System Dynamics Modelling of Neglected Tropical Disease Co-endemicity and the Case for Integrated Preventive Chemotherapy in North Central Nigeria

Multiple neglected tropical diseases are co-endemic across North Central Nigeria, including lymphatic filariasis, onchocerciasis, schistosomiasis, and soil-transmitted helminths, yet national programmes operate largely in silos, duplicating implementation costs and missing opportunities for synergistic drug delivery and health system efficiency gains. This doctoral research develops a system dynamics model of NTD co-endemicity and evaluates the epidemiological and economic case for integrated preventive chemotherapy in North Central Nigeria. Epidemiological data from sentinel surveillance surveys from six states including Benue, Kogi, Niger, Kwara, Nasarawa, and Plateau were compiled for all four target diseases for the period 2018 to 2023. A system dynamics model was constructed in Vensim, incorporating age-structured transmission dynamics, drug delivery logistics, health system capacity, and community compliance parameters for each disease. Scenarios comparing vertical single-disease delivery versus integrated multi-disease MDA platforms were simulated over a 10-year horizon. Cost-effectiveness analysis was conducted using a societal perspective, incorporating averted disability-adjusted life years, drug wastage reduction, and community mobilisation cost sharing. Evidence from 2020 to 2024 from integrated NTD programmes in Ethiopia and Ghana demonstrates cost savings of 30 to 50 percent through platform integration. This study generates Nigeria-specific modelling evidence and proposes an optimal integration roadmap for the Federal Ministry of Health. Original contributions include a dynamic NTD co-endemicity index and an integration cost-benefit calculator. Keywords: neglected tropical diseases, system dynamics modelling, integrated preventive chemotherapy, North Central Nigeria, co-endemicity.