Epidemiologic evaluation of multiple alternate microbial water quality monitoring indicators at three California beaches

The use of faecal indicator organisms to manage microbial health risks in recreational waterways not impacted by point sources of sewage: a systematic review of the epidemiological evidence

This PRISMA review investigated the extent to which epidemiological evidence supports the use of faecal indicator organisms (FIOs) to manage microbial health risks in recreational waters without point sources of sewage. The quality of papers meeting the inclusion criteria was appraised using the Office of Health Assessment and Translation (OHAT) Risk of Bias tool and low-bias studies were synthesised. Studies consistently reported elevated illness risks (particularly gastrointestinal) among bathers compared with non-bathers. However, no FIOs or pathogens were associated consistently with any health outcomes. While enterococci most frequently correlated with a variety of illnesses, the relatively even split of positive and negative associations suggests an overall lack of association. Consequently, applying FIO guidelines derived from epidemiological studies with point sources of sewage could result in type I and type II errors. Overall, results suggest that the sources and drivers of health risks are site-specific. Tools including sanitary surveys, microbial source tracking, epidemiology and quantitative microbial risk assessment provide avenues for characterising site-specific health risks, for those who can afford them. Meanwhile, characterising the site-specific sources/drivers of contamination seems pragmatic as the limited evidence so far suggests that FIO monitoring may not be sufficient to protect health in these waters.

Bacterial community analysis of recreational beach waters reveals human fecal contamination and pathogenicity across varying field conditions

Assessing human fecal contamination of recreational beach waters is a public health challenge owing to multiple sources and environmental conditions affecting indicator, pathogen, and source marker relationships. Human fecal-associated markers, such as HF183, accurately indicate human waste, but reliance on individual markers risks false negative diagnoses, owing to marker source loading variations and attenuation. Bacterial community analysis is a data-dense approach that could improve the accuracy of human waste detection, but relatedness to actual human health hazards under complex coastal water conditions is unproven. Here, two Malibu and one Pacific Palisades, CA recreational beaches differing in urbanization and sewerage were studied over two years across varying seasonal rainfall, and beach berm, conditions. Fecal indicator bacteria (FIB), HF183, and human norovirus concentrations were quantified and related to bacterial community 16S rRNA gene sequences which were further analyzed for putative human pathogens and sewage proportions. All lower watersheds harbored human fecal sources, and surf zone contamination was enhanced by rainfall runoff with berm breaching, which intensified with urbanization. Notably, for sequenced surf zone waters sampled across all weather conditions (n = 36), sequence-based putative pathogen proportions correlated with qPCR HF183 concentrations (w/ and w/o PMA treatment; p = 0.0) and with human norovirus G1concentrations (p = 0.04) which also correlated with HF183 sequence abundance in bacterial communities (p = 0.02). Although human fecal sources appeared to vary seasonally and a range of physical conditions influenced surf zone fecal contamination, human fecal contamination and associated health hazard were reliably evidenced by bacterial community analysis in this study.

Cultured and molecular measures of fecal indicator microbes in Gulf of Mexico recreational waters

Recreational waters are routinely assessed by enumeration of fecal indicator bacteria, such as enterococci, but research suggests viral indicators may be better suited for recreational water quality applications. Somatic and F+ coliphage were proposed as predictors of viral pathogens in recreational waters, but concurrent measurements of enterococci and coliphages and comparisons across different risk-based beach action values (BAVs) are limited. We collected paired measurements of enterococci, E. coli, somatic and F+ coliphage from three Gulf of Mexico beaches. Enterococci (colony forming units: CFU) were enumerated on mEI agar and by qPCR (Entero1a: target sequence [TS]). E. coli was enumerated by qPCR (EC23S587, TS). Coliphages (plaque forming units: PFU) were enumerated using dead-end hollowfiber ultrafiltration and single agar layer assay. The largest correlation observed was between Entero1a and cultured enterococci (r ≥ 0.51, p ≤ 0.0001) and the smallest (r ≤ 0.01, p = 1.0) between F+ coliphage and cultured enterococci. Applying equivalent BAVs for culturable enterococci (60 CFU/100 mL), Entero1a (9658 TS per 100 mL) and suggested somatic (14 PFU/100 mL) and F+ (3 PFU/100 mL) thresholds resulted in the overall greatest agreement in beach advisory status between coliphages and Entero1a (74-82 %) and lowest between cultured enterococci and somatic coliphage (65 %). This rich data set not only provides valuable insights on the incidence of coliphage and FIB in the Gulf of Mexico but will also provide a foundation for future research on fecal source identification and water quality forecast modeling in sub-tropical marine waters.

Application of a microbial and pathogen source tracking toolbox to identify infrastructure problems in stormwater drainage networks: a case study

Water scarcity and increasing urbanization are forcing municipalities to consider alternative water sources, such as stormwater, to fill in water supply gaps or address hydromodification of receiving urban streams. Mounting evidence suggests that stormwater is often contaminated with human feces, even in stormwater drainage systems separate from sanitary sewers. Pinpointing sources of human contamination in drainage networks is challenging given the diverse sources of fecal pollution that can impact these systems and the non-specificity of traditional fecal indicator bacteria (FIB) for identifying these host sources. As such, we used a toolbox approach that encompassed microbial source tracking (MST), FIB monitoring, and bacterial pathogen monitoring to investigate microbial contamination of stormwater in an urban municipality. We demonstrate that human sewage frequently contaminated stormwater (in >50% of routine samples), based on the presence of the human fecal marker HF183, and often exceeded microbial water quality criteria. Arcobacter butzleri, a pathogen of emerging concern, was also detected in >50% of routine samples, with 75% of these pathogen-positive samples also being positive for the human fecal marker HF183, suggesting human municipal sewage as the likely source for this pathogen. MST and FIB were used to track human fecal pollution in the drainage network to the most likely point source of contamination, for which a sewage cross-connection was identified and confirmed using tracer dyes. These results point to the ubiquitous presence of human sewage in stormwater and also provide municipalities with the tools to identify sources of anthropogenic contamination in storm drainage networks.IMPORTANCEWater scarcity, increased urbanization, and population growth are driving municipalities worldwide to consider stormwater as an alternative water source in urban environments. However, many studies suggest that stormwater is relatively poor in terms of microbial water quality, is frequently contaminated with human sewage, and therefore could represent a potential health risk depending on the type of exposure (e.g., irrigation of community gardens). Traditional monitoring of water quality based on fecal bacteria does not provide any information about the sources of fecal pollution contaminating stormwater (i.e., animals/human feces). Herein, we present a case study that uses fecal bacterial monitoring, microbial source tracking, and bacterial pathogen analysis to identify a cross-connection that contributed to human fecal intrusion into an urban stormwater network. This microbial toolbox approach can be useful for municipalities in identifying infrastructure problems in stormwater drainage networks to reduce risks associated with water reuse.

Utilizing novel Escherichia coli-specific conserved signature proteins for enhanced monitoring of recreational water quality

Escherichia coli serves as a proxy indicator of fecal contamination in aquatic ecosystems. However, its identification using traditional culturing methods can take up to 24 h. The application of DNA markers, such as conserved signature proteins (CSPs) genes (unique to all species/strains of a specific taxon), can form the foundation for novel polymerase chain reaction (PCR) tests that unambiguously identify and detect targeted bacterial taxa of interest. This paper reports the identification of three new highly-conserved CSPs (genes), namely YahL, YdjO, and YjfZ, which are exclusive to E. coli/Shigella. Using PCR primers based on highly conserved regions within these CSPs, we have developed quantitative PCR (qPCR) assays for the evaluation of E. coli/Shigella species in water ecosystems. Both in-silico and experimental PCR testing confirmed the absence of sequence match when tested against other bacteria, thereby confirming 100% specificity of the tested CSPs for E. coli/Shigella. The qPCR assays for each of the three CSPs provided reliable quantification for all tested enterohaemorrhagic and environmental E. coli strains, a requirement for water testing. For recreational water samples, CSP-based quantification showed a high correlation (r > 7, p < 0.01) with conventional viable E. coli enumeration. This indicates that novel CSP-based qPCR assays for E. coli can serve as robust tools for monitoring water ecosystems and other critical areas, including food monitoring.

Somatic Coliphages as an Operational Tool to Assess Loss of Bathing Water Quality after Heavy Rain Events

Rapid population growth and coastal development has led to increased fecal contamination of coastal surface waters worldwide, enhancing the potential risk of waterborne human pathogens in bathing areas. More frequent heavy rainfall events, attributed to global warming, have further exacerbated the problem by causing sometimes sewer overflows into recreational waters. As traditional bacterial indicators have limited accuracy for predicting health risks associated with waterborne viruses, the additional use of viral indicators such as coliphages is recommended. In this study, we compared the behavior of bacterial and viral indicators of water quality at 10 Barcelona beaches during three bathing seasons, in dry conditions, and after four rainstorms that caused specific pollution events due to rain runoff with combined sewer overflows (CSO). Levels of all target indicators increased after the rainstorms, but compared to Escherichia coli and intestinal enterococci, somatic coliphages exhibited a slower decline and higher environmental persistence following a rain event. Daily continuous sampling carried out during the days following a rainstorm allowed not only the determination of the decay kinetics of each target indicator but also the day when the water quality recovered the values established in the current European regulation in approximately 2 -3 days after each CSO. These observations indicate that the combined use of bacterial and viral indicators can enhance the surveillance of microbial quality of bathing waters. Moreover, coliphages can swiftly provide insights into transient fecal pollution linked to rainfall episodes, thanks to available analytical techniques that enable same-day recommendations. The management of urban wastewater and recreational water regulations should consistently employ microbial indicators to address rainwater runoff or sewer overflows resulting from heavy rainfall.

Examining the influence of COVID-19 lockdowns on coastal water quality: A study on fecal bacteria levels in Moroccan seawaters

Fecal bacteria in bathing seawater pose a substantial public health risk and require rigorous monitoring. The unexpected beach closures during the COVID-19 lockdowns have afforded unique opportunities to evaluate the impact of human activities on bathing water quality (BWQ). This study examined the temporal changes in fecal coliforms (FC) and streptococci (FS) within bathing seawater across a popular coastal region in Morocco during two lockdown periods (2020 L and 2021 L), comparing these data with observations from pre-lockdown years (2018, 2019) and post-lockdown periods (2020, 2021, 2022). Our findings illuminate the influential role the hiatus periods played in enhancing bathing water quality, attaining an "excellent" status with marked reductions in fecal coliform and streptococci levels. Consequently, the FC/FS analysis exposed a clear preponderance of humans as the primary sources of fecal contamination, a trend that aligns with the burgeoning coastal tourism and the escalating numbers of beach visitors. Additionally, the presence of domestic animals like camels and horses used for tourist rides, coupled with an increase in wild animals such as dogs during the lockdown periods, compounded the potential sources of fecal bacteria in the study area. Furthermore, occasional sewage discharge from tourist accommodations and wastewater treatment plants may also contribute to fecal contamination. To effectively mitigate these concerns and bolster public health, a commitment to relentless surveillance efforts, leveraging novel and innovative tools, is essential. These findings underline the crucial interplay between human activities and the health of our coastal ecosystems, emphasizing the need for sustainable practices for a safer and healthier future.

Antimicrobial resistant Escherichia coli prevalence in freshwaters in Belgium and human exposure risk assessment

The objective of this work was to evaluate the antimicrobial resistant (AR) E. coli prevalence in recreational waters in Belgium and to assess the exposure risk for bathers. Nine stations were sampled during the 2021 bathing season. A total of 912 E. coli strains were isolated and tested by the disk diffusion method in accordance with EUCAST recommendations, including Extended-Spectrum Beta-Lactamase (ESBL) production. AR E. coli were counted at each bathing sites, 24% of strains were resistant to at least one antibiotic and 6% were Multi-Drug Resistant (MDR). A Multiple Antibiotic Resistance (MAR) index was calculated to compare the bathing sites. The Lesse river had the highest MAR index as well as the highest E. coli absolute abundance and the largest number of ESBL-producing E. coli. Conversely, the 3 lakes showed lower E. coli contamination levels and AR rates. A human health risk assessment of exposure to AR E. coli, based on the calculation of measured prevalence, was performed considering four different dose-response model scenarios. The human health risk (Pd) ranged from 10-9 to 0.183 (children). The exposure probabilities were low, except for scenario 3 (E. coli O157:H7), which is the most severe.

The Effect of Protozoa Indigenous to Lakewater and Wastewater on Decay of Fecal Indicator Bacteria and Coliphage

Fecal indicator bacteria (FIB: Escherichia coli and enterococci) are used to assess recreational water quality. Viral indicators (i.e., somatic and F+ coliphage), could improve the prediction of viral pathogens in recreational waters, however, the impact of environmental factors, including the effect of predatory protozoa source, on their survival in water is poorly understood. We investigated the effect of lakewater or wastewater protozoa, on the decay (decreasing concentrations over time) of culturable FIB and coliphages under sunlight and shaded conditions. FIB decay was generally greater than the coliphages and was more rapid when indicators were exposed to lake vs. wastewater protozoa. F+ coliphage decay was the least affected by experimental variables. Somatic coliphage decayed fastest in the presence of wastewater protozoa and sunlight, though their decay under shaded conditions was-10-fold less than F+ after 14 days. The protozoa source consistently contributed significantly to the decay of FIB, and somatic, though not the F+ coliphage. Sunlight generally accelerated decay, and shade reduced somatic coliphage decay to the lowest level among all the indicators. Differential responses of FIB, somatic, and F+ coliphages to environmental factors support the need for studies that address the relationship between the decay of coliphages and viral pathogens under environmentally relevant conditions.

Relationship between coliphage and Enterococcus at southern California beaches and implications for beach water quality management

Coliphage have been suggested as an alternative to fecal indicator bacteria for assessing recreational beach water quality, but it is unclear how frequently and at what types of beaches coliphage produces a different management outcome. Here we conducted side-by-side sampling of male-specific and somatic coliphage by the new EPA dead-end hollow fiber ultrafiltration (D-HFUF-SAL) method and Enterococcus at southern California beaches over two years. When samples were combined for all beach sites, somatic and male-specific coliphage both correlated with Enterococcus. When examined categorically, Enterococcus would have resulted in approximately two times the number of health advisories as somatic coliphage and four times that of male-specific coliphage,using recently proposed thresholds of 60 PFU/100 mL for somatic and 30 PFU/100 mL for male-specific coliphage. Overall, only 12% of total exceedances would have been for coliphage alone. Somatic coliphage exceedances that occurred in the absence of an Enterococcus exceedance were limited to a single site during south swell events, when this beach is known to be affected by nearby minimally treated sewage. Thus, somatic coliphage provided additional valuable health protection information, but may be more appropriate as a supplement to FIB measurements rather than as replacement because: (a) EPA-approved PCR methods for Enterococcus allow a more rapid response, (b) coliphage is more challenging owing to its greater sampling volume and laboratory time requirements, and (c) Enterococcus' long data history has yielded predictive management models that would need to be recreated for coliphage.

Microbiological assessment of marine and estuarine ecosystems using fecal indicator bacteria, Salmonella, Vibrio and antibiotic resistance pattern

Marine and estuarine environments are often affected by microbiological contamination that adversely affects their use and severely impacts human health. To examine the influence of anthropogenic activities, this study used two different ecosystems in Agadir Bay, to compare fecal indicator bacteria (FIB) and bacterial pathogen profiles over two years. Vibrio target pathogens were detected at a high frequency (49.3%), while a low percentage (5.5%) was noted for Salmonella. Apart from those mentioned above, several other pathogenic bacteria were detected such as Cronobacter sakzakii, Pseudomonas fluorescens, and Aeromonas hydrophila. We also investigated the antimicrobial resistance of the pathogenic bacteria isolated. Salmonella strains were sensitive to all the antibiotics used, except ampicillin, amoxicillin + Ac clavulanic and chloramphenicol. And Vibrio strains were resistant to ampicillin, cephalothin, amikacin, and ciprofloxacin. This study highlights the limitations of FIB in assessing the microbiological quality and the importance of environmental surveys in understanding the distribution of pathogens.

Neonatal calf diarrhea: A potent reservoir of multi-drug resistant bacteria, environmental contamination and public health hazard in Pakistan

Though emergence of multi-drug resistant bacteria in the environment is a demonstrated worldwide phenomenon, limited research is reported about the prevalence of resistant bacteria in fecal ecology of neonatal calf diarrhea (NCD) animals in Pakistan. The present study aimed to identify and assess the prevalence of bacterial pathogens and their resistance potential in the fecal ecology of NCD diseased animals of Pakistan. The presence of antibiotic resistance genes (blaTEM, blaNDM-1, blaCTX-M, qnrS) was also investigated. A total of 51 bacterial isolates were recovered from feces of young diarrheic animals (n = 11), collected from 7 cities of Pakistan and identified on the basis of 16S rRNA gene sequence and phylogenetic analysis. Selected isolates were subjected to antimicrobial susceptibility by disc diffusion method while polymerase chain reaction (PCR) was used to characterize the blaTEM, blaNDM-1, blaCTX-M, qnrS and mcr-1 antibiotic resistance genes. Based on the 16S rRNA gene sequences (Accession numbers: LC488898 to LC488948), all isolates were identified that belonged to seventeen genera with the highest prevalence rate for phylum Proteobacteria and genus Bacillus (23%). Antibiotic susceptibility explained the prevalence of resistance in isolates ciprofloxacin (100%), ampicillin (100%), sulfamethoxazole-trimethoprim (85%), tetracycline (75%), amoxicillin (55%), ofloxacin (50%), ceftazidime (45%), amoxicillin/clavulanic acid (45%), levofloxacin (30%), cefpodoxime (25%), cefotaxime (25%), cefotaxime/clavulanic acid (20%), and imipenem (10%). MICs demonstrated that almost 90% isolates were multi-drug resistant (against at least three antibiotics), specially against ciprofloxacin, and tetracycline with the highest resistance levels for Shigella sp. (NCCP-421) (MIC-CIP up to 75 μg mL-1) and Escherichia sp. (NCCP-432) (MIC-TET up to 250 μg mL-1). PCR-assisted detection of antibiotic resistance genes showed that 54% isolates were positive for blaTEM gene, 7% isolates were positive for blaCTX-M gene, 23% isolates were positive for each of qnrS and mcr-1 genes, 23% isolates were co-positive in combinations of qnrS and mcr-1 genes and blaTEM and mcr-1 genes, whereas none of the isolate showed presence of blaNDM-1 gene.

Quantitative Microbial Risk Assessment of Antimicrobial Resistant and Susceptible Staphylococcus aureus in Reclaimed Wastewaters

The annual risks of colonization, skin infection, bloodstream infection (BSI), and disease burden from exposures to antibiotic-resistant and susceptible Staphylococcus aureus (S. aureus) were estimated using quantitative microbial risk assessment (QMRA). We estimated the probability of nasal colonization after immersion in wastewater (WW) or greywater (GW) treated across a range of treatment alternatives and subsequent infection. Horizontal gene transfer was incorporated into the treatment model but had little effect on the predicted risk. The cumulative annual probability of infection (resulting from self-inoculation) was most sensitive to the treatment log₁₀ reduction value (LRV), S. aureus concentration, and the newly calculated morbidity ratios and was below the health benchmark of 10^-4 infections per person per year (ppy) given a treatment LRV of roughly 3.0. The predicted annual disability-adjusted life years (DALYs), which were dominated by BSI, were below the health benchmark of 10^-6 DALYs ppy for resistant and susceptible S. aureus, given LRVs of 4.5 and 3.5, respectively. Thus, the estimated infection risks and disease burdens resulting from nasal colonization are below the relevant health benchmarks for risk-based, nonpotable, or potable reuse systems but possibly above for immersion in minimally treated GW or WW. Strain-specific data to characterize dose-response and concentration in WW are needed to substantiate the QMRA.

A baseline study of spatial variability of bacteria (total coliform, E. coli, and Enterococcus spp.) as biomarkers of pollution in ten tropical Atlantic beaches: concern for environmental and public health

Coastal water quality in urban cities is increasingly impacted by human activities such as agricultural runoff, sewage discharges, and poor sanitation. However, environmental factors controlling bacteria abundance remain poorly understood. The study employed multiple indicators to assess ten beach water qualities in Ghana during minor wet seasons. Environmental parameters (e.g. temperature, electrical conductivity, total dissolved solids) were measured in situ using the Horiba multiple parameter probe. Surface water samples were collected to measure total suspended solids, nutrients, and chlorophyll-a via standard methods and bacteria determination through membrane filtration. Environmental parameters measured showed no significant variation for the sample period. However, bacteria loads differ significantly (p = 0.024) among the beaches and influenced significantly by nitrate (55.3%, p = 0.02) and total dissolved solids (17.1%, p = 0.017). The baseline study detected an increased amount of total coliforms and faecal indicator bacteria (Escherichia coli and Enterococcus spp.) in beach waters along the coast of Ghana, suggesting faecal contamination, which can pose health risks. The mean ± standard deviations of bacteria loads in beach water are total coliforms (4.06 × 10³ ± 4.16 × 10³ CFU/100 mL), E. coli (7.06 × 10² ± 1.72 × 10³ CFU/100 mL), and Enterococcus spp. (6.15 × 10² ± 1.75 × 10³ CFU/100 mL). Evidence of pollution calls for public awareness to prevent ecological and health-related risks and policy reforms to control coastal water pollution. Future research should focus on identifying the sources of contamination in the tropical Atlantic region.

Bathing Water Quality Monitoring Practices in Europe and the United States

Many countries including EU Member States (EUMS) and the United States (U.S.) regularly monitor the microbial quality of bathing water to protect public health. This study comprehensively evaluates the EU bathing water directive (BWD) and the U.S. recreational water quality criteria (RWQC) as regulatory frameworks for monitoring microbial quality of bathing water. The major differences between these two regulatory frameworks are the provision of bathing water profiles, classification of bathing sites based on the pollution level, variations in the sampling frequency, accepted probable illness risk, epidemiological studies conducted during the development of guideline values, and monitoring methods. There are also similarities between the two approaches given that both enumerate viable fecal indicator bacteria (FIB) as an index of the potential risk to human health in bathing water and accept such risk up to a certain level. However, enumeration of FIB using methods outlined within these current regulatory frameworks does not consider the source of contamination nor variation in inactivation rates of enteric microbes in different ecological contexts, which is dependent on factors such as temperature, solar radiation, and salinity in various climatic regions within their geographical areas. A comprehensive "tool-box approach", i.e., coupling of FIB and viral pathogen indicators with microbial source tracking for regulatory purposes, offers potential for delivering improved understanding to better protect the health of bathers.

Variable fecal source prioritization in recreational waters routinely monitored with viral and bacterial general indicators

Somatic and F+ coliphage methods are under consideration as potential routine surface water quality monitoring tools to identify unsafe levels of fecal pollution in recreational waters. However, little is known about the cooccurrence of these virus-based fecal indicators and host-associated genetic markers used to prioritize key pollution sources for remediation. In this study, paired measurements of cultivated coliphage (somatic and F+) and bacterial (E. coli and enterococci) general fecal indicators and genetic markers indicative of human (HF183/BacR287 and HumM2), ruminant (Rum2Bac), canine (DG3), and avian (GFD) fecal pollution sources were assessed in 365 water samples collected from six Great Lakes Basin beach and river sites over a 15-week recreational season. Water samples were organized into groups based on defined viral and bacterial fecal indicator water quality thresholds and average log10 host-associated genetic marker fecal score ratios were estimated to compare pollutant source inferences based on variable routine water quality monitoring practices. Eligible log10 fecal score ratios ranged from -0.051 (F+ coliphage, GFD) to 2.08 (enterococci, Rum2Bac). Using a fecal score ratio approach, findings suggest that general fecal indicator selection for routine water quality monitoring can influence the interpretation of host-associated genetic marker measurements, in some cases, prioritizing different pollutant sources for remediation. Variable trends were also observed between Great Lake beach and river sites suggesting disparate management practices may be useful for each water type.

Feature Extraction of Marine Water Pollution Based on Data Mining

The ocean occupies more than two-thirds of the earth’s area, providing a lot of oxygen and materials for human survival and development. However, with human activities, a large number of sewage, plastic bags, and other wastes are discharged into the ocean, and the problem of marine water pollution has become a hot topic in the world. In order to extract the characteristics of marine water pollution, this study proposed K-means clustering technology based on cosine distance and discrimination to study the polluted water. In this study, the polygonal area method combined with six parameters of water quality is used to analyze the marine water body anomalies, so as to realize the rapid and real-time monitoring of marine water body anomalies. At the same time, the cosine distance method and discrimination are used to classify marine water pollutants, so as to improve the classification accuracy. The results show that the detection rate of water quality anomalies is more than 88.2%, and the overall classification accuracy of water pollution is 96.3%, which proves the effectiveness of the method. It is hoped that this study can provide timely and effective data support for the detection of marine water bodies.

Examining coastal dynamics and recreational water quality by quantifying multiple sewage specific markers in a North Carolina estuary

Fecal contamination is observed downstream of municipal separate storm sewer systems in coastal North Carolina. While it is well accepted that wet weather contributes to this phenomenon, less is understood about the contribution of the complex hydrology in this low-lying coastal plain. A quantitative microbial assessment was conducted in Beaufort, North Carolina to identify trends and potential sources of fecal contamination in stormwater receiving waters. Fecal indicator concentrations were significantly higher in receiving water downstream of a tidally submerged outfall compared to an outfall that was permanently submerged (p < 0.001), though tidal height was not predictive of human-specific microbial source tracking (MST) marker concentrations at the tidally submerged site. Short-term rainfall (i.e. <12 h) was predictive of E. coli, Enterococcus spp., and human-specific MST marker concentrations (Fecal Bacteroides, BacHum, and HF183) in receiving waters. The strong correlation between 12-hr antecedent rainfall and Enterococcus spp. (r = 0.57, p < 0.001, n = 92) suggests a predictive model could be developed based on rainfall to communicate risk for bathers. Additional molecular marker data indicates that the delivery of fecal sources is complex and highly variable, likely due to the influence of tidal influx (saltwater intrusion from the estuary) into the low-lying stormwater pipes. In particular, elevated MST marker concentrations (up to 2.56 × 10⁴ gene copies HF183/mL) were observed in standing water near surcharging street storm drain. These data are being used to establish a baseline for stormwater dynamics prior to dramatic rainfall in 2018 and to characterize the interaction between complex stormwater dynamics and water quality impairment in coastal NC.

Antibiotic Resistance in Recreational Waters: State of the Science

Ambient recreational waters can act as both recipients and natural reservoirs for antimicrobial resistant (AMR) bacteria and antimicrobial resistant genes (ARGs), where they may persist and replicate. Contact with AMR bacteria and ARGs potentially puts recreators at risk, which can thus decrease their ability to fight infections. A variety of point and nonpoint sources, including contaminated wastewater effluents, runoff from animal feeding operations, and sewer overflow events, can contribute to environmental loading of AMR bacteria and ARGs. The overall goal of this article is to provide the state of the science related to recreational exposure and AMR, which has been an area of increasing interest. Specific objectives of the review include (1) a description of potential sources of antibiotics, AMR bacteria, and ARGs in recreational waters, as documented in the available literature; (2) a discussion of what is known about human recreational exposures to AMR bacteria and ARGs, using findings from health studies and exposure assessments; and (3) identification of knowledge gaps and future research needs. To better understand the dynamics related to AMR and associated recreational water risks, future research should focus on source contribution, fate and transport-across treatment and in the environment; human health risk assessment; and standardized methods.

Microbial Indicators of Fecal Pollution: Recent Progress and Challenges in Assessing Water Quality

PURPOSE OF REVIEW

Fecal contamination of water is a major public health concern. This review summarizes recent developments and advancements in water quality indicators of fecal contamination.

RECENT FINDINGS

This review highlights a number of trends. First, fecal indicators continue to be a valuable tool to assess water quality and have expanded to include indicators able to detect sources of fecal contamination in water. Second, molecular methods, particularly PCR-based methods, have advanced considerably in their selected targets and rigor, but have added complexity that may prohibit adoption for routine monitoring activities at this time. Third, risk modeling is beginning to better connect indicators and human health risks, with the accuracy of assessments currently tied to the timing and conditions where risk is measured. Research has advanced although challenges remain for the effective use of both traditional and alternative fecal indicators for risk characterization, source attribution and apportionment, and impact evaluation.

Assessment of health risks from recreational exposure to Giardia and Cryptosporidium in coastal bathing waters

Some Brazilian beaches are impacted by raw or poorly treated sewage. Thus, users (beachgoers, sports people, and children) are exposed to pathogens, which pose health concerns. This study aimed to estimate the probability of infection and disease by Giardia and Cryptosporidium, using the quantitative microbial risk assessment (QMRA), for three groups of bathers: children, adults, and open water swimmers. The concentrations of (oo)cysts were taken from a study run by CETESB (Environmental Company of Sao Paulo State) throughout 2011 and 2012, in which 203 samples were collected monthly and analyzed for (oo)cysts of Giardia and Cryptosporidium. Giardia was present in 43% of the samples, while Cryptosporidium in 13%. Infection probability was higher in beaches with more positive samples for Giardia cysts for the group of open water swimmers. In some cases, the highest annual risk obtained for giardiasis and cryptosporidiosis was 2.4 × 10^-1 and 8.9 × 10^-3 for open water swimmers, respectively, exceeding the incidence results found in the epidemiological study run in summer of 1999 in São Paulo state coast. The results bring insights to improve environmental quality in order to protect tourists' and residents' wellbeing.

Source-Associated Gastroenteritis Risk from Swimming Exposure to Aging Fecal Pathogens

Human contact with fecally contaminated waters often raises public health concern. The infection potential closely relates to the fecal source type and the aging persistence of waterborne pathogens. In this study, the health risk of contracting gastroenteritis from exposure to aging fecal contamination was predicted using source-associated markers. Microbial decay characteristics in typical summer seawater were incorporated into a pathogen dose estimation model for a constant fecal input. Results show that the median illness probability commensurate with the health benchmark of 36/1000 corresponded to the marker concentrations of ∼7.8, ∼6.6, ∼3.7, and ∼3.5 log₁₀ gene copies/100 mL for seagulls, cattle, raw sewage, and treated effluent, respectively. The error in risk estimates due to neglecting microbial decay was linearly correlated to the decay differences between markers and pathogens. Specifically, the health risk associated with nonhuman sources, which was primarily contributed by bacterial and parasitic pathogens, can be substantially overestimated, while that for virus-dominated human sources was insignificantly affected by the differential decay. Additionally, seagulls dominated the Enterococcus concentration in waters with a mixture of the above-mentioned sources, although they posed limited health risk. This study provides an approach to understanding the influence of fecal aging on health risk estimation.

Enteric viruses, somatic coliphages and Vibrio species in marine bathing and non-bathing waters in Italy

Microbial safety of recreational waters is a significant public health issue. In this study we assessed the occurrence and quantity of enteric viruses in bathing and non-bathing waters in Italy, in parallel with microbial faecal indicators, somatic coliphages and Vibrio spp. Enteric viruses (aichivirus, norovirus and enterovirus) were detected in 55% of bathing water samples, including samples with bacterial indicator concentrations compliant with the European bathing water Directive. Aichivirus was the most frequent and abundant virus. Adenovirus was detected only in non-bathing waters. Somatic coliphages were identified in 50% bathing water samples, 80% of which showed simultaneous presence of viruses. Vibrio species were ubiquitous, with 9 species identified, including potential pathogens (V. cholerae, V. parahaemoylticus and V. vulnificus). This is the first study showing the occurrence and high concentration of Aichivirus in bathing waters and provides original information, useful in view of a future revision of the European Directive.

Detection and occurrence of indicator organisms and pathogens

This review paper focuses on detection and quantification techniques of indicator organisms that can be used for water quality assessment. The environmental pathogens that are critical to understand and better evaluate water quality are also discussed in this paper. Several recent studies using culture-independent methods such as microbial source tracking, pulsed field gel electrophoresis, mitochondrial DNA, and next generation sequencing to assess various environmental samples and water bodies have been reviewed. PRACTITIONER POINTS: Various waterborne pathogens and cases of outbreak occurances due to presence of pathogens are studied in this review paper. Recent studies for detecting major indicator organisms to evaluate the presence of pathogens in water bodies are reviewed. Culture-independent techniques as robust tools to detect and quantify waterborne pathogens are discussed in this review paper.

Correlation among fecal indicator bacteria and physicochemical parameters with the presence of Helicobacter pylori DNA in raw and drinking water from Bogotá, Colombia

BACKGROUND

The quality of raw and drinking water is a matter of considerable concern due to the possibility of fecal contamination. To assess the quality and public health risk of different types of water, the fecal indicator bacteria (FIB) are used. However, some pathogens, such as Helicobacter pylori, may be present in water when FIB cannot be found. H pylori is recognized as the causative agent of chronic gastritis, peptic and duodenal ulcers, and gastric cancer. The aim of this study was to evaluate the relationships among physicochemical parameters, FIB concentrations, and the presence of H pylori DNA in raw and drinking water from Bogotá, Colombia.

MATERIALS AND METHODS

A total of 310 water samples were collected 1 day per week from July 2015 to August 2016, and physicochemical parameters (pH, turbidity, conductivity, and residual free chlorine) were measured. Presence of H pylori DNA was determined and quantified by quantitative polymerase chain reaction (qPCR). Fecal indicator bacteria (total coliforms, Escherichia coli, and spores of sulfite-reducing Clostridia) were enumerated by using standard culture techniques.

RESULTS

Thirty of 155 (31%) raw water samples and forty-eight of 155 (38.7%) drinking water samples were positive for the presence of H pylori. No statistically significant relationships were found between physicochemical parameters or FIB with the presence or absence of H pylori in any sample (P < 0.05).

CONCLUSIONS

This study provides evidence of the presence of H pylori DNA in raw and drinking water in Bogotá, and shows that the detection and enumeration of FIB and physicochemical parameters in water do not correlate with the risk of contamination with H pylori.

Storm runoff differentially influences the nutrient concentrations and microbial contamination at two distinct beaches in northern China

With the escalating coastal development and loss of vegetated landscape, the volume of storm runoff increases significantly in Chinese coastal cities. To protect human health and valuable recreational resources, it is necessary to develop a quantitative understanding of coastal pollution. Here we studied the influence of storm runoff on the nutrients and microbial pathogens at two popular bathing beaches in northern China. Dongshan Beach, located near the mouth of an urban river, is influenced by non-point source pollution while Tiger-Rock Beach, a coastal beach, is primarily influenced by a point source from a storm drain outfall. Storm runoff significantly (P < 0.001) decreased the salinity and Chl a post-storm at both the beaches, but only reduced the concentration of dissolved inorganic N at Tiger-Rock Beach. Escherichia coli decreased by 68.7% at Dongshan Beach, possibly due to the dilution effect of the stormflow, contradicting the notion of elevated fecal contamination in coastal beaches from storm runoff. Vibrio parahaemolyticus increased at both beaches post-storm, by 155.7% at Dongshan Beach and 136.7% at Tiger-Rock Beach. Regardless of storm impact, both E. coli and V. parahaemolyticus were much higher at Dongshan Beach than that at Tiger-Rock, suggesting the influence of different surrounding topographies. Lastly, the statistical models developed based on the environmental and microbial parameters regression showed predictive power (adjusted R² > 0.5) to estimate the concentration of E. coli at Dongshan Beach and V. parahaemolyticus at Tiger-Rock Beach. Overall, the results suggest the unique role of the individual beaches in attenuating the effect of rainfall on the concentration of microbial pathogens in bathing water quality and provide unique predictive models for recreational water management and public health protection.

Occurrence of coliphage in raw wastewater and in ambient water: A meta-analysis

Coliphage have been proposed as indicators of fecal contamination in recreational waters because they better reflect the persistence of pathogenic viruses in the environment and through wastewater treatment than traditional fecal indicator bacteria. Herein, we conducted a systematic literature search of peer-reviewed publications to identify coliphage density data (somatic and male-specific, or MSC) in raw wastewater and ambient waters. The literature review inclusion criteria included scope, study quality, and data availability. A non-parametric two-stage bootstrap analysis was used to estimate the coliphage distributions in raw wastewater and account for geographic region and season. Additionally, two statistical methodologies were explored for developing coliphage density distributions in ambient waters, to account for the nondetects in the datasets. In raw wastewater, the analysis resulted in seasonal density distributions of somatic coliphage (SC) (mean 6.5 log₁₀ plaque forming units (PFU)/L; 95% confidence interval (CI): 6.2-6.8) and MSC (mean 5.9 log₁₀ PFU/L; 95% CI: 5.5-6.1). In ambient waters, 49% of MSC samples were nondetects, compared with less than 5% for SC. Overall distributional estimates of ambient densities of coliphage were statistically higher for SC than for MSC (mean 3.4 and 1.0 log₁₀ PFU/L, respectively). Distributions of coliphage in raw wastewater and ambient water will be useful for future microbial risk assessments.

Relationships between Microbial Indicators and Pathogens in Recreational Water Settings

Fecal pollution of recreational waters can cause scenic blight and pose a threat to public health, resulting in beach advisories and closures. Fecal indicator bacteria (total and fecal coliforms, Escherichia coli, and enterococci), and alternative indicators of fecal pollution (Clostridium perfringens and bacteriophages) are routinely used in the assessment of sanitary quality of recreational waters. However, fecal indicator bacteria (FIB), and alternative indicators are found in the gastrointestinal tract of humans, and many other animals and therefore are considered general indicators of fecal pollution. As such, there is room for improvement in terms of their use for informing risk assessment and remediation strategies. Microbial source tracking (MST) genetic markers are closely associated with animal hosts and are used to identify fecal pollution sources. In this review, we examine 73 papers generated over 40 years that reported the relationship between at least one indicator and one pathogen group or species. Nearly half of the reports did not include statistical analysis, while the remainder were almost equally split between those that observed statistically significant relationships and those that did not. Statistical significance was reported less frequently in marine and brackish waters compared to freshwater, and the number of statistically significant relationships was considerably higher in freshwater (p < 0.0001). Overall, significant relationships were more commonly reported between FIB and pathogenic bacteria or protozoa, compared to pathogenic viruses (p: 0.0022⁻0.0005), and this was more pronounced in freshwater compared to marine. Statistically significant relationships were typically noted following wet weather events and at sites known to be impacted by recent fecal pollution. Among the studies that reported frequency of detection, FIB were detected most consistently, followed by alternative indicators. MST markers and the three pathogen groups were detected least frequently. This trend was mirrored by reported concentrations for each group of organisms (FIB > alternative indicators > MST markers > pathogens). Thus, while FIB, alternative indicators, and MST markers continue to be suitable indicators of fecal pollution, their relationship with waterborne pathogens, particularly viruses, is tenuous at best and influenced by many different factors such as frequency of detection, variable shedding rates, differential fate and transport characteristics, as well as a broad range of site-specific factors such as the potential for the presence of a complex mixture of multiple sources of fecal contamination and pathogens.

Viral tools for detection of fecal contamination and microbial source tracking in wastewater from food industries and domestic sewage

Alternative indicators may be more suitable than thermotolerant coliform bacteria to assess enteric virus pollution in environmental waters and their removal from wastewaters. In this study, F-specific RNA bacteriophages (F-RNAPh) showed to be potential viral indicators of fecal contamination when they were quantified from domestic and food-industrial effluents containing human, chicken, swine or bovine wastes. In addition, they showed to be resistant to the primary and secondary treatments of the wastewater treatment plants. The viable F-RNAPh count showed correlation with viable thermotolerant coliforms but also with human polyomaviruses (HPyV) quantified by a new molecular method. In domestic effluents, F-RNAPh and HPyV indicators significantly correlated with a human viral pathogen, norovirus, while the bacterial indicator did not, being then better predictors of the behavior of enteric pathogenic viruses. In addition, we assessed human, bovine and fowl microbial source tracking markers, based on the molecular detections of human polyomavirus, bovine polyomavirus, and fowl adenovirus, respectively. The techniques implemented extend the range of viruses detected, since they target different viral types simultaneously. These markers could be applied when multiple source pollution is suspected, contributing to making decisions on public health interventions.

Incidence of somatic and F+ coliphage in Great Lake Basin recreational waters

There is a growing interest for the use of coliphage as an alternative indicator to assess fecal pollution in recreational waters. Coliphage are a group of viruses that infect Escherichia coli and are considered as potential surrogates to infer the likely presence of enteric viral pathogens. We report the use of a dead-end hollow fiber ultrafiltration single agar layer method to enumerate F+ and somatic coliphage from surface waters collected from three Great Lake areas. At each location, three sites (two beaches; one river) were sampled five days a week over the 2015 beach season (n = 609 total samples). In addition, culturable E. coli and enterococci concentrations, as well as 16 water quality and recreational area parameters were assessed such as rainfall, turbidity, dissolved oxygen, pH, and ultra violet absorbance. Overall, somatic coliphage levels ranged from non-detectable to 4.39 log₁₀ plaque forming units per liter and were consistently higher compared to F+ (non-detectable to 3.15 log₁₀ PFU/L), regardless of sampling site. Coliphage concentrations weakly correlated with cultivated fecal indicator bacteria levels (E. coli and enterococci) at 75% of beach sites tested in study (r = 0.28 to 0.40). In addition, ultraviolet light absorption and water temperature were closely associated with coliphage concentrations, but not fecal indicator bacteria levels suggesting different persistence trends in Great Lake waters between indicator types (bacteria versus virus). Finally, implications for coliphage water quality management and future research directions are discussed.

Statistical Analysis of Bathing Water Quality in Puglia Region (Italy)

Geostatistic analysis was applied to the dataset from multi-year monitoring, in the Apulian marine-coastal zone (Mediterranean Sea, Italy), on the presence and abundance of intestinal Enterococci and Escherichia coli, microbiological indicators of faecal contamination at the sea. The same faecal contamination can be considered as the main cause of pollution phenomenon under current Italian and European regulations for the bathing waters (Italian Government Decree 116/2008, European Directive 2006/7/CE). The main objective of the study is to verify, taking into the account the anthropic pressures acting on the coastal zone, the efficiency of the Apulian regional monitoring plan currently in force for the assessment of bathing waters quality, with a view to a hypothetical reduction of sample collection points.

Coliphages and Gastrointestinal Illness in Recreational Waters: Pooled Analysis of Six Coastal Beach Cohorts

BACKGROUND

Coliphages have been proposed as indicators of fecal contamination in recreational waters because they better mimic the persistence of pathogenic viruses in the environment and wastewater treatment than fecal indicator bacteria. We estimated the association between coliphages and gastrointestinal illness and compared it with the association with culturable enterococci.

METHODS

We pooled data from six prospective cohort studies that enrolled coastal beachgoers in California, Alabama, and Rhode Island. Water samples were collected and gastrointestinal illness within 10 days of the beach visit was recorded. Samples were tested for enterococci and male-specific and somatic coliphages. We estimated cumulative incidence ratios (CIR) for the association between swimming in water with detectable coliphage and gastrointestinal illness when human fecal pollution was likely present, not likely present, and under all conditions combined. The reference group was unexposed swimmers. We defined continuous and threshold-based exposures (coliphage present/absent, enterococci >35 vs. ≤35 CFU/100 ml).

RESULTS

Under all conditions combined, there was no association between gastrointestinal illness and swimming in water with detectable coliphage or enterococci. When human fecal pollution was likely present, coliphage and enterococci were associated with increased gastrointestinal illness, and there was an association between male-specific coliphage level and illness that was somewhat stronger than the association between enterococci and illness. There were no substantial differences between male-specific and somatic coliphage.

CONCLUSIONS

Somatic coliphage and enterococci had similar associations with gastrointestinal illness; there was some evidence that male-specific coliphage had a stronger association with illness than enterococci in marine waters with human fecal contamination.

The application of bacteriophages as novel indicators of viral pathogens in wastewater treatment systems

Many wastewater treatment technologies have been shown to remove bacterial pathogens more effectively than viral pathogens and, in aquatic environments, levels of traditional faecal indicator bacteria (FIB) do not appear to correlate consistently with levels of human viral pathogens. There is, therefore, a need for novel viral indicators of faecal pollution and surrogates of viral pathogens, especially given the increasing importance of indirect and direct wastewater reuse. Potential candidates include bacteriophages (phages) and the study described here sought to elucidate the relationship between three groups of phages (somatic coliphages (SOMPH), F-RNA coliphages (F-RNAPH) and human-specific phages infecting B. fragilis (Bf124PH) - enumeration using double layer agar technique) and viral pathogens (human adenovirus (HuAdV) and norovirus (NoV) - enumeration using molecular methods) through full-scale municipal wastewater treatment processes. FIB (faecal coliforms (FC) and intestinal enterococci (ENT) - enumeration using membrane filtration) were also monitored. Samples were collected every fortnight, during a twelve-month period, at each stage of four full-scale wastewater treatment plants (WWTP) in southern England (two activated sludge (AS) and two trickling filter (TF) plants) (n = 360 samples). FIB and SOMPH were consistently found in all samples tested, whereas F-RNAPH, Bf124PH and HuAdV were less frequently detected, especially following AS treatment. The detection rate of NoV was low and consequently discussion of this group of viruses is limited. Concentrations of SOMPH and FIB were statistically higher (p value < 0.05) than concentrations of F-RNAPH, Bf124PH and HuAdV in raw wastewater. FIB were more effectively removed than phages in both systems. Removal rates of HuAdV were similar to those of phages at the secondary treatment stage of both systems. In TF systems, HuAdV were removed at the same rate as F-RNAPH, but at lower rates than SOMPH and Bf124PH. The findings suggest that phages (in particular SOMPH) are better indicators of the fate of viral pathogens in WWTP than existing FIB and that these organisms may have a useful role to play in future sanitation safety planning.

Estimating the probability of illness due to swimming in recreational water with a mixture of human- and gull-associated microbial source tracking markers

Beaches often receive fecal contamination from more than one source. Human sources include untreated sewage as well as treated wastewater effluent, and animal sources include wildlife such as gulls. Different contamination sources are expected to pose different health risks to swimmers. Genetic microbial source tracking (MST) markers can be used to detect bacteria that are associated with different animal sources, but the health risks associated with a mixture of MST markers are unknown. This study presents a method for predicting these health risks, using human- and gull-associated markers as an example. Quantitative Microbial Risk Assessment (QMRA) is conducted with MST markers as indicators. We find that risks associated with exposure to a specific concentration of a human-associated MST marker (HF) are greater if the HF source is untreated sewage rather than treated wastewater effluent. We also provide a risk-based threshold of HF from untreated sewage at a beach, to stay below a predicted illness risk of 3 per 100 swimmers, that is a function of gull-associated MST marker (CAT) concentration.

Incidence of gastrointestinal illness following wet weather recreational exposures: Harmonization of quantitative microbial risk assessment with an epidemiologic investigation of surfers

We modeled the risk of gastrointestinal (GI) illness associated with recreational exposures to marine water following storm events in San Diego County, California. We estimated GI illness risks via quantitative microbial risk assessment (QMRA) techniques by consolidating site specific pathogen monitoring data of stormwater, site specific dilution estimates, literature-based water ingestion data, and literature based pathogen dose-response and morbidity information. Our water quality results indicated that human sources of contamination contribute viral and bacterial pathogens to streams draining an urban watershed during wet weather that then enter the ocean and affect nearshore water quality. We evaluated a series of approaches to account for uncertainty in the norovirus dose-response model selection and compared our model results to those from a concurrently conducted epidemiological study that provided empirical estimates for illness risk following ocean exposure. The preferred norovirus dose-response approach yielded median risk estimates for water recreation-associated illness (15 GI illnesses per 1000 recreation events) that closely matched the reported epidemiological results (12 excess GI illnesses per 1000 wet weather recreation events). The results are consistent with norovirus, or other pathogens associated with norovirus, as an important cause of gastrointestinal illness among surfers in this setting. This study demonstrates the applicability of QMRA for recreational water risk estimation, even under wet weather conditions and describes a process that might be useful in developing site-specific water quality criteria in this and other locations.

High level bacterial contamination of secondary school students' mobile phones

INTRODUCTION

While contamination of mobile phones in the hospital has been found to be common in several studies, little information about bacterial abundance on phones used in the community is available. Our aim was to quantitatively determine the bacterial contamination of secondary school students' mobile phones.

METHODS

Altogether 27 mobile phones were studied. The contact plate method and microbial identification using MALDI-TOF mass spectrometer were used for culture studies. Quantitative PCR reaction for detection of universal 16S rRNA, Enterococcus faecalis 16S rRNA and Escherichia coli allantoin permease were performed, and the presence of tetracycline (tetA, tetB, tetM), erythromycin (ermB) and sulphonamide (sul1) resistance genes was assessed.

RESULTS

We found a high median bacterial count on secondary school students' mobile phones (10.5 CFU/cm²) and a median of 17,032 bacterial 16S rRNA gene copies per phone. Potentially pathogenic microbes (Staphylococcus aureus, Acinetobacter spp., Pseudomonas spp., Bacillus cereus and Neisseria flavescens) were found among dominant microbes more often on phones with higher percentage of E. faecalis in total bacterial 16S rRNA. No differences in contamination level or dominating bacterial species between phone owner's gender and between phone types (touch screen/keypad) were found. No antibiotic resistance genes were detected on mobile phone surfaces.

CONCLUSION

Quantitative study methods revealed high level bacterial contamination of secondary school students' mobile phones.

Occurrence of norovirus in raw sewage - A systematic literature review and meta-analysis

Human noroviruses (NoV) are a leading cause of recreational waterborne illnesses and responsible for the majority of viral-associated gastrointestinal illnesses nationwide. We conducted a systematic literature review of published peer-reviewed publications to identify NoV density data in wastewater influent, and provided an approach for developing pathogen density distributions, using the NoV data. Literature review inclusion criteria included scope, study quality, and data availability. A non-parametric bootstrap statistical model was used to estimate the NoV distribution in wastewater influent. The approach used accounts for heterogeneity in study-specific distribution curves, sampling locations, and sampling season and provides a comprehensive representation of the data. Study results illustrate that pooling all of the available NoV data together in a meta-analysis provides a more comprehensive understanding of the technical literature than what could be appreciated from individual studies. The studies included in this analysis indicate a high density of NoV in wastewater influent (overall mean = 4.6 log₁₀ genome copies (GC)/liter (L)), with a higher density of NoV genogroup (G) II (overall mean = 4.9 log₁₀ GC/L) than for GI (overall mean = 4.4 log₁₀ GC/L for GI). The bootstrapping approach was also used to account for differences in seasonal and geographical occurrences of NoV GI and GII. The methods presented are reproducible and can be used to develop QMRA-ready density distributions for other viral pathogens in wastewater influent, effluent, and ambient waters. To our knowledge, our results are the first to quantitatively characterize seasonal and geographic differences, which could be particularly useful for future risk assessments.

Monitoring bacterial indicators of water quality in a tidally influenced delta: A Sisyphean pursuit

The Sacramento-San Joaquin Delta Estuary (Delta) is the confluence of two major watersheds draining the Western Sierra Nevada mountains into the Central Valley of California, ultimately terminating into San Francisco Bay. We sampled 88 sites once a month for two years (2006-2008) over 87 separate sampling events for a total of 1740 samples. Water samples were analyzed for fecal indicator bacteria (Escherichia coli, enterococci and fecal coliforms), and 53 other physiochemical, land use, and environmental characteristics. The purpose of the study was to create a baseline of microbial water quality in the Delta and to identify various factors (climatic, land use, tidal, etc.) that were associated with elevated concentrations of indicator bacteria. Fecal indicator bacteria generally had weak to modest relationships to environmental conditions; the strength and direction of which varied for each microbial indicator, drainage region, and across seasons. Measured and unmeasured, site-specific effects accounted for large portions of variance in model predictions (ρ=0.086 to 0.255), indicating that spatial autocorrelation was a major component of water quality outcomes. The effects of tidal cycling and lack of connectivity between waterways and surrounding landscapes likely contributed to the lack of association between local land uses and microbial outcomes, though weak associations may also be indicative of mismatched spatiotemporal scales. The complex nature of this system necessitates continued monitoring and regular updates to statistical models designed to predict microbial water quality.

Decay of Coliphages in Sewage-Contaminated Freshwater: Uncertainty and Seasonal Effects

Understanding the fate of enteric viruses in water is vital for protection of water quality. However, the decay of enteric viruses is not well characterized, and its uncertainty has not been examined yet. In this study, the decay of coliphages, an indicator for enteric viruses, was investigated in situ under both sunlit and shaded conditions as well as in summer and winter. The decay rates of coliphages and their uncertainties were analyzed using a Bayesian approach. The results from the summer experiments revealed that the decay rates of somatic coliphages were significantly higher in sunlight (1.29 ± 0.06 day^-1) than in shade (0.96 ± 0.04 day^-1), but the decay rates of male-specific (F+) coliphages were not significantly different between sunlight (1.09 ± 0.09 day^-1) and shaded treatments (1.11 ± 0.08 day^-1). The decay rates of both F+ coliphages (0.25 ± 0.02 day^-1) and somatic coliphages (0.12 ± 0.01 day^-1) in winter were considerably lower than those in summer. Temperature and chlorophyll a (chla) concentration varied significantly (p < 0.001) between the two seasons, suggesting that these parameters might be important contributors to the seasonal variation of coliphage decay. Additionally, the Bayesian approach provided full distributions of decay rates and reduced the uncertainty, offering useful information for comparing decay rates under different conditions.