed, publications in other languages are thought to be rare.

  • The inclusion criteria require an in-depth discussion of the leishmaniases in Ethiopia, and ultimately, the concept of ‘in-depth discussion’ is subjective, though this will be mitigated by a dual and independent review process.

Introduction

Background

Leishmaniases are vectorborne protozoan diseases recognised in the group of the neglected tropical diseases (NTDs). They are endemic in 99 countries with 4 clinical manifestations namely, visceral (VL), cutaneous (CL; diffuse and localised), mucocutaneous and post kala-azar dermal.1 2 Over 200 000 cases of CL and 12 000 cases of VL were reported to the WHO in 2022. The African region reports 4% and 33% of the global CL and VL cases, respectively.1

Ethiopia is considered an important contributor to the East African VL hotspot with 2500–4000 VL cases and 20 000–30 000 cases of CL occurring annually.3 Leishmania donovani is responsible for VL in Ethiopia while Leishmania aethiopica, Leishmania major and Leishmania tropica are the main parasites responsible for CL.4 5 Both VL and CL are spread by several Phlebotomus vectors, including Phlebotomus orientalis, Phlebotomus celiae and Phlebotomus martini.4 5 While CL is endemic in most highlands in Ethiopia, VL is common in the lowland areas in Northwest and Southwest bordering Sudan, South Sudan and Kenya.6 While poverty and low educational level are a general risk factor for both VL and CL, VL predominantly affects young migrant men farm workers.7 Sleeping under Balanite or Acacia trees and the presence of termite hills in the surrounding area indicate risk for VL while the presence of hyraxes, animal ownership and cracked house walls are risk factors for both CL and VL.7–10 Transmission is catalysed by regional conflicts, deforestation and migration, with several outbreaks occurring in recent years including a CL outbreak in the Somali region in mid to late 2023, which required WHO intervention.11 12

Elimination of VL as a public health problem (EPHP) has been declared in the 2030 WHO framework Ending the neglect to attain the Sustainable Development Goals: A roadmap for neglected tropical diseases 2021–2030.13 14 Given successful interventions to near elimination in Southeast Asia and the high burden of the disease in Eastern Africa, attention has turned towards VL EPHP in East Africa with calls to action emphasising investment and collaboration.15 16 Leishmaniasis is included in the Ethiopian Ministry of Health’s (MOH) Third National Neglected Tropical Disease Strategic Plan for 2021–2025, with the goal to reduce VL case fatality to less than 1%, increase treatment centres by 2030, and ultimately eliminate the disease as a public health problem. In contrast, the MOH’s goal for CL is to control by 2030 by detecting and reporting 85% of cases and treating 95%, as well as increasing treatment and diagnostic centres.3

For effective programme implementation, reviewing available evidence and setting research priorities remains important. The scoping review set forth by this protocol aims to identify the scope of research on the leishmaniases in Ethiopia and identify what gaps remain. This follows a similar scoping review on the leishmaniases in Kenya completed by this team in 2023.2

Rationale

Ethiopia has shown commitment to eliminate VL as part of the Nairobi Declaration. The WHO regional technical Meeting of Stakeholders on Elimination of Visceral Leishmaniasis in East Africa held in Nairobi on 24 January 2023–27 January 2023 discussed the need for understanding the research landscape.13 Understanding the status of research on the leishmaniases in Ethiopia will help delineate present and next plans for VL elimination and CL control. The scoping review will help identify which areas of research are well investigated. In addition, it will bring to attention areas that need further research and help stakeholders set research priorities. It also invites the potential to conduct systematic reviews into more specific questions. With the MOH’s focus on NTDs, we see a priority to focus on the landscape of leishmaniases research to identify what research gaps remain. We have not identified an existing scoping review of the leishmaniases in Ethiopia focusing on the whole body of literature. Our team has conducted a scoping review on leishmaniases Kenya2 which was the first in what we anticipate will be a series to include other countries in the region.

Objective

The study objective is to examine the body of peer-reviewed literature and governmental or non-governmental international regulatory body publications on leishmaniasis in Ethiopia, define the scope of research and determine what gaps remain. This will be completed through a multiphase screening and data extraction process. The study aims to answer one primary question and several secondary questions.

  1. What are the main types of research that have been conducted on leishmaniasis in Ethiopia and what research gaps remain?

    1. What aspects of leishmaniasis were predominantly investigated?

    2. During what period was most of the research conducted?

    3. What gaps remain in the scope of research?

    4. What organisations fund leishmaniasis research in Ethiopia?

    5. What journals publish research on leishmaniasis in Ethiopia?

    6. What are the most influential papers, assessed through citation index, on leishmaniasis in Ethiopia?

Methods

This protocol was developed with reference to the JBI Scoping Review Methodology Group’s guidance on conducting scoping reviews and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses- Extension for Scoping Reviews (PRISMA-ScR) reporting guidelines.17–19 (online supplemental appendix 1). We anticipate data collection will be completed by 31 July 2024, and that data extraction and analysis will begin in August 2024.

Supplemental material

Inclusion and exclusion criteria

Inclusion criteria:

  1. Primary criteria

    1. Articles in English.

  2. Secondary criteria

    1. Articles focusing on leishmaniasis or kala-azar.

      1. Expanded during the title-abstract screen to include broader categories that leishmaniasis could be included in (eg, NTDs, vectorborne diseases, leishmania).

    2. Articles focusing on Ethiopia

      1. Expanded during the title-abstract screen to include broader categories that Ethiopia could be included in (eg, East Africa, sub-Saharan Africa).

Exclusion criteria

  1. Articles with a focus on Ethiopia that do not contain an in-depth discussion of leishmaniasis with an in-depth discussion being defined as describing one or more aspects of the identified themes for the review.

  2. Articles with a focus on leishmaniasis that do not contain an in-depth discussion of Ethiopia with an in-depth discussion being defined as the study taking place in Ethiopia or, if secondary research, having included studies that took place in Ethiopia.

  3. Texts not published in peer-reviewed journals or by government or international regulatory bodies.

  4. Texts published as conference proceedings, poster abstracts or book chapters.

  5. Articles where the full text could not be accessed or located.

Search strategy

Articles will be gathered through searches of PubMed, Embase via Embase.com, Web of Science Core Collection, Cochrane Library, Global Index Medicus, ClinicalTrials.gov, the Pan African Clinical Trials Registry and PROSPERO. There will be no publication date restrictions. Locally published literature that may not be indexed in the databases being searched will be identified through team members (ED, EA and MSA) familiar with the setting. The search terms used for each database can be found in online supplemental appendix 2.

Supplemental material

Record management

Deduplication of abstracts using the De-duplicator from Bond University’s Systematic Review Accelerator will be used.20 Records will be screened using Rayyan, an article screening tool for evidence synthesis projects.21

Screening strategy

The screening process will have two phases. The first phase will be the title-abstract screen, where the primary inclusion criteria must be met and at least one of the secondary inclusion criteria must be met. This broader criterion is to ensure that no articles are excluded because they do not explicitly or exclusively discuss leishmaniasis in Ethiopia in the title or abstract. The second phase will be the full-text screen, where all inclusion criteria must be met for the text to be included in the analysis.

In both phases, two reviewers will independently and blindly screen each record for inclusion or exclusion (KO and all students in the acknowledgements). Conflicts will be resolved by a third reviewer (KO and GG). Prior to beginning, a test batch of articles will be used to train reviewers.

Data extraction

Data extracted from the included texts will follow a codebook which defines texts by study themes, types and study design. Themes describe the text’s focus in the context of leishmaniasis (eg, pathophysiology, diagnostics, vectors). Study type describes the text’s focus in terms of specific methodology with categories (eg, clinical research, epidemiological research) and subcategories (eg, diagnostic development, molecular epidemiology). Study design describes general research processes (eg, randomised controlled trial, cohort study). These are outlined in online supplemental appendix 3. This codebook was adapted from the previous scoping review performed by this group.2 Small modifications were made after advice from Ethiopian collaborators (EA, MSA and ED) most notably the inclusion of study design as a standalone categorisation where it was previously included under the type of study. Microsoft Excel will be used for data extraction, analysis and summarisation. Any adaptations to the codebook during the review process will be highlighted in the final manuscript.

Supplemental material

Data summarisation and presentation

Summary statistics will be used to describe the spread of literature across study themes, study design and types. In addition, summary statistics of the year of publication, the number of citations (via Google Scholar citations), publishing bodies and funding sources will be described. This will help to understand well-researched aspects of leishmaniasis in the country and areas needing more attention for the future.

Ethics and dissemination

We plan to disseminate our findings to the appropriate stakeholders both in Ethiopia and globally through publication in peer-reviewed open-access journals, conference presentations and sharing publications with relevant stakeholders. This review is based on published manuscripts. Individual consenting and ethical approvals are not applicable. The study was also registered in the Center for Open Science’s OSF registries where any amendments to the protocol will be available.

Patient and public involvement

There is no applicable patient and public involvement in the study.

Discussion

The goal of this scoping review is to capture all literature relating to the leishmaniases in Ethiopia, to describe the research landscape and to identify research gaps to inform future research priorities. To this end, our methodology possesses several strengths and limitations. Our greatest strength is that we will undertake a comprehensive search strategy, crafted with input from a multidisciplinary team from Ethiopia and the USA, using broad search terms to capture the most expansive set of results possible relating to Ethiopia and leishmaniasis. This will allow us to accurately assess the research landscape and identify gaps. In addition, the use of dual and independent reviews of both abstracts and full texts in our approach will allow us to minimise bias while ensuring abstracts and articles are assessed correctly. We also believe that the comprehensive codebook, designed with input specifically on the Ethiopian context, will help accurately examine the scope of research. Finally, all articles published in the English language will be considered, and given that the medical and educational language in Ethiopia is English, we are confident we will gather the full body of relevant literature. Publications in local languages are often for community awareness and not scientific research, thus, will not impact the review.

While our methodology is strong, it is not without its limitations. Ultimately, some studies may be missed from inclusion if they are unable to be located, also leading to the exclusion of possibly relevant publications. There may be relevant articles in local journals or non peer-reviewed journals, which will be excluded. However, excluding articles in non-peer-reviewed journals helps uphold the overall quality of the gathered body of literature. In addition, if articles do not specify a form of leishmaniasis, the Leishmania species will be used as a proxy given clinical association with certain species. We acknowledge that this research is still evolving, and future studies may reveal new links between Leishmania species and clinical association. Lastly, we will not be performing any quality assessment on the included studies as that is not within the scope of a scoping review. However, given that all or most included articles will have been peer-reviewed, this indicates quality to an extent.

Our analysis will provide key insights into the landscape, timeline and robustness of leishmaniasis research in Ethiopia, which we hope will be used by the academic community to inform future work and by the MOH and other partners to evaluate progress and shape programmes. With the Ethiopian MOH actively working on NTD elimination and control, we believe that our scoping review will catalyse future research on leishmaniasis.

Ethics statements

Patient consent for publication

Acknowledgments

The authors would like to acknowledge the students who will assist with the abstract and full-text screens: Abigail Binkley, Benjamin Boutselis, Amer Chaudhry, Riley Fanning-Hughes, Khushi Gandhi, Mahlet Haile, Ellie Krulwich, Laith Matari, Shreyas Mosurkal, Leah Oruko, Isabel Roman, Prapti Shah, Sara Shaikh, Adriana Totten, and Abigail Williams.

References

  1. The third national neglected tropical diseases strategic plan 2021-2025. Addis Ababa Ministry of Health; 2021.

  2. Ending the neglect to attain the sustainable development goals: a road map for the neglected tropical diseases 2021-2030. Geneva World Health Organization; 2021.

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