Impact of Onchocerciasis Control on Visual Outcomes in Communities of Edo State: A Programme Review

Decades of ivermectin mass drug administration have transformed the prognosis of onchocerciasis, yet the impact of control programmes on visual outcomes in endemic communities of Edo State requires systematic programme-level evaluation. This study reviews the impact of onchocerciasis control activities on visual outcomes in endemic communities in Edo State, South South Nigeria. A retrospective programme review design will be adopted, utilising available data from three periodic epidemiological impact assessment surveys conducted in 2018, 2020, and 2023 in communities along the Ikpoba and Osse river systems. Indicators reviewed will include community microfilarial load, prevalence of blindness attributable to onchocerciasis, prevalence of visual impairment, coverage rates of community-directed treatment with ivermectin (CDTI), and community-level awareness of the programme. Trend analysis will be conducted to quantify changes over the assessment periods. Despite significant reductions in onchocerciasis burden nationally, some Edo State forest communities continue to show active transmission, attributed to high vector density, sub-optimal CDTI coverage, and migration of untreated individuals. This review provides evidence for Edo State Public Health Department and Sightsavers Nigeria on the residual burden and programme performance. Recommendations will address coverage mapping, community sensitisation to improve ivermectin uptake, integration with vector control activities, and strengthening of the Community-Directed Intervention mechanism at ward level. Keywords: onchocerciasis control, ivermectin, visual outcomes, Edo State, CDTI programme