Epidemiological Transition in Malaria Transmission Following Intensified Vector Control in Urban Abuja

Understanding the epidemiological transition in malaria transmission following intensified vector control provides critical evidence for adaptive programme management in rapidly urbanising cities with heterogeneous intervention coverage. This longitudinal ecological study characterised malaria transmission trends in Abuja Municipal Area Council across three phases: pre-intervention (2019 to 2020), during intensified vector control (2021 to 2022), and post-intensification (2023 to 2024). Health facility malaria case records from 25 sentinel sites were analysed alongside entomological data from 10 fixed mosquito collection points. Intervention coverage data including insecticide-treated net distribution and indoor residual spraying were obtained from programme records. Interrupted time series analysis was applied to assess intervention impact on malaria case counts. Confirmed malaria cases declined by 34.7 percent during intensified vector control and remained 28.2 percent below pre-intervention baseline at 12 months post-intensification. Anopheles density declined significantly in indoor residual spraying-covered zones but rebounded to 68 percent of baseline in non-sprayed peri-urban clusters. Children under five years experienced the greatest proportional case reduction. Persistent hotspots were identified in informal settlements with low net utilisation. The study demonstrates measurable transmission reduction and identifies coverage gap-driven hotspot persistence as the primary obstacle to sustained urban malaria control in Abuja. Keywords: malaria epidemiology, urban malaria, vector control, interrupted time series, Abuja.