Citation:

Wu, H., M. Juel, S. Eytcheson, T. Aw, M. Munir, AND M. Molina. Temporal and spatial relationships of CrAssphage and enteric viral and bacterial pathogens in wastewater in North Carolina. WATER RESEARCH. Elsevier Science Ltd, New York, NY, 239:120008, (2023). https://doi.org/10.1016/j.watres.2023.120008

Impact/Purpose:

The findings of this research can provide baseline information for bacterial and viral pathogens surveillance, quantitative microbial risk assessment, and strategies for pathogen removal during treatment processes. These results can also inform microbial modeling efforts and enhance prediction of the impact of wastewater pathogens on surface waters due to increased flooding events associated with climate change. The data provided by our study may help enhance water quality models, such as SWMM, to more accurately monitor the transport of viral pathogens in surface waters impacted by SSO and CSO events.

Description:

Enteric disease remains one of the most common concerns for public health. Wastewater treatment plants (WWTPs) receive domestic wastewater from sewer catchments and represent a snapshot of the enteric diseases that are circulating within the serving population, mirroring community health status. Untreated wastewater contains pathogens such as bacteria, virus, fungus, and parasites, and serve as reservoir and source of microbial contamination. Characterization of the temporal and spatial variations of the leading enteric pathogens prevalent in wastewater is critical to understand pathogen dynamics and facilitate the prediction of enteric disease outbreaks. However, direct identification of viral and bacterial enteric pathogens can be difficult and resource intensive, therefore, one approach that can help characterizing pathogen variability is to identify and use microbial indicators that are highly correlated with common enteric viral and bacterial pathogens, are easy to measure, and readily available in wastewater. In this study, we conducted weekly samplings from January 2021 through February 2022 in four wastewater treatment plants in North Carolina, USA with serving populations ranging from 80,000 to 200,000 residents. Samples were processed using hollow fiber ultrafiltration, followed by secondary concentration methods. Six microbial contaminants from the Contaminant Candidate List (CCL4), adenovirus, norovirus, enterovirus, Salmonella, Shiga toxin 2 (stx2), Campylobacter, in addition to the novel human-specific sewage indicator crAssphage (C64) were measured by quantitative polymerase chain reaction (qPCR) and reverse transcription qPCR (rt-qPCR) for DNA and RNA targets, respectively. Our results reveal that viral pathogens were more prevalent than bacterial pathogens in untreated wastewater. Significant correlations were observed between crAssphage and human adenovirus, enterovirus, norovirus, Salmonella, and Campylobacter (p<0.01). Pathogens and crAssphage concentrations in untreated wastewater showed distinct seasonal patterns, with peak concentrations of crAssphage in fall and winter, along with the viral etiological agents, while bacterial pathogens showed peaked concentrations in either winter (Campylobacter), fall (Salmonella), or summer (Stx2). Stx2 was the only target that showed a significant spatial difference among the four WWTPs. This study supports efforts to understand the ecology of wastewater pathogens to establish baseline concentrations and assessment of disease outbreaks and thus, moving forward a wastewater surveillance system for early warning and monitoring. The findings of this study can also inform microbial modeling efforts and enhance prediction of the impact of wastewater pathogens on surface waters due to increased flooding events and sewage overflows associated with climate change.

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