Microbial and Parasitic Contamination, Associated Health Risks, and Control Strategies in Wastewater-irrigated Food Systems in Bayelsa State, Nigeria

Abstract

Wastewater use in agriculture is increasing, particularly in developing regions, but it poses serious food safety and public health risks due to microbial and parasitic contamination. This study assessed contamination levels, associated health risks, and control strategies in wastewater-irrigated systems using a cross-sectional laboratory-based approach. A total of 90 samples (wastewater, soil, and vegetables) were collected in Yenagoa, Bayelsa State, and analyzed using standard microbiological and parasitological methods. Public health risks were evaluated based on WHO guidelines, while statistical analyses included ANOVA, chi-square, correlation, and multiple regression. Results showed that wastewater had the highest microbial load, with total coliform counts of (3.45 ± 0.12) × 10⁵ CFU/mL, followed by vegetables and soil. Risk assessment classified wastewater (92.6%) and vegetables (88.9%) as very high risk. Escherichia coli was the most prevalent pathogen, while Ascaris lumbricoides was the dominant parasite. Gastroenteritis was the most frequently associated disease outcome. Significant associations were observed between pathogens and disease conditions (χ² = 14.62, p < 0.001). Regression analysis identified wastewater contamination as the strongest predictor of public health risk (β = 0.61; R² = 0.859). Among control measures, wastewater treatment achieved the highest microbial reduction (91.2%), while policy enforcement showed the greatest potential for risk reduction (72.3%). This study provides a novel, integrated evaluation linking contamination levels, disease risks, and intervention effectiveness within a single framework, offering practical insights for improving food safety in wastewater-irrigated systems. Strengthening wastewater treatment, adopting safer irrigation practices, and enforcing policies are essential.