A probabilistic and epidemiological assessment of health risks associated with recreational exposure to contaminated surface water : a case of the uMsunduzi River

Abstract

Water quality degradation and scarcity have become prominent global concerns. In South Africa, poorly treated effluent from wastewater treatment facilities has contributed to the deterioration of river water quality, often exhibiting elevated levels of microorganisms. This study evaluated the microbial water quality of the uMsunduzi River and established a correlation between exposure to the river and the incidence of diarrheal infections among Dusi Marathon participants. In addition, the study conducted a theoretical assessment of the pre-and post-exposure risk reduction interventions that have the potential to safeguard participants of the canoe race The study employed a comprehensive approach, which included a water quality analysis using Escherichia coli, Pseudomonas aeruginosa, and Cryptosporidium spp. as reference pathogens. The detection of E. coli and P. aeruginosa was conducted using IDEXX Colilert-18 and Pseudolert detection and enumeration kits, and digital droplet Polymerase Chain Reaction (ddPCR) for Cryptosporidium spp. An exposure and diarrheal incidence assessment through a prospective survey methodology and a Quantitative Microbial Risk Assessment (QMRA). Data analysis and interpretation for the exposure and incidence assessment were accomplished using the most recent IBM® SPSS® VERSION 27. The probability analysis for the QMRA was conducted using the distribution fitting capability included in the @Risk 7.5 program developed by Palisade Corporation. The study detected elevated levels of E. coli, Pseudomonas aeruginosa, and Cryptosporidium spp. in the river water, exceeding acceptable limits set by World Health Organization and Department Water Affairs and Forestry. The exposure diarrheal incidence assessment revealed a significant association between river exposure and diarrheal infections, with a 97% increased risk of developing diarrhea among those who ingested water from the river. The QMRA indicated a significant risk of infection for populations who depend on the uMsunduzi River for recreational activities, primarily associated with Cryptosporidium spp. The conclusions drawn suggest that regular monitoring is crucial to ensure the safety of water for leisure activities such as swimming, boating, and fishing. Monitoring systems may identify possible health threats and apply appropriate mitigation actions by testing for pathogens, biological contaminants, and chemical pollutants. Recreational bodies of water may act as a reservoir for waterborne infections, offering significant health risks to persons. This primary data analysis provided a comprehensive overview of the incidence of diarrhea among Duzi Canoe Marathon participants in 2022. We identified participant demographics and exposure assessments, key factors contributed to this health concern. As the Duzi Canoe Marathon continues to attract diverse participants, understanding and addressing health challenges is paramount. This analysis is a valuable resource for future event planning and underscores the commitment to participant welfare.