Quantitative microbial risk assessment for waterborne pathogens in a wastewater treatment plant and its receiving surface water body

Abstract

Background Access to safe water for drinking and domestic activities remains a challenge in emerging economies like South Africa, forcing resource-limited communities to use microbiologically polluted river water for personal and household purposes, posing a public health risk. This study quantified bacterial contamination and the potential health hazards that wastewater treatment plant (WWTP) workers and communities may face after exposure to waterborne pathogenic bacteria in a WWTP and its associated surface water, respectively. Results Escherichia coli (Colilert®-18/ Quanti-Tray® 2000) and enterococci (Enterolert®/ Quanti-Tray® 2000) were quantified and definitively identified by real-time polymerase chain reaction targeting the uidA and tuf genes, respectively. An approximate beta-Poisson dose-response model was used to estimate the probability of infection (Pi) with pathogenic E. coli. Mean E. coli concentration ranged from 2.60E+ 02/100 mL to 4.84E+ 06/100 mL; enterococci ranged from 2.60E+ 02/100 mL to 3.19E+ 06/100 mL across all sampled sites. Of the 580 E. coli isolates obtained from this study, 89.1% were intestinal, and 7.6% were extraintestinal pathogenic E. coli. The 579 enterococci obtained were 50.4% E. faecalis (50.4%), 31.4% E. faecium, 3.5%, E. casseliflavus and 0.7% E. gallinarum. The community health risk stemming from the use of the water for recreational and domestic purposes revealed a greater health risk (Pi) from the ingestion of 1 mL of river water from upstream (range, 55.1–92.9%) than downstream (range, 26.8–65.3%) sites. The occupational risk of infection with pathogenic E. coli for workers resulting from a once-off unintentional consumption of 1 mL of water was 0% (effluent) and 23.8% (raw influent). Multiple weekly exposures of 1 mL over a year could result in a Pi of 1.2 and 100% for the effluent and influent, respectively. Conclusion Our findings reveal that there is a potentially high risk of infection for WWTP workers and communities that use river water upstream and downstream of the investigated WWTP.

Spectrum of Diarrheagenic Escherichia coli in Drinking and Wastewater in Rafha City of Saudi Arabia

“…The percentage of the EPEC positive samples were very low in our study (2%) which is in accordance with the study reported by Mbanga et al, 2020 (1.7 %) [30]. Osińska et al [31]. however, reported 65% EPEC from raw and processed wastewater from a WWTP in Poland.…”

“…The prevalence of EAEC in our study was also very low (2%) whereas Mbanga et al, 2020, [30] reported 53.3% prevalence of EAEC in samples taken from WWTP which is even higher than that reported by Osińska et al [31] 28%.…”

Genomic Insights of Multidrug-Resistant Escherichia coli From Wastewater Sources and Their Association With Clinical Pathogens in South Africa

“…All reactions included a no-template control consisting of the reaction mixture. The real-time PCR protocol was done according to Mbanga et al (10). The primers, virulence genes, and reference strains used to determine pathotypes are shown in Supplementary Table 1.…”

A scientometric study on quantitative microbial risk assessment in water quality analysis across 6 years (2016–2021)

“…The trend is attributable to high water demand due to population growth, poor infrastructure to harvest water the resource and manage its demand, as well as the resultant wastewater (Fuhrimann et al 2016;Nyika & Onyari 2019;Oki & Quiocho 2020). The pressure is even more in urban and suburban areas with no wastewater management systems and therefore, the population resort to release raw effluent to freshwater bodies resulting in a bigger pollution problem on such resources (Mbanga et al 2020).…”