Background and rationale

Neglected tropical diseases (NTDs) are a group of diseases and conditions that prevail in tropical and subtropical areas mainly in low- and middle-income countries, where inadequate sanitation and poor health services are common [1]. NTDs can cause illness, physical and mental suffering, disability, and stigma, decrease productivity and negatively affect children’s education [2]. Several clinical manifestations are associated with NTDs. For example, lymphatic filariasis (LF) may cause elephantiasis and hydrocele which are highly disfiguring and painful conditions for those affected [3]. Leprosy and leishmaniasis cause disfiguring, and stigmatizing scars and can lead to mental distress in affected patients [4] while urogenital schistosomiasis causes male and female genital lesions causing immeasurable suffering and shame, especially in Africa [5,6]. Other NTDs, such as onchocerciasis, can remain asymptomatic for years before complications emerge, resulting in a delayed diagnosis and more severe outcomes like river blindness [2].

The five most prevalent NTDs worldwide include: LF, onchocerciasis, schistosomiasis, soil-transmitted helminths (ascariasis, trichuriasis, and hookworm infection) and trachoma. These diseases can be controlled by preventive chemotherapy (PC-NTDs) delivered through mass drug administration (MDA) [7]. MDA is a safe and inexpensive means of delivery of essential drugs based on the principles of preventive chemotherapy, where populations or sub-populations are offered treatment regardless of their disease status [8]. These recommendations are based on the epidemiology of NTDs, host-parasite interaction, patient acceptability and drug effect [9,10].

Significant progress has been made in reducing the transmission and burden of NTDs worldwide through PC-NTDs [11,12]. In Africa, MDA and other control efforts have recently led to certification of national elimination of LF in Malawi [13] and Togo [14] bringing the total number of countries globally with LF elimination status to nineteen (19) [15]. In Mali, trachoma was eliminated in 2023 [16] and for onchocerciasis, Mali was successful at the pre-stop MDA survey in 2019 [17]. The pre-stop MDA survey assesses key epidemiological and entomological indicators to determine if treatment can be safely stopped without risking disease resurgence.

Despite these achievements, there remain many population groups or geographic areas that have not been reached with MDA interventions [18,19]. Not only does this contribute to inequity for those left untreated, but it also compromises the achievement of NTD elimination. Elimination goals remain in danger if at-risk groups like mobile and migrant populations (MMPs) (including nomadic pastoralist communities, internally displaced persons (IDPs)) routinely miss MDA, potentially contributing to hotspots that could lead to disease re-emergence [20]

The control and elimination of NTDs requires the treatment of all eligible individuals in all population groups, following the principle that no one should be left behind. Over the past decade, the risks and vulnerabilities faced by migrant and mobile populations in Africa have been compounded. For example, in the Sahel region, armed conflict, terrorism, poverty, violence, and growing insecurity have all contributed to an increased influx of people on the move [21]. MMPs are a significant proportion of the population in the African region [22,23]. Insecurity and exacerbated poverty are responsible for mobility that involves IDPs, nomadic pastoralists, refugees, migrants, among others. These individuals have been shown to have the least access to MDA when compared to the general population [24]. Climate change and severe weather events such as droughts, floods, and extreme heat are driving increased mobility as communities are forced to migrate/move in search of water, arable land, and livelihood opportunities. These movements often heighten vulnerabilities by disrupting access to essential health services particularly through interruptions in continuity of care. These movements also create health challenges in both the home and host communities that people leave and those they move to as mobile populations may miss essential preventative health measures, such as immunizations or antenatal care, due to constant movement in the home and host districts. In the host district, an influx of people can overwhelm local health facilities, resulting in longer wait times, shortages of medical supplies, and pressure on healthcare personnel [25].

Today, little is known about how best to provide essential health care to mobile and migrant populations. The constant mobility of populations marginalizes them or even excludes them from health services. To address this issue among mobile populations living in vulnerable circumstances, it is essential to understand the context in which interventions can be effective in responding to these specific situations. What are the barriers and facilitators to accessing MDA for PC-NTDs among MMPs (nomadic pastoralists, migrant laborers, IDPs, and refugees) in Africa; Why are these populations moving? Where are these populations coming from or going to? What challenges are associated with the capacity and willingness of stakeholders, including the beneficiary populations, to successfully implement MDA in order to effectively control/eliminate NTDs and other infectious diseases?

Objectives

To address these questions, we will conduct a scoping review to explore the influence of population mobility on the implementation of mass drug administration (MDA) for preventive chemotherapy neglected tropical diseases (PC-NTDs) in Africa. This review aims to explore the factors driving population movement and assess their consequences on health outcomes, particularly in relation to the implementation and effectiveness of MDA programs in Africa. We seek to explore three primary questions:

1. Reasons for movement and patterns: to understand the key factors driving the movement patterns of MMPs in sub-Saharan Africa that impact the implementation of MDA for PC-NTDs, including seasonal work, conflict, insecurity, and nomadic lifestyles.
2. Consequences on MDA programs: To determine the health-related impacts of these movements on MDA programs, including how mobile populations might miss treatments, the challenge of re-administering drugs, potential increased transmission of diseases, and the strain on health systems in Africa.
3. Successful approaches documented: to compile evidence of successful approaches shown to effectively improve MDA coverage among mobile populations in sub-Saharan Africa, with a focus on impact and outcome data.

Expected anticipated results

Protocol design

We will use the Joanna Briggs Institute methodology (JBI) guidance for scoping reviews to conduct the study [31] and the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) [32] for writing the protocol (S1 File). The review protocol will not be registered within the International Prospective Register of Systematic Reviews (PROSPERO) because scoping reviews are not currently accepted. We will utilize the PRISMA extension for scoping reviews (PRISMA-ScR) as the reporting guidelines for the scoping review manuscript [33].

Eligibility criteria

Methodological framework for conducting the scoping study: In this paper we will use PCC (Population (or participants)/concept/context) framework to guide the research question and inform the search strategy for our scoping review [34].

Population: Our population will include mobile populations, such as those defined above, in regions where MDA for PC-NTDs is being implemented. We will include basic characteristics of participants, such as age, gender, education, economic status.

Concept/Intervention: The concept we will be examining in this scoping review is the implementation of MDA for preventive chemotherapy NTDs (PC-NTDs). Health outcomes will include MDA coverage rates, treatment adherence, disease transmission rates, and progress toward NTD elimination. Impact outcomes will include the overall success, easured by coverage rate, of MDA programs, and challenges, such as delays or setbacks in disease control due to missed treatments and reinfection risks.

Context: In Sub-Saharan Africa, population mobility severely hampers public health interventions, particularly MDA programs targeting NTDs including lymphatic filariasis, onchocerciasis, trachoma, schistosomiasis, and soil-transmitted helminths [35].

To accomplish the goal of disease elimination, these programs mostly depend on high levels of drug coverage throughout populations [36]. However, in regions where communities are highly mobile due to nomadic lifestyles, seasonal migration, labor migration, or displacement due to conflict or climate change, MDA coverage can be severely impacted [24,37,38]. Geographically, many of these areas in Africa are characterized by remote, hard to reach, rural locations with inadequate health infrastructure and limited access to health care. Efforts to ensure continuity of care along with consistent use of drugs are complicated by the temporary and unpredictable nature of mobile populations, which frequently cross borders internationally [39]. Culturally, some of these populations may have beliefs that can influence their willingness to participate in MDA campaigns. Factors such as language barriers, trust in health systems, and knowledge about NTDs may further exacerbate the challenge. Additionally, this scoping review may also examine how certain sub-groups within these mobile populations such as women, children, or ethnic minorities are differently affected by MDA campaigns [40].

Inclusion/Exclusion criteria

We will include studies conducted from 2000 until 2024 because, since the 2000s, global efforts to eliminate NTDs such as lymphatic filariasis and onchocerciasis have intensified. International initiatives such as the Global Program for the Elimination of Lymphatic Filariasis (GPELF), launched by WHO in 2000, have marked a turning point in strategies to combat these diseases [41]. The collection of more accurate data on MDA campaigns and population movements has also been enhanced using technological advances, such as Geographic Information Systems (GIS) and health surveillance tools (molecular xenomonitoring) [42,43]. Cross-border migration, humanitarian crises, and refugee and internally displaced person flows have increased, especially after 2000 because of wars in the Middle East and Africa [38].

This study will involve all study designs including randomized controlled trials, non-randomized controlled studies, quasi-experimental, observational studies, and evaluation studies of MDA. Studies published in peer-review journals and found in grey literature will be included. The references cited in the reviewed literature will be searched to identify additional relevant studies. Only studies focusing on Africa will be included. We will include only papers and documents published in English and French.

We will exclude studies that (1) are conducted outside Africa, (2) are prior to the year 2000, (3) are not in French or English, (4) focus on topics unrelated to MDA campaigns, preventive chemotherapy NTD elimination efforts or mobile populations as defined in this protocol.

Information sources and search strategy

The search strategy will be developed under the guidance of a research librarian of Health Sciences from the University of Ottawa. A comprehensive search strategy using subject headings and keywords will be used to search for potentially eligible published studies in Medline (Ovid), Embase, and Web of Science. An initial search through the Medline (Ovid) database will be conducted using an analysis of text words found in the title and abstract, and the index terms used in describing the article (See a preliminary Medline search: S3 File). Secondly, keywords and index terms shall be identified to search for studies in selected databases. Finally, additional studies not found in the databases shall be searched from the reference lists of the selected studies from the first and second searches.

Additional searches will be conducted on the WHO, World Bank websites and the Centers for Disease Control and Prevention (CDC), The International Organization for Migration (IOM), The International Labour Organization (ILO) and the United Nations High Commissioner for Refugees (UNHCR) to search for unpublished studies. Search terms will include mobile, nomadic populations, migrant, internally displaced person, access to healthcare, neglected tropical diseases, NTDs, Africa, mass drug administration, MDA, care, movement, strategy. For grey literature search we will conduct manual searches by reviewing relevant reports, policy briefs, and technical documents available on institutional websites. This will involve navigating organizational repositories, and identifying relevant grey literature that may not be indexed in standard databases.

Zotero software will be used for citation management in this scoping review. The PRESS (Peer Review of Electronic Search Strategies) checklist will be used to ensure the rigor and accuracy of the search strategy for this scoping review.

The search strategy will specifically target the five WHO preventive chemotherapy NTDs of interest using relevant search terms that include but not limited to:

1. Lymphatic filariasis or elephantiasis or filarial or Wuchereria bancrofti or Brugia malayi or Brugia timori or microfilaria AND
2. Onchocerciasis or onchocerca volvulus or river blindness or onchocerciasis or volvulus AND
3. Schistosomiasis or Schistosoma haematobium or Schistosoma intercalatum or Schistosoma guineensis or Schistosoma mansoni or bilharzia or Katayama fever or snail fever AND
4. Soil-transmitted helminthiasis (STH) or Ascaris lumbricoides or Trichuris trichiura or Ancylostoma or Necator americanus or roundworm or whipworm or hookworm AND
5. Trachoma or Chlamydia trachomatis or trachoma or granular conjunctivitis AND

Moreover, population mobility-related terms such refugee, pastoralist, cross-border, internally displaced persons (IDPs), economic migrant, transhumance, nomad, migrant population, migrant worker, and population dynamics will be included to further focus and refine the search.

Study selection and screening process

Prior to the study’s commencement we will ensure that all team members have a shared interpretation of the inclusion and exclusion criteria, as well as how unclear information will be assessed by multiple team members. In some cases where questions remain concerning a particular study, efforts will be made to contact the authors for clarification to resolve ambiguities.

Studies will be identified in searched databases and saved in Zotero and exported to Covidence for screening. After importing references and inclusion/exclusion criteria into Covidence, two independent reviewers will screen titles and abstracts of included studies. All conflicts between the two reviewers will be resolved by a third reviewer. Once potentially eligible studies have been selected, this same procedure will be applied for full text screening. We will hold a briefing session with all reviewers on the screening process and the steering of inclusion/exclusion criteria and conflict resolution. We will be meeting regularly to discuss progress, address any difficulties, and explore ways to collaborate effectively.

Assessment of study quality

Unlike systematic reviews, a formal quality assessment is optional in scoping reviews, which are intended to map the extent and nature of evidence on a broad topic. However, the team will assess and discuss the quality of the studies informally, in order to avoid giving undue weight to the results of what we consider to be a lower quality study. For example, if a study is purely descriptive of only a few people or does not describe aspects of the study in a way considered rigorous by the team, we will highlight this when reporting on that study

Data charting, collection and extraction procedures

Two independent reviewers will extract data using a Microsoft Excel spreadsheet adopted from the Joanna Briggs Institute’s template for data extraction (S2 File) [44,45]. The template will be piloted on three articles before use. The following information will be gathered: (i) study characteristics, such as the name of the first authors, the year of publication, the country, and the study design; (ii) details about interventions that were put into place, such as implementation strategies, factors that helped or hindered the implementation of rural pipeline programs, and the results or impacts of those programs; (iii) reasons for movement and patterns of movement of mobile populations, the consequences on health outcomes and the approaches being developed to overcome these issues among mobile and migrant populations. In line with our review questions, both quantitative and qualitative data will be collected and analyzed. We will resolve discrepancies by consensus, or a third reviewer will be required. The rules for data extraction will be documented and stored with the protocol and template at the research data storage facility of ICERMali at the University of Sciences, Techniques and Technologies of Bamako (USTTB) in Mali.

We will include specific data extraction fields focusing on mobile populations, MDA interventions, and effectiveness outcomes. For mobile populations, fields will capture demographic data (e.g., age, gender, socio-economic status), migration patterns (e.g., seasonal, nomadic, cross-border movement), and risk factors (e.g., exposure to disease vectors, access to healthcare). For MDA interventions, we will document intervention types (e.g., mass drug administration, targeted treatment), delivery methods (e.g., door-to-door, fixed-site, mobile teams), coverage rates (e.g., proportion of population reached), and community engagement strategies (e.g., awareness campaigns, local health worker involvement). Effectiveness outcomes will include treatment compliance rates, disease prevalence reduction, and any reported adverse effects or treatment failures.

Synthesis and presentation of results

Extracted data will be reported in tables and/or figures. Further formats can be considered at the time of analysis. The results of this scoping review will be descriptive, including an explanation of their study characteristics with reference to study population on which they focus.

We will summarize the characteristics of included studies in a descriptive way. With an emphasis on mapping important concepts, populations, and features, we will compile and display the extracted data descriptively according to JBI recommendations [46]. We will report the results in text, tables and graphs following PRISMA-ScR guidelines.

Expected outcomes of the study

It is expected that the results of this study will reveal a low proportion of non-compliance and access to MDA among mobile and migrant populations. It is also expected that the results will reveal a relationship between the socio-demographic/structural characteristics of participants and MDA participation among mobile populations in Africa. We also anticipate that this study will determine why some people missed treatment and what recommendations are needed to improve MDA coverage rates in MMPs in Africa We will attempt to highlight evidence from the literature on the health status of mobile populations and to assess the best ways to provide them with MDA campaigns.

Potential limitations

This review may have limitations related to the search strategy. The inclusion of only studies published in French and/or English, as well as the specific search terms used, may reduce the sensitivity in identifying relevant studies. This study may also suffer from publication bias.

We will work with stakeholders and experts, if necessary, to find unpublished studies and incorporate studies in English and French to capture the most relevant content in order to reduce publication and language bias. The inclusion of studies in English and French is justified by the fact that these languages are frequently used in worldwide research, especially in the study’s target regions, like West Africa, guaranteeing thorough coverage of important studies. Furthermore, the writers’ fluency in both languages enables proper literature interpretation and analysis.

Ethics statement and dissemination of results

This protocol is part of a thesis protocol. We received ethical clearance from the University of Sciences, Techniques, and Technologies of Bamako’s Ethical Review Committee (Approval No. 2023/11/CE/USTTB), Mali, and from the Health Sciences and Sciences Research Ethics Board of the University of Ottawa (Approval No. H- 02- 23- 8759). This specific scoping review relies on studies already published or in the public domain and therefore does not require ethical approval. However, all measures will be taken to respect the procedures of scientific integrity.

The results of this study will be used in collaboration with program managers to strengthen the elimination or control of NTDs in Africa. The dissemination of the results of the scoping review will be done through peer review publication, presentation at conferences and other relevant stakeholder fora.

Status and timeline of the study

The scoping review will be conducted over a six-month period, from February to July 2025 (Table 1).

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Table 1. Activities and timeline of the study.

https://doi.org/10.1371/journal.pone.0324949.t001