Expanding Access to Preventive Chemotherapy Among Mobile and Migrant Populations

Neglected tropical diseases (NTDs) are among the most common groups of diseases globally, affecting more than one billion people and disproportionately burdening remote, underserved, and marginalized populations. The World Health Organization (WHO) broadly classifies most NTDs into two categories based on their recommended management approaches. Case-management NTDs-including Buruli ulcer, human African trypanosomiasis, rabies, Guinea worm disease, lymphoedema, leprosy, trichiasis, leishmaniasis, yaws, dengue, and mycetoma-require individualized diagnosis and treatment because of management complexity or the absence of effective large-scale diagnostic and therapeutic tools. In contrast, preventive chemotherapy NTDs (PC-NTDs), such as onchocerciasis, schistosomiasis, lymphatic filariasis, trachoma, and soil-transmitted helminthiasis, are primarily controlled through mass drug administration (MDA) delivered to at-risk populations to reduce morbidity and interrupt transmission. Other NTDs that do not neatly fit within these categories, such as rabies, snakebite envenoming, and dengue, require alternative prevention and control approaches. In many endemic countries, PC-NTDs constitute the largest proportion of the NTD burden and therefore have well-established control programs.

Over the last decade, NTDs have increasingly gained recognition as a major global health priority, culminating in the WHO NTD Road Map 2021-2030, which outlines ambitious targets for the control, elimination, or eradication of all NTDs in alignment with the Sustainable Development Goals. Despite these commitments, progress toward achieving the 2030 elimination targets for several PC-NTDs remains insufficient. In the African Region, where more than 40% of the global NTD burden is concentrated, only 19 of 54 countries had eliminated at least one NTD as of 2025. Persistent gaps in intervention coverage among vulnerable and underserved populations continue to threaten progress toward NTD elimination goals. Several programmatic bottlenecks have been identified, including but not limited to poor community awareness, perceived severity of the disease, perceived benefits of interventions, inadequate human and financial resources for programming, conflict and insecurity, political instability, and increasing migration and population mobility. While many of these barriers have received considerable global attention, migration and population mobility are increasingly emerging as critical yet understudied challenges. Population movement may occur because of conflict, insecurity, environmental pressures, seasonal labor, or other livelihood-related factors (trade, pastoralism, fishing, leisure, schooling), all of which may disrupt access to routine public health interventions. However, the specific implications of migration for MDA delivery, treatment continuity, and coverage remain poorly understood. Similarly, evidence-based strategies for optimizing PC-NTD programs among highly mobile and migrant populations remain limited.

Nigeria, the most populous country in sub-Saharan Africa, accounts for approximately one-quarter of the continent's NTD burden and has yet to eliminate any major NTD. For more than a decade, our team has collaborated with the Nigerian government and implementing partners to support NTD elimination efforts across the country. Although substantial progress has been made in reducing disease prevalence, improving morbidity management, and responding to outbreaks, migration continues to pose a major challenge to achieving optimal treatment coverage and has received limited attention within existing elimination strategies. Population movement within Nigeria and across neighboring borders are often driven by seasonal climatic patterns, insecurity and economic opportunities, and is facilitated by extensive river systems, trade corridors, grazing routes, and arable lands that sustain economic activities. These populations, herein referred to as mobile and migrant populations (MMPs), are frequently absent during MDA campaigns. Consequently, they often experience non-treatment, limited awareness of MDA activities, limited engagement with health-workers, and increasing community fatigue. Collectively, these dynamics may contribute to treatment refusals, sustain disease transmission, and slow progress toward elimination goals. The investigators therefore posit the need to improve MDA access, reach, and coverage among MMPs through approaches that strengthen involvement, trust, ownership, and the perceived value of MDA among MMPs that have historically been underrepresented in routine health programs.

This study aims to develop and evaluate a novel delivery model that utilizes community mapping and participatory research approaches to strengthen access to MDA among MMPs. The process will begin by generating a detailed understanding of migration realities, including migratory routes, movement timing, seasonal patterns, and key drivers of mobility, to identify where, when, and how MMPs move across different settings. The study will also explore the social and occupational networks that exist along these migratory pathways and assess how these networks can be strategically leveraged to expand MDA access and delivery. Ultimately, the overarching aim of the study is to evaluate whether this co-constructed delivery model can improve access, reach, and coverage of MDA among MMPs in Nigeria compared with standard delivery approaches. Specifically, the study will explore migratory routes, movement patterns, and drivers influencing participation in MDA; identify the social and occupational structures that shape mobility and access to healthcare; and examine how these existing networks can be strategically leveraged to improve MDA delivery, reporting, and community engagement. In addition, the study will assess the livelihood-linked incentives and complementary services prioritized by MMPs and evaluate how integrating these preferences into intervention design may strengthen demand for and participation in preventive chemotherapy programs. Finally, the study will examine the contextual, behavioral, and structural factors influencing implementation, while exploring how participatory processes foster trust, ownership, inclusivity, feasibility, sustainability, and scalability of the proposed delivery model across diverse migratory settings in Nigeria.

Inclusion criteria

Participants will be eligible for inclusion if they:

• Are children aged 5-14 years or adult heads of households residing in households identified as belonging to mobile or migrant populations.
• Reside permanently or semi-permanently within the study communities
• Have missed one or more previous rounds of onchocerciasis and/or lymphatic filariasis MDA.
• Are willing to provide the required biological specimens and participate in interviews, surveys, and participatory workshops or discussions as required by the study protocol.
• Provide informed consent or assent with parental/guardian consent where applicable for minors.

Exclusion criteria

Participants will be excluded if they:

• Are temporary visitors without meaningful residence in the study communities.
• Do not belong to the identified mobile or migrant populations targeted by the study.
• Are unable or unwilling to provide the required biological specimens or participate in study procedures.
• Decline informed consent or assent, or whose parent or guardian declines consent for participation.
• Are severely ill or have medical conditions that, in the opinion of study personnel, would make participation unsafe or inappropriate.