Spatio-Temporal Analysis of Tuberculosis in Anambra State, Nigeria Using GIS: Emerging Urban Clusters and the Role of Built-Up Environment (2013–2023)

Abstract

Tuberculosis (TB) remains a significant public health challenge in Nigeria, with transmission dynamics increasingly influenced by rapid urbanization and high human mobility. This study investigated the spatio-temporal trends of TB transmission across the 21 Local Government Areas (LGAs) of Anambra State from 2013 to 2023, focusing on the emergence of TB clusters and their association with urban development. Retrospective data were analyzed using Geographic Information Systems (GIS), incorporating TB case notifications, population projections, and Land Use/Land Cover (LULC) changes. Spatial cluster analysis was performed using Global Moran’s I, Local Indicators of Spatial Association (LISA), and Getis-Ord statistics, while multivariate regression assessed the impact of urbanization indicators. The study found that the Case Notification Rate (CNR) rose dramatically from 38.1 per 100,000 in 2013 to 183.7 per 100,000 in 2023, representing a 382.2% increase. The spatial distribution of TB shifted from a random pattern between 2013 and 2020 (p > 0.05) to a significantly clustered pattern from 2021 onward (Moran’s I = 0.208, p = 0.028), with hotspots concentrated in the heavily built-up and commercial LGAs of Onitsha North, Onitsha South, Awka South, and Nnewi North, as well as the rapidly expanding Onitsha–Idemili axis (including Obosi and Nkpor). Correlation analysis revealed that built-up area is moderately positively correlated with TB rate (r = 0.333), while population density shows a weaker positive relationship (r = 0.143). The multivariate regression model explained approximately 12.1% of the variation in TB incidence (R² = 0.121), identifying built-up area (beta = +0.320) as a stronger predictor than population density (beta = +0.100). These findings suggest that TB transmission is primarily driven by the structural and functional intensity of the urban environment; specifically high-mobility commercial hubs and transit axis, rather than raw population size alone. This highlights the need for public health interventions to target high-activity urban centers and commercial hotspots to effectively curb the TB burden in Anambra State.