Antecedent Rainfall Impacted Levels of Enteric Bacteria and Opportunistic Bacterial Pathogens in Coastal Recreational Water in Araromi, Nigeria

Abstract

This study assessed pollution levels, environmental factors, and health risks of enteric bacterial pathogens in tropical coastal water in Araromi, Nigeria. We collected water samples from the beach over 12 months and determined the bacteria load in the samples using the membrane filtration technique. We determined the physicochemical characteristics of the samples using standard methods and measured antecedent rainfall using a weather station close to the beach. We assessed the association between the microbial and environmental data and estimated the risks of infections using dose-response models. Results showed that Salmonella had the highest (3.31 log₁₀ CFU/100 ml) mean value, indicating a potential health risk from Salmonella contamination. In contrast, Clostridium perfringens had the lowest (2.45 log₁₀ CFU/100 ml) mean value in water samples. The mean water temperature was 27.2℃, and the average pH was 7.3. Nitrate content ranged from 2.5 to 12.7 mg/L, whereas rainfall ranged from 21.3 to 385.1 mm, and it had the highest impact on the concentration of enumerated bacteria. The risk of infection with Campylobacter, Salmonella and Shigella were 0.012, 0.0031 and 0.017, respectively, higher than the acceptable risk threshold of 0.0001. Implementing pollution prevention measures, particularly targeting rainfall-induced contamination, is critical to ensure the safety of coastal recreational water.