Geospatial assessment of household food safety risk and microbial contamination vulnerability in an urbanising Nigerian City

Abstract

Foodborne illnesses remain an important public health issue in fast-growing urban areas of Nigerian cities and household food safety knowledge and practices are anomalously distributed. In Ibadan metropolis social, economic, and environmental conditions may play a role in increasing household vulnerability to food safety risks, but these influences are not well understood spatially. This study was based on household-level questions about food safety knowledge, practices and contamination, and was driven by a desire to understand food safety vulnerabilities at the household level and how this state is affected by socioeconomic and environmental factors across the city. This cross-sectional study was conducted across 604 households in five Local Government Areas of Ibadan Metropolis using proportional multi-stage sampling. A structured questionnaire administered via REDCap with GPS-recorded household locations captured food safety knowledge, behaviours, and perceived control. A random subsample of 250 households (500 food contact surfaces) underwent microbiological assessment using ATP bioluminescence and Total Coliform testing; a matched comparison group of 50 households (100 surfaces) was included; this group was not a randomised or experimental control, so “comparison group” is used throughout to avoid implying an experimental design. Spatial distribution of food safety indicators and household vulnerability were mapped using ArcGIS 10, with vulnerability levels derived from an index-based framework adapted from Schwarz and Kuleshov. Across 604 households in Ibadan, food safety knowledge and practices showed clear spatial and socioeconomic disparities. Between 22 and 27% of households exhibited unsafe food handling behaviours, particularly in low-income areas with limited infrastructure. Only 28.9% had access to piped water, 46.5% had adequate kitchen facilities, and 39.7% accessed formal waste collection services. More than half (53.5%) prepared food in semi-open or outdoor spaces. Perceived control over food safety was lowest in Ibadan North East and Ibadan South East. Microbiological testing of 500 food contact surfaces showed 48.2% ATP failure (threshold: manufacturer-recommended RLU cutoff), compared to 18% in the comparison group. Total Coliform analysis revealed that 61.2% of tested food contact surfaces (306 of 500) were contaminated, with 42.4% classified as highly contaminated (≥ 100 CFU/cm²) and 38.8% undetected. Visually apparent co-occurrence (not tested using formal spatial statistics) suggested that low knowledge, unsafe behaviours, limited perceived control, and high contamination co-occurred in high-vulnerability neighbourhoods. Household food safety risks in Ibadan are influenced by multiple, interlinking socioeconomic and environmental factors that create distinct spatial patterns in vulnerability. The study provides insights into targeted, context-bound interventions focusing on high-risk neighbourhoods, addressing both knowledge gaps and structural limitations in household food safety practices. Strengthening community-based education, improving household food-handling environments, and engaging local stakeholders are important for curbing foodborne illness risks in rapidly growing urban settings. These findings provide empirical evidence from Nigeria to inform equitable and place-based food safety planning for urban households.