Onchocerciasis Elimination Feasibility in Nigeria: A Geospatial Modelling and Health System Capacity Assessment Framework

Nigeria harbours the largest onchocerciasis disease burden globally, and establishing the feasibility of elimination as a public health problem by 2030 requires integrating geospatial epidemiological modelling with a rigorous assessment of the health system capacity required to sustain and intensify programme operations. This doctoral research develops an onchocerciasis elimination feasibility framework for Nigeria, combining geospatial modelling of transmission intensity with a mixed-methods health system capacity assessment. Parasitological survey data from 180 sentinel communities across 12 states were compiled from programme reports covering 2018 to 2023. Geostatistical kriging was used to generate national-level microfilariae prevalence surfaces and estimate the proportion of communities meeting WHO pre-elimination and elimination of transmission thresholds. The ONCHOSIM deterministic transmission model was calibrated to Nigerian epidemiological parameters and used to simulate elimination timelines under varying annual ivermectin coverage scenarios. In parallel, health system capacity was assessed through structured interviews with state NTD coordinators and programme managers across all six geopolitical zones, applying the WHO health system building blocks framework. Evidence from 2020 to 2024 identifies southeastern and north-central states as the furthest from elimination thresholds, with programme gaps including irregular drug supply and inadequate community distributor density. The study produces a state-by-state elimination readiness index and a prioritised investment roadmap. Findings will be presented to the Federal Ministry of Health and the WHO Regional Office for Africa. Keywords: onchocerciasis elimination, geospatial modelling, Nigeria, ONCHOSIM, health system capacity.