Fecal Indicator Concentrations Research Articles

Health Risks to Communities and Athletes Associated with Swimming, Wading, and Sailing in Water Bodies of Brazil’s Guanabara Bay Basin

Guanabara Bay has been known to be polluted with trash and sewage from the surrounding areas, but health risks from recreational contact with water in the basin have not been well characterized. In this paper, fecal indicator bacteria (FIB) monitoring data are used to predict risks in three different exposure scenarios: (1) bathing in freshwater rivers that discharge into Guanabara Bay, (2) wading in these freshwater rivers, and (3) sailing in Guanabara Bay. Concentrations of indicator bacteria in river samples were measured directly, and concentrations of indicator bacteria in bay samples were sourced from publicly available government data sets. Ratios between pathogens and fecal indicator concentrations were used to estimate risks for five selected pathogens based on the indicator concentrations. The median risk of disease estimated from E. coli indicator concentrations was 1.0, 9.9 × 10−1 and 8.2 × 10−4 for the swimming, wading, and sailing exposure pathways, respectively. Risks estimates based on concentrations of the enterococci indicator bacteria in the sailing exposure scenario were comparable, at 3.4 × 10−4. The sum of total risk estimated from the five selected pathogens was 5.9 × 10−1, 3.6 × 10−1, and 1.0 × 10−3 for the swimming, wading, and sailing exposure pathways, respectively. Estimated risks of swimming and wading in the rivers far exceeded risks associated with U.S. recreational contact standards, while estimated risks for sailing in the bay were well below these risk guidelines. The 95th percentile of the sailing risk was estimated to exceed the U.S. recreational contact risk level. This paper exemplifies an approach to conducting quantitative microbial risk assessments when only fecal indicator bacteria data are available. Context-specific data on the relevant exposure routes, exposure frequency, and site-specific indicator: pathogen ratios were lacking, which ultimately led to uncertainty in the model. This study is intended to provide a framework for estimating GI risk based on fecal indicator concentrations while acknowledging that the substantial variation in indicator:pathogen ratios make the results of such efforts uncertain.

Use of Somatic Coliphages in Biosensoring of Hygiene Safety of Recycled Wastewater

Outflows from secondary stages of conventional mechanical-biological wastewater treatment plants (WWTPs) still contain significant concentrations of faecal pollution indicators suggesting the potential presence of pathogenic organisms. The decrease in the concentration of somatic coliphages and bacterial indicators of faecal pollution during the technological stages (coagulation, sand filtration, membrane ultrafiltration, sorption on granular activated carbon, disinfection, accumulation) of a semi-operational plant designed for multi-stage tertiary treatment or rather recycling of treated wastewater was monitored and discussed. During the tertiary treatment, faecal bacteria indicators were better removed than somatic coliphages, hence the inclusion of somatic indicators among faecal pollution indicators in water quality control for reuse is entirely appropriate. Subsequent tertiary treatment, including disinfection, is essential for safe reuse of treated water.

Multiple fluorescence approaches to identify rapid changes in microbial indicators at karst springs

Karst springs are globally important for drinking water supply but are often also exceptionally vulnerable to contamination. Such springs usually exhibit strong variation in microbial water quality in sharp response to rainfall events, thus, posing a health hazard to consumers of water supplied from these sources. The rapid detection of such changes is extremely important as well as being able to establish a link to the sources of such pollution, so that appropriate measures can be taken both in terms of immediate protection of human health and the management of karst aquifers. In this study, a fluorescence-based multi-parameter approach was trialed in order to evaluate which methods can be used to monitor rainfall-induced rapid changes in microbial water quality at karst springs, as well as determine whether such changes can be linked to sources of human effluent contamination. The results from three monitoring periods at two karst springs revealed marked responses to rainfall events for all of the microbial parameters measured. Total cell count (TCC) measurements using flow cytometry (FCM) showed very strong positive correlations with the more conventionally monitored faecal indicator bacteria (FIB) and total coliforms (TC), indicating that such a fluorescence-based and cultivation-independent technique can be very useful to indicate rapid changes in microbial water quality at karst springs. Furthermore, very strong positive correlations were also found between tryptophan-like fluorescence (TLF) measurements and concentrations of all monitored microbial parameters, again demonstrating that such a fluorescence-based approach can also be useful for detecting rapid changes in concentrations of traditional faecal indicators. Interestingly, it was found that fluorescent whitening compounds (FWCs) signals do not necessarily follow temporal variations of microbial indicators. However, the frequency of detection of positive FWCs signals may still reveal useful information about the overall magnitude of human wastewater effluent impacts on karst aquifer systems.

Wastewater surveillance of SARS-CoV-2 in dormitories as a part of comprehensive university campus COVID-19 monitoring

Wastewater-based epidemiology is an effective tool for monitoring infectious disease spread or illicit drug use within communities. At the Ohio State University, we conducted a SARS-CoV-2 wastewater surveillance program in the 2020–2021 academic year and compared results with the university-required weekly COVID-19 saliva testing to monitor COVID-19 infection prevalence in the on-campus residential communities. The objectives of the study were to rapidly track trends in the wastewater SARS-CoV-2 gene concentrations, analyze the relationship between case numbers and wastewater signals when adjusted using human fecal viral indicator concentrations (PMMoV, crAssphage) in wastewater, and investigate the relationship of the SARS-CoV-2 gene concentrations with wastewater parameters. SARS-CoV-2 nucleocapsid and envelope (N1, N2, and E) gene concentrations, determined with reverse transcription droplet digital PCR, were used to track SARS-CoV-2 viral loads in dormitory wastewater once a week at 6 sampling sites across the campus during the fall semester in 2020. During the following spring semester, research was focused on SARS-CoV2 N2 gene concentrations at 5 sites sampled twice a week. Spearman correlations both with and without adjusting using human fecal viral indicators showed a significant correlation (p < 0.05) between human COVID-19 positive case counts and wastewater SARS-CoV-2 gene concentrations. Spearman correlations showed significant relationships between N1 gene concentrations and both TSS and turbidity, and between E gene concentrations and both pH and turbidity. These results suggest that wastewater signal increases with the census of infected individuals, in which the majority are asymptomatic, with a statistically significant (p-value <0.05) temporal correlation. The study design can be utilized as a platform for rapid trend tracking of SARS-CoV-2 variants and other diseases circulating in various communities.

Surveillance of RNase P, PMMoV, and CrAssphage in wastewater as indicators of human fecal concentration across urban sewer neighborhoods, Kentucky

AbstractWastewater surveillance has been widely used as a supplemental method to track the community infection levels of severe acute respiratory syndrome coronavirus 2. A gap exists in standardized reporting for fecal indicator concentrations, which can be used to calibrate the primary outcome concentrations from wastewater monitoring for use in epidemiological models. To address this, measurements of fecal indicator concentration among wastewater samples collected from sewers and treatment centers in four counties of Kentucky (N = 650) were examined. Results from the untransformed wastewater data over 4 months of sampling indicated that the fecal indicator concentration of human ribonuclease P (RNase P) ranged from 5.1 × 101 to 1.15 × 106 copies/ml, pepper mild mottle virus (PMMoV) ranged from 7.23 × 103 to 3.53 × 107 copies/ml, and cross-assembly phage (CrAssphage) ranged from 9.69 × 103 to 1.85 × 108 copies/ml. The results showed both regional and temporal variability. If fecal indicators are used as normalization factors, knowing the daily sewer system flow of the sample location may matter more than rainfall. RNase P, while it may be suitable as an internal amplification and sample adequacy control, has less utility than PMMoV and CrAssphage as a fecal indicator in wastewater samples when working at different sizes of catchment area. The choice of fecal indicator will impact the results of surveillance studies using this indicator to represent fecal load. Our results contribute broadly to an applicable standard normalization factor and assist in interpreting wastewater data in epidemiological modeling and monitoring.

Elucidation of fecal inputs into the River Tagus catchment (Portugal) using source-specific mitochondrial DNA, HAdV, and phage markers

Determining the source of fecal contamination in a water body is important for the application of appropriate remediation measures. However, it has been suggested in the extant literature that this can best be achieved using a ‘toolbox’ of molecular- and culture-based methods. In response, this study deployed three indicators (Escherichia coli (EC), intestinal enterococci (IE) and somatic coliphages (SC)), one culture-dependent human marker (Bacteroides (GB-124) bacteriophage) and five culture-independent markers (human adenovirus (HAdV), human (HMMit), cattle (CWMit), pig (PGMit) and poultry (PLMit) mitochondrial DNA markers (mtDNA)) within the River Tagus catchment (n = 105). Water samples were collected monthly over a 13-month sampling campaign at four sites (impacted by significant specific human and non-human inputs and influenced by differing degrees of marine and freshwater mixing) to determine the dominant fecal inputs and assess geographical, temporal, and meteorological (precipitation, UV, temperature) fluctuations. Our results revealed that all sampling sites were not only highly impacted by fecal contamination but that this contamination originated from human and from a range of agricultural animal sources. HMMit was present in a higher percentage (83%) and concentration (4.20 log GC/100 mL) than HAdV (32%, 2.23 log GC/100 mL) and GB-124 bacteriophage with the latter being detected once. Animal mtDNA markers were detected, with CWMit found in 73% of samples with mean concentration of 3.74 log GC/100 mL. Correlation was found between concentrations of fecal indicators (EC, IE and SC), CWMit and season. Levels of CWMit were found to be related to physico-chemical parameters, such as temperature and UV radiation, possibly as a result of the increasing presence of livestock outside in warmer months. This study provides the first evaluation of such a source-associated ‘toolbox’ for monitoring surface water in Portugal, and the conclusions may inform future implementation of surveillance and remediation strategies for improving water quality.

Total coliform and Escherichia coli in microplastic biofilms grown in wastewater and inactivation by peracetic acid.

Microplastics (MP) have been proposed as a vector for pathogenic microorganisms in the freshwater environment. The objectives of this study were (a) to compare the fecal indicator growth in biofilms on MP and material control microparticles incubated in different wastewater fractions and (b) to compare MP biofilm, natural microparticle biofilm, and planktonic cell susceptibility to disinfection by peracetic acid (PAA). Biofilms were grown on high-density polyethylene, low-density polyethylene, polypropylene MP, or wood chips (as a material control) and incubated in either wastewater influent or pre-disinfection secondary effluent. Reactors were disinfected with PAA, biofilms were dislodged, and total coliform and Escherichia coli were cultivated. Fecal indicators were quantifiable in both MP and wood biofilms incubated in the wastewater influent but only on the wood biofilms incubated in secondary wastewater effluent. More total coliform grew in the wood biofilms than MP biofilms, and the biofilms grown on MP and woodchips were more resistant to disinfection than planktonic bacteria. Thus, it may be possible to refer to the disinfection literature for fecal indicators in biofilm on other particles to predict behavior on MP. Treatments that remove particles in general would help reduce the potential for fecal indicator bypass of disinfection. PRACTITIONER POINTS: MP biofilm had lower concentrations of fecal indicators than wood biofilm Biofilm on MP was not more resistant to disinfection than wood biofilm Biofilms, regardless of substrate, were more resistant to disinfection than planktonic organisms.

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.

Quantitative Microbial Risk Assessment as support for bathing waters profiling

Profiling bathing waters supported by Quantitative Microbial Risk Assessment (QMRA) is key to the WHO's recommendations for the 2020/2021 revision of the European Bathing Water Directive. We developed an area-specific QMRA model on four pathogens, using fecal indicator concentrations (E. coli, enterococci) for calculating pathogen loads. The predominance of illness was found to be attributable to Human Adenovirus, followed by Salmonella, Vibrio, and Norovirus. Overall, the cumulative illness risk showed a median of around 1 case/10000 exposures. The risk estimates were strongly influenced by the indicators that were used, suggesting the need for a more detailed investigation of the different sources of fecal contamination. Area-specific threshold values for fecal indicators were estimated on a risk-basis by modelling the cumulative risk against E. coli and enterococci concentrations. To improve bathing waters assessment, we suggest considering source apportionment, locally estimating of pathogen/indicator ratios, and calculating site-specific indicators thresholds based on risk assessment.

Effect of the time scale on the uncertainty of geometric mean concentrations of fecal indicators in creek under baseflow conditions

Geometric mean concentrations of fecal indicator bacteria E. coli and enterococci are commonly used to evaluate the microbial quality of irrigation, recreation, and other types of waters, as well in watershed-scale microbial water quality modeling. It is not known how the uncertainty of those geometric mean concentrations depends on the time period between sampling. We analyzed data collected under baseflow conditions from three years of weekly and several daily sampling campaigns at Conococheague Creek in Pennsylvania. Standard deviations of logarithms of geometric mean concentrations were computed over weeks, months, and seasons. The increase in standard deviations from weekly to seasonal time scale was on average about 0.1 and 0.2 for log(E. coli) and log(enterococci), respectively, and in most cases was statistically significant. This may need to be accounted for when evaluating the uncertainty of measurements for modeling purposes and in risk assessment of microbial water quality.

Setback distance impacts on transport and antibiotic resistance phenotypes of fecal indicators

AbstractAlthough the land application of livestock manure has numerous agronomic benefits, runoff from manured fields can degrade water quality. Setbacks instruct a minimum distance be maintained between manure application and surface waters. They are commonly used to manage nutrient contamination of surface waters; however, their utility for reducing microbial inputs remains unclear. Here we evaluated the efficacy of five setback distances in no‐till wheat (Triticum aestivum L.) residue plots for reducing runoff fecal indicator concentrations from swine manure‐amended fields. Also, since there is increasing interest in the use of water quality indicators to monitor antibiotic resistance in environmental systems, Escherichia coli and Enterococcus isolates were collected, and evaluated for resistance to 12 antibiotics. Seven of the 12 antibiotics evaluated in this study are critically important to human health and another four of the antibiotics evaluated are highly important to human health, according to World Health Organization (WHO) guidelines. Significant differences existed in amounts of indicators from pre‐ and post‐manure application time points; however, no significant differences were observed for any of the five setback distances measured (range 4.9–23.2 m). Antibiotic‐resistant E. coli and Enterococcus were isolated from pre‐ and post‐application runoff, indicating presence of antibiotic‐resistant fecal indicators in both manured and in non‐manured soils, although the source manure had a higher percentage of isolates displaying resistance. It remains difficult to provide recommendations for concurrent reduction of nutrient and microbial contaminants.

Prediction of fecal indicator organism concentrations in rivers: the shifting role of environmental factors under varying flow conditions

BackgroundFecal indicator organisms such as Escherichia coli, enterococci, and coliphages are important to assess, monitor, and predict microbial water quality in natural freshwater ecosystems. To improve predictive modelling of fecal indicators in surface waters, it is vital to assess the influence of autochthonous and allochthonous environmental factors on microbial water quality in riverine systems. To better understand how environmental conditions influence the fate of fecal indicators under varying weather conditions, the interdependencies of environmental parameters and concentrations of E. coli, intestinal enterococci, and somatic coliphages were studied at two rivers (Rhine and Moselle in Rhineland-Palatinate, Germany) over a period of 2 years that exhibited contrasting hydrological conditions. Both riverine sampling sites were subject to similar meteorological conditions based on spatial proximity, but differed in hydrodynamics and hydrochemistry, thus providing further insight into the role of river-specific determinants on fecal indicator concentrations. Furthermore, a Bayesian multiple linear regression approach that complies with the European Bathing Water Directive was applied to both rivers’ datasets to test model transferability and the validity of microbial water quality predictions in riverine systems under varying flow regimes.ResultsAccording to multivariate statistical analyses, rainfall events and high water discharge favored the input and dissemination of fecal indicators in both rivers. As expected, concentrations declined with rising global solar irradiance, water temperature, and pH. While variations in coliphage concentrations were predominantly driven by hydro-meteorological factors, bacterial indicator concentrations were strongly influenced by autochthonous biotic factors related to primary production. This was more pronounced under low flow conditions accompanied by strong phytoplankton blooms. Strong seasonal variations pointed towards bacterial indicator losses due to grazing activities. The Bayesian linear regression approach provided appropriate water quality predictions at the Rhine sampling site based on discharge, global solar irradiance, and rainfall as fecal indicator distributions were predominantly driven by hydro-meteorological factors.ConclusionsAssessment of microbial water quality predictions implied that rivers characterized by strong hydrodynamics qualify for multiple linear regression models using readily measurable hydro-meteorological parameters. In rivers where trophic interactions exceed hydrodynamic influences, such as the Moselle, viral indicators may pose a more reliable response variable in statistical models.

A review on microbial contaminants in stormwater runoff and outfalls: Potential health risks and mitigation strategies.

Demands on global water supplies are increasing in response to the need to provide more food, water, and energy for a rapidly growing population. These water stressors are exacerbated by climate change, as well as the growth and urbanisation of industry and commerce. Consequently, urban water authorities around the globe are exploring alternative water sources to meet ever-increasing demands. These alternative sources are primarily treated sewage, stormwater, and groundwater. Stormwater including roof-harvested rainwater has been considered as an alternative water source for both potable and non-potable uses. One of the most significant issues concerning alternative water reuse is the public health risk associated with chemical and microbial contaminants. Several studies to date have quantified fecal indicators and pathogens in stormwater. Microbial source tracking (MST) approaches have also been used to determine the sources of fecal contamination in stormwater and receiving waters. This review paper summarizes occurrence and concentrations of fecal indicators, pathogens, and MST marker genes in urban stormwater. A section of the review highlights the removal of fecal indicators and pathogens through water sensitive urban design (WSUD) or Best Management Practices (BMPs). We also discuss approaches for assessing and mitigating health risks associated with stormwater, including a summary of existing quantitative microbial risk assessment (QMRA) models for potable and non-potable reuse of stormwater. Finally, the most critical research gaps are identified for formulating risk management strategies.

A constructed wetland for treatment of an impacted waterway and the influence of native waterfowl on its perceived effectiveness

A constructed, variable-flow treatment wetland was evaluated for its ability to reduce microbial loads from the Banklick Creek, an impacted recreational waterway in Northern Kentucky. For this study, levels of traditional (Escherichia coli and enterococci measured by culture and molecular techniques) and alternative fecal indicators (infectious somatic and F+ coliphage, Clostridium spp. and Clostridium perfringens by culture), potential pathogens (molecular signal of Campylobacter spp.) as well as various microbial source tracking (MST) markers (human fecal marker HF183 and avian fecal marker GFD) were monitored during the summer and early fall through five treatment stages within the Banklick Creek Wetland. No difference in concentrations of traditional or alternative fecal indicators were observed in any of the sites monitored. Microbial source tracking markers were employed to identify sources of fecal contamination within the wetland. Human marker HF183 concentrations at beginning stages of treatment were found to be significantly higher (P value range: 0.0016–0.0003) than levels at later stages. Conversely, at later stages of treatment where frequent bird activity was observed, Campylobacter and avian marker (GFD) signals were detected at significantly higher frequencies (P value range: 0.024 to <0.0001), and both signals were strongly correlated (P = 0.0001). Our study suggests constructed wetlands are an effective means for removal of microbial contamination in ambient waters, but reliance on general fecal indicators is not ideal for determining system efficacy or assessing appropriate remediation efforts.

Within-day variability in microbial concentrations at a UK designated bathing water: Implications for regulatory monitoring and the application of predictive modelling based on historical compliance data

Prediction of bathing water quality is recommended by the World Health Organization (WHO), the European Union (EU) and the United States Environmental Protection Agency (USEPA) and is an established element in bathing water management designed to protect public health. Most commonly, historical regulatory compliance data are used for model calibration and provide the dependent variable for modelling. Independent (or predictor) variables (e.g. rainfall, river flow and received irradiance) measured over some antecedent period are used to deliver prediction of the faecal indicator concentration measured on the day of the regulatory sample collection. The implied linked assumptions of this approach are, therefore, that; (i) the independent variables accurately predict the bathing-day water quality; which is (ii) accurately characterized by the single regulatory sample. Assumption (ii) will not be the case where significant within-day variability in water quality is evident. This study built a detailed record of water quality change through 60 days at a UK coastal bathing water in 2011 using half-hourly samples each subjected to triplicate filtration designed to enhance enumeration precision. On average, the mean daily variation in FIO concentrations exceeded 1 log10 order, with the largest daily variations exceeding 2 log10 orders. Significant diurnality was observed at this bathing water, which would determine its EU Directive compliance category if the regulatory samples were collected at the same time each day. A sampling programme of this intensity has not been reported elsewhere to date and, if this pattern is proven to be characteristic of other bathing waters world-wide, it has significance for: (a) the design of regulatory sampling programmes; (b) the use of historical data to assess compliance, which often comprises a single sample taken at the compliance point on a regular, often weekly, basis; and (c) the use of regulatory compliance data to build predictive models of water quality.

Disease epidemiology and prevalence of neurological manifestations in neuronopathic Gaucher disease: Comprehensive review of the literature

A constructed, variable-flow treatment wetland was evaluated for its ability to reduce microbial loads from the Banklick Creek, an impacted recreational waterway in Northern Kentucky. For this study, levels of traditional (Escherichia coli and enterococci measured by culture and molecular techniques) and alternative fecal indicators (infectious somatic and F+ coliphage, Clostridium spp. and Clostridium perfringens by culture), potential pathogens (molecular signal of Campylobacter spp.) as well as various microbial source tracking (MST) markers (human fecal marker HF183 and avian fecal marker GFD) were monitored during the summer and early fall through five treatment stages within the Banklick Creek Wetland. No difference in concentrations of traditional or alternative fecal indicators were observed in any of the sites monitored. Microbial source tracking markers were employed to identify sources of fecal contamination within the wetland. Human marker HF183 concentrations at beginning stages of treatment were found to be significantly higher (P value range: 0.0016–0.0003) than levels at later stages. Conversely, at later stages of treatment where frequent bird activity was observed, Campylobacter and avian marker (GFD) signals were detected at significantly higher frequencies (P value range: 0.024 to <0.0001), and both signals were strongly correlated (P = 0.0001). Our study suggests constructed wetlands are an effective means for removal of microbial contamination in ambient waters, but reliance on general fecal indicators is not ideal for determining system efficacy or assessing appropriate remediation efforts.

Limited influence of primary treated sewage waters on bacterial abundance, production and community composition in coastal seawaters

The response of bacteria in terms of abundance, production and community structure to changes induced by the discharge of primary treated sewage waters was investigated combining microbiological, chemical and molecular tools. The primary treatment did not affect substantially the bacterial community structure in wastewaters and did not reduce the concentrations of fecal indicators. The spatial distribution of the sewage plume was governed by vertical stratification and currents. Bacterial abundance and production in the sea receiving waste waters depended predominantly on environmental conditions. In the waters with the highest concentration of fecal pollution indicators the bacterial community was characterized by allochthonous bacteria belonging to Epsilonproteobacteria, Firmicutes, Gammaproteobacteria and Bacteroidetes. The latter two taxa were also present in unpolluted waters but had a different structure, typical for oligotrophic environments. Although the impact of primary treated sewage waters was limited, a sanitary risk persisted due to the relevant presence of potentially pathogenic bacteria.

Quantitative Microbial Risk Assessment for Spray Irrigation of Dairy Manure Based on an Empirical Fate and Transport Model.

Background:Spray irrigation for land-applying livestock manure is increasing in the United States as farms become larger and economies of scale make manure irrigation affordable. Human health risks from exposure to zoonotic pathogens aerosolized during manure irrigation are not well understood.Objectives:We aimed to a) estimate human health risks due to aerosolized zoonotic pathogens downwind of spray-irrigated dairy manure; and b) determine which factors (e.g., distance, weather conditions) have the greatest influence on risk estimates.Methods:We sampled downwind air concentrations of manure-borne fecal indicators and zoonotic pathogens during 21 full-scale dairy manure irrigation events at three farms. We fit these data to hierarchical empirical models and used model outputs in a quantitative microbial risk assessment (QMRA) to estimate risk [probability of acute gastrointestinal illness (AGI)] for individuals exposed to spray-irrigated dairy manure containing Campylobacter jejuni, enterohemorrhagic Escherichia coli (EHEC), or Salmonella spp.Results:Median risk estimates from Monte Carlo simulations ranged from to and decreased with distance from the source. Risk estimates for Salmonella or EHEC-related AGI were most sensitive to the assumed level of pathogen prevalence in dairy manure, while risk estimates for C. jejuni were not sensitive to any single variable. Airborne microbe concentrations were negatively associated with distance and positively associated with wind speed, both of which were retained in models as a significant predictor more often than relative humidity, solar irradiation, or temperature.Conclusions:Our model-based estimates suggest that reducing pathogen prevalence and concentration in source manure would reduce the risk of AGI from exposure to manure irrigation, and that increasing the distance from irrigated manure (i.e., setbacks) and limiting irrigation to times of low wind speed may also reduce risk. https://doi.org/10.1289/EHP283

Temporal variations analyses and predictive modeling of microbiological seawater quality

Bathing water quality is a major public health issue, especially for tourism-oriented regions. Currently used methods within EU allow at least a 2.2 day period for obtaining the analytical results, making outdated the information forwarded to the public. Obtained results and beach assessment are influenced by the temporal and spatial characteristics of sample collection, and numerous environmental parameters, as well as by differences of official water standards. This paper examines the temporal variation of microbiological parameters during the day, as well as the influence of the sampling hour, on decision processes in the management of the beach. Apart from the fecal indicators stipulated by the EU Bathing Water Directive (E. coli and enterococci), additional fecal (C. perfringens) and non-fecal (S. aureus and P. aeriginosa) parameters were analyzed. Moreover, the effects of applying different evaluation criteria (national, EU and U.S. EPA) to beach ranking were studied, and the most common reasons for exceeding water-quality standards were investigated. In order to upgrade routine monitoring, a predictive statistical model was developed.The highest concentrations of fecal indicators were recorded early in the morning (6 AM) due to the lack of solar radiation during the night period. When compared to enterococci, E. coli criteria appears to be more stringent for the detection of fecal pollution. In comparison to EU and U.S. EPA criteria, Croatian national evaluation criteria provide stricter public health standards. Solar radiation and precipitation were the predominant environmental parameters affecting beach water quality, and these parameters were included in the predictive model setup. Predictive models revealed great potential for the monitoring of recreational water bodies, and with further development can become a useful tool for the improvement of public health protection.

Temporal Evolution of the Microbiological Conditions of a Sicilian Area Designed for Aquaculture (Castellammare Gulf, Southern Tyrrhenian Sea)

Microbiological controls of coastal seawaters are a common practice to verify their safety for human recreational and productive uses. The aim of the present study is to describe the microbiological conditions of the Castellammare Gulf (Trapani, Sicily), an area traditionally used for aquaculture purposes. Particularly, the results obtained from three surveys (1993-1995, 2000-2001 and 2007) are compared in order to depict how the hygienic-sanitary conditions of this marine ecosystem have evolved over time. Attention has been given to the abundance and distribution of the bacterial indicators of faecal pollution (faecal coliforms, enterococci and Salmonella spp.) as well as halophilic vibrios, using the culture methods conventionally indicated by current legislation in force for the sanitary control of waters designed for aquaculture productions. The obtained results shows that the sanitary conditions of seawater samples met the criteria recommended by current legislations for shellfish farming approved areas. The low concentrations of faecal pollution indicators and of halophilic vibrios confirm the general suitability of the Gulf of Castellammare for seafood production. Nevertheless, the detection of low percentages of potentially pathogenic species of halophilic vibrios stresses the importance of extending microbiological controls also to these emerging pathogens.