Persistence of emerging viral fecal indicators in large-scale freshwater mesocosms

Abstract

Fecal indicator bacteria (FIB) are typically used to monitor microbial water quality but are poor representatives of viruses due to different environmental fate. Viral fecal indicators have been proposed as alternatives to FIB; however, data evaluating the persistence of emerging viral fecal indicators under realistic environmental conditions is necessary to evaluate their potential application. In this study, we examined the persistence of five viral fecal indicators, including crAssphage and pepper mild mottle virus (PMMoV), and three bacterial fecal indicators ( E. coli , enterococci and HF183/BacR287) in large-scale experimental ponds and freshwater mesocosms. Observed inactivation rate constants were highly variable and ranged from a minimum of −0.09 d −1 for PMMoV to a maximum of −3.5 d −1 for HF183/BacR287 in uncovered mesocosms. Overall, viral fecal indicators had slower inactivation than bacterial fecal indicators and PMMoV was inactivated more slowly than all other targets. These results demonstrate that bacterial fecal indicators inadequately represent viral fate following aging of sewage contaminated water due to differential persistence, and that currently used fecal indicator monitoring targets demonstrate highly variable persistence that should be considered during water quality monitoring and risk assessment.

Sewage surveillance for SARS-CoV-2: Molecular detection, quantification, and normalization factors

“…To assess the congruency of viral RNA content in wastewater with clinical cases, [ 15 ] built a model that included additional factors of high ambiguity and variability, such as rate of flow and per capita wastewater output, and viral rate of shedding. Several normalizing strategies are studied to adjust for the variation in faecal material induced by dilution, primarily using the two most familiar human faecal viral indicators (i.e., cross-assembly phage (crAssphage) and pepper mild mottle virus (PMMoV)) [ 16 ]. There are several limiting conditions in the detection of the novel coronavirus in wastewater systems.…”

Wastewater-based epidemiology for tracking COVID-19 trend and variants of concern in Ohio, United States

“…To account for the varying estimated fecal load over time and possible dilution due to rain, two human-specific fecal viruses, PMMoV and crAssphage, were quantified from Columbus wastewater to normalize the SARS-CoV-2 concentrations. These two viruses have been used as an internal reference for method validation due to their high persistence in water compared to other bacteria fecal indicators (25). Wastewater from the two Columbus sewersheds are a combined sewer (Table 1), which is more prone to dilution by stormwater events.…”

Metagenome-based comparisons of decay rates and host-specificity of fecal microbial communities for improved microbial source tracking

“…Caution is needed, however, to extrapolate these results to all habitats, as some aquatic habitats or environmental conditions are known to support long-term survival of both pathogens and FIB (43). Furthermore, there are only a few studies to date reporting decay rates of viral markers and pathogens in the environment (44, 45) for evaluation against the MAG decay kinetics reported here; hence, viral pathogens may deviate from these decay patterns.…”

“…Furthermore, there are only a few studies to date reporting decay rates of viral markers and pathogens in the environment (44,45) for evaluation against the MAG decay kinetics reported here; hence, viral pathogens may deviate from these decay patterns.…”