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Numerous global studies have explored the fate of Coronavirus-2 within wastewater treatment plants. While research has confirmed virus transmission through aerosols generated in these facilities, the effect of different aeration methods on the potential transmission of this virus and other pathogens remains unclear. In this study, we aimed to examine the occurrence of Coronavirus-2 in air samples collected from two wastewater treatment plants employing diffused and surface aeration. Totally, 48 air samples (passive/active) were collected from 1.5, 10, and 50 m distances from both sequencing batch reactor and conventional activated sludge systems. Subsequently, a quantitative microbial risk assessment model was applied to evaluate the risk of Coronavirus-2 infection for staff. Results showed that all samples from the conventional activated sludge, and only 5% of samples from the sequencing batch reactor, were positive for Coronavirus-2 when tested at a 1.5-m distance from the aeration tanks. Quantification results revealed that the concentration of Coronavirus-2 in positive air samples from the CAS system, targeting the RdRp and N genes, varied from 15 to 239 and 15 to 119 genomic copies per liter, respectively. Quantitative microbial risk assessment revealed an annual infection risk of 3.6 × 10–1 (95% CI 1.8 × 10–7–1)/person/year for staff, which was 2–4 times higher than the suggested values by the United States Environmental Protection Agency (10–4/person/year). According to the results of this study, the diffused aeration system can be considered as a safer option due to the very low spread of pathogens. [ABSTRACT FROM AUTHOR]

Small water supply systems (SWSSs) are often more vulnerable to waterborne disease outbreaks. In Japan, many SWSSs operate without regulation under the Waterworks Law, yet there is limited investigation into microbial contamination and the associated health risks. In this study, the microbiological water quality of four SWSSs that utilize mountain streams as water sources and do not install water treatment facilities were monitored for over 2 years. In investigated SWSSs, the mean heterotrophic plate counts were below 350 CFU/mL, and the total bacterial loads (16S rDNA concentration) ranged from 4.71 to 5.35 log10 copies/mL. The results also showed the consistent presence of fecal indicator bacteria (FIB), i.e., Escherichia coli and Clostridium perfringens, suggesting the potential of fecal pollution. E. coli was then utilized as an indicator to assess the health risk posed by E. coli O157:H7 and Campylobacter jejuni. The results indicated that the estimated mean annual risk of infection and disability-adjusted life years (DALYs) exceeded acceptable levels in all SWSSs for the two reference pathogens. To ensure microbial water safety, implementing appropriate water treatment facilities with an estimated mean required reduction of 5–6 log10 was necessary. This study highlighted the potential microbial contamination and health risk level in SWSSs that utilize mountain streams as water sources, even though the water sources were almost not affected by human activities. Furthermore, this study would also be helpful in supporting risk-based water management to ensure a safe water supply in SWSSs. [ABSTRACT FROM AUTHOR]

This study accessed the efficiency and health risks of drinking water from different sources treated by filtration, boiling, chlorination, flocculation, and solar disinfection. The microbial quality of 45 treated water samples from boreholes, wells, and pipe-borne water was analyzed to determine treatment effectiveness and to quantify risk using quantitative microbial risk assessment. The effectiveness of each treatment method was a function of sampling sources (p < 0.05) and location (p < 0.10), chlorination and boiling being the most efficient methods (100%). Shiegella in well water samples treated by filtration and flocculation had the highest daily infection risk of 69.5 × 10−1 and 67.5 × 10−1 pppd. The annual risk of infection from Salmonella, Shigella, and Staphylococcus ranged from 7.8 × 10−1 to 1.00 pppy, exceeding the U.S. EPA annual infection benchmark (≤10−4 pppy). Salmonella, Shigella, and Staphylococcus had the highest risk of illness of 4.50 × 10−1, 3.30 × 10−1, and 9.80 × 10−1, respectively. All disease burden values exceeded the WHO disease burden benchmark (≤10−6 DALYs/pppy), with Staphylococcus and Salmonella contributing the highest disease burden of 4.71 × 10−2 and 2.13 × 10−2, DALYs/pppy. Therefore, boiling and chlorination are the best disinfection methods for the pathogens tested. HIGHLIGHTS Filtration of drinking water with ceramic filters (the most common LHWT method in Bamenda, Cameroon) is the least effective method in removing bacterial contaminants such as Salmonella, Shigella and Staphylococcus.; Boiling and chlorinaIon are the most effective disinfection methods for the pathogens tested.; Filtration, flocculation, and SODIS did not reduce pathogenic concentraIons below risk levels.; Bacteria contaminants in poorly-treated drinking water exceeded the WHO disease burden benchmark.;

Abstract Cholera infection results from the ingestion of water or food contaminated with toxigenic Vibrio cholerae. This study evaluated the occurrence of toxigenic V. cholerae in Asata River, Enugu Metropolis, Nigeria, and estimated V. cholerae infection risks from use of the River water for drinking, domestic and recreational purposes. Vibrio was detected and quantified using membrane filtration technique and thiosulfate–citrate–bile salts–sucrose agar. Isolates were screened by PCR, using specific primers targeting the internal transcribed spacer (its) region between 16 and 23S rRNA and the cholera toxin (ctx) gene. Sequenced 16SrRNA gene amplicons of two selected isolates were used for phylogenetic analysis. Quantitative microbial risk assessment (QMRA) was conducted using the β-Poisson dose–response model. About 81% (58/72) of Asata River samples recorded Vibrio counts above 1.0 $$\times$$ × 103 cfu/100 mL. Of the fifty Vibrio isolates screened, its was detected in 54% (27/50), out of which 74% (20/27) had the ctx gene of toxigenic V. cholerae. Evolutionary relatedness of the sequenced isolates to V. cholerae was revealed. The estimated risks of cholera infection in persons exposed to untreated Asata River water were above 0.5 for all the exposure scenarios, for both the rainy and dry seasons. The risks were highest (~ 0.9) for exposure via drinking water and annual risk of infection was deduced to have a probability of 1.0. Therefore, dependence on the untreated Asata River water for drinking, recreational, domestic and irrigation purposes may present a potential public health risk of cholera outbreak. We recommend increased monitoring and surveillance of River water for Vibrio abundance and that Asata River be protected from further degradation.

Wastewater discharge and runoff waters are significant sources of human and animal fecal microbes in surface waters. Human-derived fecal contamination of water is generally estimated to pose a greater risk to human health than animal fecal contamination, but animals may serve as reservoirs of zoonotic pathogens. In this study, quantitative microbial risk assessment (QMRA) tools were used to evaluate the hygienic impact of sewage effluents and runoff water from municipalities and animal farms on surface and bathing waters. The humanspecific microbial source tracking (MST) marker HF183 was used to evaluate the dilution of fecal pathogens originating from the sewage effluent discharge to the downstream watershed. As novel risk management options, the efficiency of UV-LED disinfection and wetland treatment as well as biochar filtration was tested on-site for the contamination sources. According to the dilution pattern of the MST marker HF183, microbes from wastewater were diluted (2.3-3.7 log10) in the receiving waters. The scenario-based QMRA revealed, that the health risks posed by exposure to human-specific norovirus GII and zoonotic Campylobacter jejuni during the bathing events were evaluated. The risk for gastroenteritis was found to be elevated during wastewater contamination events, where especially norovirus GII infection risk increased (1-15 cases per day among 50 bathers) compared with the business as usual (BAU) situation (1 case per day). The noted C. jejuni infection risk was associated with animal farm contamination (1 case per day, versus 0.2-0.6 cases during BAU). Tertiary treatment of wastewater with wetland treatment and UV-LED disinfection effectively reduced the waterborne gastroenteritis risks associated with bathing. Based on the experiences from this study, a QMRA-based approach for health risk evaluations at bathing sites can be useful and is recommended for bathing site risk assessments in the future. In case of low pathogen numbers at the exposure sites, the MST marker HF183 could be used as a pathogen dilution coefficient for the watershed under evaluation. The full-scale implementation of novel tertiary treatment options at wastewater treatment plants (WWTPs) as well as on-site runoff water treatment options should be considered for infection risk management at locations where scenario-based QMRA implies elevated infection risks. [ABSTRACT FROM AUTHOR]

Canoeing is the most favorite recreational activity in several Taiwanese rivers. However, river water frequently contains elevated levels of pathogenic Escherichia coli, which has adverse effects on human health. This study adopted a quantitative microbial risk assessment to analyze seasonal risks to canoeists' health in the Dongshan River, Taiwan. First, river E. coli concentrations were statistically analyzed to determine the seasonal distributions. The exposure duration (ED) was determined by field observations. To propagate the parametric uncertainty, Monte Carlo simulation was employed to model the probability distributions of seasonal pathogenic E. coli levels, ingestion rates, and ED for athletes. Finally, the beta‐Poisson dose–response model was implemented to determine seasonal health risks for canoeists. The study results indicated that the health risks in infection probability ranged from 0.5 × 10−3 to 8.8 × 10−3 illnesses/person/day for tourists and 1.2 × 10−3 to 7.7 × 10−3 illnesses/person/day for athletes. The health risks in the Lizejian Bridge area for tourists exceeded an acceptable level suggested by the U.S. Environmental Protection Agency, 8 × 10−3 illnesses/person/day, in spring for an ED of 2 h/day, and the health risks for tourists and athletes approached this level in spring and winter for an ED exceeding or equaling 1.5 h/day. According to sensitivity analysis, the geometric standard deviation of river E. coli levels was the most sensitive parameter affecting seasonal risks to canoeists' health. To protect canoeists' health, effluent sewer systems, best management practices, and total maximum daily loads should be promptly implemented in this watershed. [ABSTRACT FROM AUTHOR]

Cholera infection results from the ingestion of water or food contaminated with toxigenic Vibrio cholerae. This study evaluated the occurrence of toxigenic V. cholerae in Asata River, Enugu Metropolis, Nigeria, and estimated V. cholerae infection risks from use of the River water for drinking, domestic and recreational purposes. Vibrio was detected and quantified using membrane filtration technique and thiosulfate–citrate–bile salts–sucrose agar. Isolates were screened by PCR, using specific primers targeting the internal transcribed spacer (its) region between 16 and 23S rRNA and the cholera toxin (ctx) gene. Sequenced 16SrRNA gene amplicons of two selected isolates were used for phylogenetic analysis. Quantitative microbial risk assessment (QMRA) was conducted using the β-Poisson dose–response model. About 81% (58/72) of Asata River samples recorded Vibrio counts above 1.0 × 103 cfu/100 mL. Of the fifty Vibrio isolates screened, its was detected in 54% (27/50), out of which 74% (20/27) had the ctx gene of toxigenic V. cholerae. Evolutionary relatedness of the sequenced isolates to V. cholerae was revealed. The estimated risks of cholera infection in persons exposed to untreated Asata River water were above 0.5 for all the exposure scenarios, for both the rainy and dry seasons. The risks were highest (~ 0.9) for exposure via drinking water and annual risk of infection was deduced to have a probability of 1.0. Therefore, dependence on the untreated Asata River water for drinking, recreational, domestic and irrigation purposes may present a potential public health risk of cholera outbreak. We recommend increased monitoring and surveillance of River water for Vibrio abundance and that Asata River be protected from further degradation. [ABSTRACT FROM AUTHOR]

Waterborne organisms in marine water generally originate from untreated wastewater discharged into the sea. The presence of numerous leisure beaches in Mahmoudabad city, Iran, annually attracts thousands of tourists from all over the country to participate in recreational swimming activities. This study probabilistically characterized the health risks associated with recreational swimming engendered by waterborne pathogens, such as intestinal enterococci and Escherichia coli (E. coli) at 15 sampling points along the beaches of the study using quantitative microbial risk assessment (QMRA). The mean annual infection risk of E. coli in children and adults was 0.424 and 0.229, respectively. The respective risk in terms of enterococci was 0.999 and 0.997, which were higher than the level recommended by the WHO and EPA. The results show that the risk of infection for children was higher than adults. Related authorities have to consider measures to improve environmental quality to protect tourists' and residents' well-being. [ABSTRACT FROM AUTHOR]

Spatiotemporal changes in waterborne disease risk were evaluated for the Chhnok Tru floating village in the Tonle Sap Lake by combining a hydraulic simulation and quantitative microbial risk assessment (QMRA). First, a three-dimensional (3D) hydraulic simulation was performed, and the transport of Escherichia coli (E. coli) was simulated. Prior to the simulation, by coupling satellite imagery analysis using the normalized difference water index (NDWI) and a sounding survey using an acoustic Doppler current profiler (ADCP), a new digital elevation model was generated for the complex channel network with high resolution. The results of the 3D hydraulic simulation revealed the flow regime and nonuniform pathogen distribution in the floating village. QMRA was performed for the village using the E. coli distribution calculated by the 3D hydraulic model. Subsequently, the disease risk in the village was visualized through an effective and easy-to-understand disease risk map. To demonstrate the usefulness of the hydraulic-simulation-based disease risk map, the map was used to quantitatively compare simple policies by evaluating their reduction in disease risk. [ABSTRACT FROM AUTHOR]

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Wastewater discharge and runoff waters are significant sources of human and animal fecal microbes in surface waters. Human-derived fecal contamination of water is generally estimated to pose a greater risk to human health than animal fecal contamination, but animals may serve as reservoirs of zoonotic pathogens. In this study, quantitative microbial risk assessment (QMRA) tools were used to evaluate the hygienic impact of sewage effluents and runoff water from municipalities and animal farms on surface and bathing waters. The human-specific microbial source tracking (MST) marker HF183 was used to evaluate the dilution of fecal pathogens originating from the sewage effluent discharge to the downstream watershed. As novel risk management options, the efficiency of UV-LED disinfection and wetland treatment as well as biochar filtration was tested on-site for the contamination sources. According to the dilution pattern of the MST marker HF183, microbes from wastewater were diluted (2.3–3.7 log10) in the receiving waters. The scenario-based QMRA revealed, that the health risks posed by exposure to human-specific norovirus GII and zoonotic Campylobacter jejuni during the bathing events were evaluated. The risk for gastroenteritis was found to be elevated during wastewater contamination events, where especially norovirus GII infection risk increased (1–15 cases per day among 50 bathers) compared with the business as usual (BAU) situation (1 case per day). The noted C. jejuni infection risk was associated with animal farm contamination (1 case per day, versus 0.2–0.6 cases during BAU). Tertiary treatment of wastewater with wetland treatment and UV-LED disinfection effectively reduced the waterborne gastroenteritis risks associated with bathing. Based on the experiences from this study, a QMRA-based approach for health risk evaluations at bathing sites can be useful and is recommended for bathing site risk assessments in the future. In case of low pathogen numbers at the exposure sites, the MST marker HF183 could be used as a pathogen dilution coefficient for the watershed under evaluation. The full-scale implementation of novel tertiary treatment options at wastewater treatment plants (WWTPs) as well as on-site runoff water treatment options should be considered for infection risk management at locations where scenario-based QMRA implies elevated infection risks.

The Dose Consumed step of the Poultry Food Assess Risk Model (PFARM) for Salmonella and chicken gizzards was presented and compared to the Exposure Assessment step of Quantitative Microbial Risk Assessment (QMRA). The specific objectives were 1) to demonstrate the dose consumed step of PFARM for Salmonella and chicken gizzards; 2) to compare Salmonella dose consumed from cooked chicken gizzards to that from cross-contaminated and temperature-abused lettuce; 3) to determine if Salmonella dose consumed changed over time in a production chain; and 4) to compare PFARM and QMRA predictions of Salmonella dose consumed. The PFARM and QMRA were developed in an Excel notebook and simulated with @Risk. Salmonella prevalence and number data (P = 100) for chicken gizzards (56 g) and scenario analysis were used to address objectives 1, 2, and 4, whereas running windows of 60 consecutive chicken gizzard samples and scenario analysis were used to address objective 3. A lot size of 1,000 kg of chicken gizzards was simulated. Mean portion size was 168 g resulting in the simulation of 5,952 meals per lot. Of these, 3.69 ± 0.32% and 0.49 ± 0.07% (mean ± SD) resulted in Salmonella dose consumed of ≥1 per meal from cooked chicken gizzards and lettuce, respectively. However, the total Salmonella dose consumed per lot from cooked chicken gizzards (272 ± 27) was less (P ≤ 0.05) than from lettuce (6,050 ± 4,929) because of a few highly contaminated (>310 Salmonella) lettuce portions at consumption. Over time in the production chain, Salmonella prevalence and total dose consumed per lot changed (P ≤ 0.05) but the patterns differed. The QMRA predicted higher (P ≤ 0.05) Salmonella dose consumed per meal than PFARM. In part, this was because QMRA only simulated contaminated grams, whereas PFARM simulated contaminated and non-contaminated meals. However, other factors, which are discussed, also contributed to the overestimation of Salmonella dose consumed by QMRA.

The aim of the study is to develop Salmonella spp. Quantitative microbial risk assessments (QMRA) and to evaluate the risk of Salmonellosis illness in the Taiwanese population after consumption of Taiwanese salty chicken (TSC). We assume that Salmonella spp. May contaminate the fresh raw chicken used in TSC. After transport to the diner, fresh raw chicken is received, cleaned, and surface-washed by diner staff. The TSC is then cooked and sold to consumers. We set four different cross-contamination scenarios to evaluate the contamination level of Salmonella spp. In TSC. We used a Monte Carlo simulation method, a probabilistic analysis method, and exceedance risk to evaluate the risk of Salmonellosis illness. When the exceedance risk was 5 %, and taking the Taiwanese population above 19 years old as an example, the rate of contracting Salmonellosis from the consumption of TSC will be 2.94 % (2.94 million per 100 million people) if the chef does not clean their hands, knives, or cutting boards. However, if the chef washes their hands, knives, and cutting boards with cold water and soap, the illness rate of Salmonellosis from consuming TSC will be 1.93E-04 % (193 per 100 million people). Sensitivity analysis indicates that the most important risk factor in the QMRAs of TSC is the temperature of the fresh raw chicken during transportation, following which were the Salmonella spp. Residual. If the staff of the diner separates the cooking tools used for raw ingredients and those for cooked food, the illness risk of Salmonellosis will be very low.

Quantitative microbial risk assessment (QMRA) can be used to evaluate health risks associated with recreational beach use. This study developed a site-specific risk assessment using a novel approach that combined quantitative PCR-based measurement of microbial source tracking (MST) genetic markers (human, dog, and gull fecal bacteria) with a QMRA analysis of potential pathogen risk. Water samples (n = 24) from two recreational beaches were collected and analyzed for MST markers as part of a broader Beach Exposure And Child Health Study that examined child behavior interactions with the beach environment. We report here the measurements of fecal bacteria MST markers in the environmental DNA extracts of those samples and a QMRA analysis of potential health risks utilizing the results from the MST measurements in the water samples. Human-specific Bacteroides was enumerated by the HF183 Taqman qPCR assay, gull-specific Catellicoccus was enumerated by the Gull2 qPCR assay, and dog-specific Bacteroides was enumerated by the DogBact qPCR assay. Derived reference pathogen doses, calculated from the MST marker concentrations detected in recreational waters, were used to estimate the risk of gastrointestinal illness for both children and adults. Dose-response equations were used to estimate the probability of the risk of infection (Pinf) per a swimming exposure event. Based on the QMRA simulations presented in this study, the GI risk from swimming or playing in water containing a mixture of human and non-human fecal sources appear to be primarily driven by the human fecal source. However, the estimated median GI health risk for both beaches never exceeded the U.S. EPA risk threshold of 32 illnesses per 1,000 recreation events. Our research suggests that utilizing QMRA together with MST can further extend our understanding of potential recreational bather risk by identifying the source contributing the greatest risk in a particular location, therefore informing beach management responses and decision-making. [ABSTRACT FROM AUTHOR]

With the increasing consumer demand for chilled meat, food safety issues related to chilled meat such as the prevalence and change of pathogenic bacteria during the processing, storage and consumption of chilled meat and their effects on public health have aroused great public concern. Quantitative microbial risk assessment (QMRA) is the core of chill meat safety risk analysis, which provides a theoretical basis for hazard analysis, determination of the critical control points and formulation of food safety goals and regulations. Since the promulgation of the Food Safety Law and the establishment of the Food Safety Risk Assessment Center in China, significant progress has been made in quantitative microbial risk assessment. In this paper, recent research on the quantitative risk assessment of common food-borne pathogens in livestock and poultry meat products is summarized, and recent progress in the application of process risk model, modular process risk model and omics technology in QMRA is reviewed. The current status of the application of quantitative microbial risk assessment in food safety management is summarized to provide reference for the development and application of quantitative microbial risk assessment in chilled meat.

Quantitative microbial risk assessment (QMRA) can be used to evaluate health risks associated with recreational beach use. This study developed a site-specific risk assessment using a novel approach that combined quantitative PCR-based measurement of microbial source tracking (MST) genetic markers (human, dog, and gull fecal bacteria) with a QMRA analysis of potential pathogen risk. Water samples (n = 24) from two recreational beaches were collected and analyzed for MST markers as part of a broader Beach Exposure And Child Health Study that examined child behavior interactions with the beach environment. We report here the measurements of fecal bacteria MST markers in the environmental DNA extracts of those samples and a QMRA analysis of potential health risks utilizing the results from the MST measurements in the water samples. Human-specific Bacteroides was enumerated by the HF183 Taqman qPCR assay, gull-specific Catellicoccus was enumerated by the Gull2 qPCR assay, and dog-specific Bacteroides was enumerated by the DogBact qPCR assay. Derived reference pathogen doses, calculated from the MST marker concentrations detected in recreational waters, were used to estimate the risk of gastrointestinal illness for both children and adults. Dose–response equations were used to estimate the probability of the risk of infection (Pinf) per a swimming exposure event. Based on the QMRA simulations presented in this study, the GI risk from swimming or playing in water containing a mixture of human and non-human fecal sources appear to be primarily driven by the human fecal source. However, the estimated median GI health risk for both beaches never exceeded the U.S. EPA risk threshold of 32 illnesses per 1,000 recreation events. Our research suggests that utilizing QMRA together with MST can further extend our understanding of potential recreational bather risk by identifying the source contributing the greatest risk in a particular location, therefore informing beach management responses and decision-making.

This study investigated seasonal variations in microbial contaminations of groundwater and associated health risks in four coastal communities (Essiama, Winneba, Accra, and Keta) in Ghana. Membrane filtration methods, sanitary risk inspection, and quantitative microbial risk assessment were employed, respectively, to (i) quantify bacteriological quality, (ii) identify risks to contamination, and (iii) assess health risks associated with Escherichia coli in groundwater. Results showed 70.00%, 53.33%, 70.37% and 90.00% of groundwater sources in Essiama, Winneba, Accra, and Keta, respectively, were at intermediate risk, whereas 3.33%, 40.00%, 14.81%, and 3.33%, respectively, were at high risk. Very high-risk levels of contamination were recorded only in Accra. The presence of animal wastes within a 10 m radius of groundwater collection point, bad drainage systems, collection of spilt water in apron area, the use of ropes and buckets when fetching groundwater, and absence of aprons and well covers put more than 60.00% of the groundwater points in two or more locations at risk of contaminations. Assessment of bacteriological quality of groundwater indicated that mean total coliforms and E. coli ranged, respectively, between 123.40-501.30 and 30.98–141.90 CFU/100 ml for the communities; the highest microbial counts for dry and wet seasons occurred in Winneba and Keta, respectively. Seasonal variations in E. coli counts in Winneba and Accra were significantly higher in the dry season than in the wet season; Essiama and Keta showed no significant seasonal variations. Exposure to E. coli O157:H7 through drinking groundwater ranged between 5 and 23 cells per day. Although exposure to E. coli O157:H7 through bathing was less than 1 cell per day in all communities, residents were exposed to one E. coli, at least, every 62, 141, 237, and 282 days in Winneba, Accra, Keta, and Essiama, respectively. The risk of infection and illness for all communities was 1 for drinking, whereas that for bathing ranged from 0.57 to 0.98. The estimated Disability-Adjusted Life Years (DALY) exceeded the WHO-acceptable DALY. These findings show that groundwater resources in the selected coastal communities were prone to microbial contaminations, and this may be a setback to Sustainable Development Goals 6. Implications of the findings are discussed.

The conservation of freshwater is of both global and national importance, and in the United States, agriculture is one of the largest consumers of this resource. Reduction of the strain farming puts on local surface or groundwater is vital for ensuring resilience in the face of climate change, and one possible option is to irrigate with a combination of freshwater and reclaimed water from municipal wastewater treatment facilities. However, this wastewater can contain pathogens that are harmful to human health, such as Legionella pneumophila, which is a bacterium that can survive aerosolization and airborne transportation and cause severe pneumonia when inhaled. To assess an individual adult's risk of infection with L. pneumophila from a single exposure to agricultural spray irrigation, a quantitative microbial risk assessment was conducted for a scenario of spray irrigation in central Illinois, for the growing seasons in 2017, 2018, and 2019. The assessment found that the mean risk of infection for a single exposure exceeded the safety threshold of 10–6 infections/exposure up to 1 km from a low‐pressure irrigator and up to 2 km from a high‐pressure irrigator, although no median risk exceeded the threshold for any distance or irrigator pressure. These findings suggest that spray irrigation with treated municipal wastewater could be a viable option for reducing freshwater consumption in Midwest farming, as long as irrigation on windy days is avoided and close proximity to the active irrigator is limited. [ABSTRACT FROM AUTHOR]

Refill drinking water has been popular due to its low price and practicality, but the quality is still questionable. Data from the Health Office of Pariaman City stated that based on laboratory tests on the quality of drinking water from the drinking-water refill depots in Pariaman City, it showed that every year more than 50% of drinking water from the drinking-water refill depots do not meet the health requirements for drinking water. This study aimed to investigate the health risks of refill drinking water generated from 78 drinking-water refill depots spread across four sub-districts in Pariaman City. Using the Quantitative Microbial Risk Assessment calculation, the risk calculation used drinking-water refill depots laboratory examination data from the Pariaman City Health Office in 2020. It was found that there was a high risk of infection from E. coli contamination in refill drinking water, where the highest risk was in the North Pariaman District with an annual risk of disease for individuals of 5,14x10-1. This showed the ineffectiveness of drinking-water refill depots in eliminating bacteria and lousy hygiene and sanitation practices. An approach is needed for the owners and operators of drinking water refill depots to improve the tools' effectiveness and education on hygiene and sanitation for drinking-water refill depots operators to maintain patient safety and health. [ABSTRACT FROM AUTHOR]

Estimating the risk of infections or other outcomes incident to pathogen exposure is a primary goal of quantitative microbial risk assessment (QMRA). Such estimates are useful to predict population‐level risks, to evaluate exposures based on normative or tolerable risk guidelines, and to interpret the likely public health relevance of microbial measurements in environmental media. To evaluate alternative control measures (interventions), ratio estimates of effect (e.g., odds and risk ratios) are needed that are more broadly interpretable in the health sciences and consistent with convention in epidemiology. In this paper, we propose a general method for estimating widely used ratio measures of effect derived from stochastic QMRA approaches, including the generation of appropriate confidence intervals. Such QMRA‐derived ratios can be used as a basis for evaluating interventions via hypothesis testing and for inclusion in systematic reviews and meta‐analyses in a form consistent with risk estimation approaches commonly used in epidemiology. [ABSTRACT FROM AUTHOR]

Purpose of reviewFomites are inanimate objects that become colonized with microbes and serve as potential intermediaries for transmission to/from humans. This review summarizes recent literature on fomite contamination and microbial survival in the built environment, transmission between fomites and humans, and implications for human health.Recent findingsApplications of molecular sequencing techniques to analyze microbial samples have increased our understanding of the microbial diversity that exists in the built environment. This growing body of research has established that microbial communities on surfaces include substantial diversity, with considerable dynamics. While many microbial taxa likely die or lay dormant, some organisms survive, including those that are potentially beneficial, benign, or pathogenic. Surface characteristics also influence microbial survival and rates of transfer to and from humans. Recent research has combined experimental data, mechanistic modeling, and epidemiological approaches to shed light on the likely contributors to microbial exchange between fomites and humans and their contributions to adverse (and even potentially beneficial) human health outcomes.SummaryIn addition to concerns for fomite transmission of potential pathogens, new analytical tools have uncovered other microbial matters that can be transmitted indirectly via fomites, including entire microbial communities and antibiotic-resistant bacteria. Mathematical models and epidemiological approaches can provide insight on human health implications. However, both are subject to limitations associated with study design, and there is a need to better understand appropriate input model parameters. Fomites remain an important mechanism of transmission of many microbes, along with direct contact and short- and long-range aerosols.

The present research estimated the impact of storage on the microbial quality of high-density polyethylene drinking water. Samples were taken from two popular companies in Greater Accra using a two-sided exact test in SAS JMP to estimate the sample size. The samples were stored across three temperature profiles at 8 °C, 30 °C (average room temperature), and 40 °C (average outdoor temperature) for 28 days. The samples were examined using standard microbiological methods for heterotrophic plate counts (HPCs), faecal coliforms, and Escherichia coli. The data were described and regressed with Microsoft Excel, Argo 4.3.1, and SAS JMP software. The results demonstrated increasing deterioration of the water samples for all microbial indices at all temperatures with increasing storage duration. The highest HPC, faecal coliforms, and E. coli were 1,312; 622; and 252 cfu/100 mL, respectively, all at 40 °C. The daily risk of infection due to E. coli O157:H7 was 5.22 × 10−5 infections per child per day for children under 5 years, and 1.6 × 10−4 attacks per adult per day, compared to the upper limit of 1.0 × 10−6. These results are higher than recommended exposures, and interventions along the sachet drinking water value chain are needed to protect public health. HIGHLIGHTS Sachet water contributes to water security in Ghana.; HPC, faecal coliforms, and Escherichia coli were 1,312; 622; and 252 cfu/100 mL, respectively.; The mean daily morbidity was between 5.33 × 10−5 and 2.36 × 10−2 infections per person per day.; Daily and annual rates of infections were higher than the recommended limit of 1 × 10−6.; Between 22,700 and 30,189 children under 5 stood the risk of enteric infections from E. coli O157:H7.;

This study evaluated Clostridium perfringens risk in fermented bean pastes. The prevalence in fermented bean pastes, development of the predictive model, temperature, time, and consumption data were investigated. A simulation model was prepared in @RISK with the obtained data to calculate the probability of foodborne C. perfringens foodborne illness from fermented bean paste consumption. Only 74 of the 1,097 samples were positive for C. perfringens. The initial contamination level was estimated to be 0.7 log CFU/g. It showed the probability of foodborne C. perfringens infection per person per day upon consumption of fermented bean pastes was 8.0×10-12, which is considered low risk. [ABSTRACT FROM AUTHOR]

Cryptosporidium and Giardia (major causes of diarrhea) are widely distributed in Chinese source waters and threaten human health. A new spatially explicit GloWPa-TGR-Crypt-Giar C1 model is presented to simultaneously estimate mean monthly (oo)cyst concentrations in surface and ground waters in the Three Gorges Reservoir (TGR) watershed. A quantitative risk assessment of protozoal infections considered different source waters, transmission pathways, regions, susceptible subpopulations, and drinking water treatments. Monthly mean Cryptosporidium oocyst and Giardia cyst concentrations ranged between 0.5–19.3 oocysts/10 L and 0.2–5.0 cysts/10 L in surface water, respectively, and 0.007–0.3 oocysts/10 L and 0.002–0. 2 cysts/10 L in groundwater. The cumulative disease burdens attributable to cryptosporidiosis and giardiasis were, respectively, 5.77×10−5 DALYs (disability-adjusted life years/person/year) and 4.63×10−6 DALYs in urban areas, and 6.35×10−4 DALYs and 8.84×10−5 DALYs in rural areas, which were much higher than the reference risk level recommended by the World Health Organization ( 10 - 6 DALYs). The annual burden associated with consuming surface water was calculated to be 3.84×10−4 DALYs for Cryptosporidium and 5.10 × 10 - 5 DALYs for Giardia, whereas consuming groundwater entailed the lower burdens (1.26×10−5 and 3.50×10−6 DALYs, respectively). Most DALYs were a consequence of consumption of directly supplied surface water. Fifty percent of the health burden was carried by immunodeficiency with HIV. Children (0–4 years) were more likely to have an individual disease burden than adults (15–64 years). Males were more susceptible than females. Improving sanitation through adequate ozone and microfiltration treatment should be considered when attempting to reduce disease burden. Sensitivity analysis highlighted the importance of reducing (oo)cyst loads to protect the watershed. The methodology and results described will help in evaluating and reducing the burden of protozoal infection associated with surface and ground waters in the TGR and similar watersheds. [ABSTRACT FROM AUTHOR]

Background: Wastewater treatment plants (WWTPs) are a source of airborne bacterial contamination that can pose health risks to staff. The aim of this study was to evaluate seasonal variations in the health risks of exposure to Staphylococcus aureus bioaerosols using the quantitative microbial risk assessment (QMRA) approach in a WWTP in Hamadan, Iran. Study Design: This was a descriptive cross-sectional study. Methods: This study determined the emission concentrations of S. aureus bioaerosols in summer and winter. Then, the health risks of three exposure scenarios (the worker, field engineer, and laboratory technician) were evaluated using the QMRA approach. The bioaerosol samples were collected every 12 days in both summer and winter of 2021 with a nutrient agar using a single-stage cascade impactor (Quick Take 30, SKC Inc.) in both outdoor and indoor environments. Results: The results demonstrated that in both seasons, S. aureus bioaerosol concentrations in outdoor and indoor environments were below the standard established by the American Conference of Governmental Industrial Hygienists (500 CFU/m3). While in summer, the annual infection risks and the disease burden for the three exposure scenarios in both outdoor and indoor environments were higher than the United States Environmental Protection Agency (≤ 10-4 pppy) and the World Health Organization (WHO) (≤ 10-6 DALYs pppy-1) benchmarks, respectively. Conclusion: The findings provided high health risks for staff in the three exposure scenarios of an indoor environment, which should not be ignored, as well as emphasizing the use of the QMRA approach to estimate health risks caused by occupational exposure to bioaerosols and taking executive measures to protect staff working in the WWTPs. [ABSTRACT FROM AUTHOR]

A large number of pathogenic bioaerosols are generated during the treatment process of wastewater treatment plants (WWTPs), and they can pose potential risks to human health. Therefore, this study systematically analyzed the emission characteristics of Staphylococcus aureus bioaerosols released from an inverted umbrella aeration tank, a microporous aeration tank, and a residual sludge storage yard in a WWTP, and quantitatively evaluated the health risks of four kinds of exposed populations with nasal/oral breathing patterns under optimistic and conservative estimations. The results displayed that the bioaerosol concentration in inverted umbrella aeration tank was higher than that in microporous aeration tank and residual sludge storage yard. Aerosolization ratio in residual sludge storage yard was an order of magnitude lower than that in aeration tanks. Sludge workers were at higher health risks than the other three exposed populations. The health risks of nasal breathers (infection risk: 1.62 × 10−5–2.56 × 10−3 pppy; disease burden: 4.24 × 10−8–6.72 × 10−6 DALYs pppy) were 0.61–0.63 times higher than those of oral breathers (infection risk: 9.95 × 10−6–1.59 × 10−3 pppy; disease burden: 2.61 × 10−8–4.18 × 10−6 DALYs pppy). For female field engineers using oral breathing, laboratory technicians, and researchers without personal protective equipment (PPE), infection risk and disease burden had the opposite results, which indicated that satisfying one certain benchmark did not mean absolute safety. In addition, health risks of exposed populations were reduced by an order of magnitude after wearing PPE. This study can provide a reliable theoretical basis for the risk prevention of bioaerosols and supply data support for the strategies of health risk control perspectives for local sewage utilities. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A quantitative microbial risk assessment was conducted to assess the health risks associated with the exposure of agricultural workers to tertiary treated wastewater in irrigated fields through soil ingestion in Cyprus. Three pathogenic microorganisms were chosen, particularly E. coli (bacteria), rotavirus (viruses) and Cryptosporidium. Two extreme exposure scenarios were investigated. Monte Carlo simulations were performed using input data from literature, and the model outputs were compared to the health standards of the World Health Organization (WHO). The results suggested that additional treatment is required for all pathogens to satisfy the health standards. Sensitivity analysis identified the source concentration and pathogen reduction due to soil aquifer passage as the most influential factors in the model outputs. Additional computations were performed to evaluate the minimum pathogen reduction due to soil aquifer passage so that the health targets are achieved for the 95 % of the output values. Rotavirus and Cryptosporidium were found to require more treatment than E. coli. The inclusion of these reference pathogens to the monitoring network of the local authorities is recommended, and the role of soil aquifer passage is emphasized on reducing the concentration of the contaminants. [ABSTRACT FROM AUTHOR]

The Illness Dose (ID) step of a Poultry Food Assess Risk Model (PFARM) for Salmonella and chicken gizzards (CGs) was shown in the present study. The illness dose is the minimum dose of Salmonella consumed that causes an illness. It depends on the zoonotic potential (ZP) of Salmonella, food consumption behavior (FCB), and consumer health and immunity (CHI) or the disease triangle (DT). Zoonotic potential is the ability of Salmonella to survive, grow, and spread in the production chain or food and then cause illness in humans. Illness dose is predicted in PFARM using a DT, dose-response model (DRM) that was developed with human feeding trial (HFT) data and was validated with human outbreak investigation (HOI) data for Salmonella. The ability of the DT, DRM to predict DR data from HOI and HFT for Salmonella was quantified using the Acceptable Prediction Zone (APZ) method where acceptable performance occurred when the proportion of residuals in the APZ (pAPZ) was ≥0.7. United States, Centers for Disease Control and Prevention (CDC) data for human salmonellosis from 2007 to 2016 were used to simulate ZP, and only minor changes in ZP of 11 Salmonella serotypes were observed during this time. The performance of the DT, DRM for predicting Salmonella DR data from HFT and HOI was acceptable with pAPZ that ranged from 0.87 to 1 for individual serotypes of Salmonella. Simulation results from the DT, DRM in PFARM indicated that ID decreased (P ≤ 0.05) and ZP increased (P ≤ 0.05) over time in the simulated production chain because the main serotype of Salmonella changed from Kentucky (low ZP) to Infantis (high ZP) while FCB and CHI were held constant. These results indicated that the DT, DRM in PFARM can be used with confidence to predict ID as a function of ZP, FCB, and CHI. In other words, the DT, DRM in PFARM can be used with confidence to predict dose-response for Salmonella and CGs.

Spatiotemporal changes in waterborne disease risk were evaluated for the Chhnok Tru floating village in the Tonle Sap Lake by combining a hydraulic simulation and quantitative microbial risk assessment (QMRA). First, a three-dimensional (3D) hydraulic simulation was performed, and the transport of Escherichia coli (E. coli) was simulated. Prior to the simulation, by coupling satellite imagery analysis using the normalized difference water index (NDWI) and a sounding survey using an acoustic Doppler current profiler (ADCP), a new digital elevation model was generated for the complex channel network with high resolution. The results of the 3D hydraulic simulation revealed the flow regime and nonuniform pathogen distribution in the floating village. QMRA was performed for the village using the E. coli distribution calculated by the 3D hydraulic model. Subsequently, the disease risk in the village was visualized through an effective and easy-to-understand disease risk map. To demonstrate the usefulness of the hydraulic-simulation-based disease risk map, the map was used to quantitatively compare simple policies by evaluating their reduction in disease risk.

Biological treatment in wastewater treatment plants releases high amounts of pathogenic bioaerosols. Quantitative microbial risk assessment is a framework commonly used for quantitative risk estimation for occupational exposure scenarios. However, the quantitative contributions of health-risk-estimate inputted parameters remain ambiguous. Therefore, this research aimed to study the disease burden of workers exposed to Staphylococcus aureus bioaerosol during warm and cold periods and strictly quantify the contributions of the inputted parameters by sensitivity analysis on the basis of Monte Carlo simulation. Results showed that the disease health risk burden of workers in the warm period was 1.15–6.11 times higher than that of workers in the cold period. The disease health risk burden of workers without personal protective equipment was 23.83–36.55 times higher than that of workers with personal protective equipment. Sensitivity analysis showed that exposure concentration and aerosol ingestion rate were the first and second predominant factors, respectively; the sensitivity partitioning coefficient of the former was 1.17–1.35 times the value of the latter. In addition, no remarkable differences were revealed in the sensitivity percentage ratio between warm and cold periods. The findings could contribute to the mitigation measures for the management of public health risks. [ABSTRACT FROM AUTHOR]

[Display omitted] • An integrated model predicted pollution changes and assessed the risks of E. coli. • The pollution levels in the tributary basin surpassed those in the mainstream basin. • Three exposure pathways exceeded the acceptable risk level recommended by the WHO. • Strategies for point pollution were more effective in reducing disease burdens. Escherichia coli (E. coli), a typical fecal coliform, can enter surface rivers through daily wastewater and septic effluents, as well as the use of fecal fertilizers. Pathogenic strains of E. coli pose a significant public health risk. Despite China's rapid economic and social development, sanitation and watershed management still face challenges. In this study, we employ a combined model of the Soil and Water Assessment Tool and Quantitative Microbial Risk Assessment to predict pollution changes, considering social development and climate change. Our aim is to quantify the risks and assess pollution prevention strategies for E. coli in the Three Gorges Reservoir (TGR) region. The results indicated that under moderate development, the average E. coli concentrations and disease burdens were 367 ± 75 CFU/100 mL and 23.4 (95 % Confidence Interval (CI): 2.8–72.6) Disability-Adjusted Life Years (DALYs, per 1,000,000 population per year), respectively. Under rapid development, these values were 330 ± 58 CFU/100 mL and 21.2 (95 % CI: 2.6–65.1) DALYs, respectively. Implementing a point strategy, mainly increasing sewage collection rates, could reduce E. coli concentrations by approximately 30 % and disease burdens by 27–28 %. For a diffuse strategy, primarily extending composting duration, reductions of 9 % in E. coli concentrations and 7–8 % in disease burdens were observed. Combining both strategies resulted in a 40 % decrease in E. coli concentrations and 35–36 % reduction in disease burdens. This model, incorporating social development, climate change, and microbial risk, provides insights into predicting pollution changes and evaluating the effectiveness of prevention strategies for E. coli in the TGR region and similar watersheds. [ABSTRACT FROM AUTHOR]

The present research estimated the impact of storage on the microbial quality of high-density polyethylene drinking water. Samples were taken from two popular companies in Greater Accra using a two-sided exact test in SAS JMP to estimate the sample size. The samples were stored across three temperature profiles at 8 °C, 30 °C (average room temperature), and 40 °C (average outdoor temperature) for 28 days. The samples were examined using standard microbiological methods for heterotrophic plate counts (HPCs), faecal coliforms, and Escherichia coli. The data were described and regressed with Microsoft Excel, Argo 4.3.1, and SAS JMP software. The results demonstrated increasing deterioration of the water samples for all microbial indices at all temperatures with increasing storage duration. The highest HPC, faecal coliforms, and E. coli were 1,312; 622; and 252 cfu/100 mL, respectively, all at 40 °C. The daily risk of infection due to E. coli O157:H7 was 5.22x10-5 infections per child per day for children under 5 years, and 1.6x10-4 attacks per adult per day, compared to the upper limit of 1.0x10-6. These results are higher than recommended exposures, and interventions along the sachet drinking water value chain are needed to protect public health. [ABSTRACT FROM AUTHOR]

We developed an environmental exposure model to estimate the coronavirus disease 2019 (COVID-19) risk among participants at outdoor music festivals and validated the model using two real events--one in Japan (Event 1) and one in Spain (Event 2). Furthermore, we considered a hypothetical situation in which Event 1 was held but enhanced measures were implemented to evaluate the extent to which the risk could be reduced by additional infection control measures, such as negative antigen tests on the day of the event, wearing of masks, disinfection of environmental surfaces, and vaccination. Among 7,392 participants, the total number of already- and newly-infected individuals who participated in Event 1 according to the new model was 47.0 (95% uncertainty interval: 12.5-185.5), which is in good agreement with the reported value (45). The risk of infection at Event 2 (1.98×10-2; 95% uncertainty interval: 0.55×10-2-6.39×10-2), calculated by the model in this study, was also similar to the estimated value in the previous epidemiological study (1.25×10-2). These results for the two events in different countries highlighted the validity of the model. Among the additional control measures in the hypothetical Event 1, vaccination, mask-wearing, and disinfection of surfaces were determined to be effective. Based on the combination of all measures, a 94% risk reduction could be achieved. In addition to setting a benchmark for an acceptable number of newly-infected individuals at the time of an event, the application of this model will enable us to determine whether it is necessary to implement additional measures, limit the number of participants, or refrain from holding an event. [ABSTRACT FROM AUTHOR]

The use of wastewater for non-potable purposes is an important alternative for addressing water scarcity, especially in developing regions. However, minimizing the risks, particularly those associated with emerging contaminants that may induce resistance among pathogens in wastewater, is crucial. This study assessed the occurrence of antibiotic-resistant bacteria in untreated wastewater used for agricultural purposes and evaluated the quantifiable health risks associated with this practice in Tamale, Ghana. The resistance of some Enterobacteriaceae, such as E. coli, Klebsiella, and Salmonella-Shigella, to four commonly used antibiotics in Ghana was assessed using a conventional microbiological culture approach and the Kirby Bauer disk diffusion method. A Quantitative Microbial Risk Assessment (QMRA) was performed to estimate the health risks associated with two distinct scenarios of wastewater reuse: (1) accidental ingestion of contaminated wastewater and soil, and (2) consumption of vegetables irrigated with wastewater. This approach applied a Monte Carlo simulation based on 10,000 interactions and identified E. coli O157:H7 as the reference pathogen. Among Enterobacteriaceae, Klebsiella pneumoniae, Salmonella-Shigella and E. coli were isolated, in concentrations exceeding the limit recommended by the World Health Organization (10 3  CFU/100 ml). All the isolated bacteria were resistant to metronidazole (5 μg). Thirty-three per cent of Klebsiella pneumoniae isolates were intermediate/moderately susceptible, and all other bacteria were resistant to amoxicillin (30 μg). All Klebsiella pneumoniae and the majority of Salmonella-Shigella (69.8 %) isolates were resistant to trimethoprim-sulfamethoxazole (25 μg) and tetracycline (30 μg). When assessing health risks, the mean annual probability of infection associated with consuming vegetables irrigated with wastewater varied between 5.14 × 10 -2 and 9.79 × 10 -1 per person per year. Conversely, for the accidental ingestion scenario, the probability was 1.00 per person per year. In these scenarios, the probability of illness ranged from 1.29 × 10 -2 to 2.4 × 10 -1 and 2.5 × 10 -1 per person per year. The health risks posed by these findings surpass the maximum threshold prescribed by the World Health Organization, thereby emphasizing the need for prompt mitigation strategies., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sanitation workers provide essential services that protect public health, often at the cost of their own health and safety. In this study, we evaluate occupational exposure to fecal pathogens at each stage in a non-sewered sanitation process. Bulk fecal waste samples were collected during waste collection and waste processing tasks and analyzed for Cryptosporidium, adenovirus, E. coli, and total coliforms using quantitative polymerase chain reaction and culture methods. Structured observations of worker hand-to-mouth behavior were conducted, and worker hand- and glove-rinse samples were collected and analyzed for E. coli and total coliforms. A Monte Carlo simulation was used to model the dose of pathogen ingested and the risk of disease across two waste collection and processing tasks. The model results show that the probability of disease was highest from exposure to adenovirus during collection. Our analysis highlights that pathogen-to-indicator ratios are useful for predicting the risk to adenovirus which has a high detection rate. On the other hand, the use of pathogen-to-indicator ratios to predict Cryptosporidium concentration is fraught due to variable detection rates and concentration. HIGHLIGHTS This study outlines methods for conducting quantitative microbial risk assessments in low-resource settings.; Pathogen-to-indicator ratios specific to this study are constructed from primary data in order to minimize model uncertainty.; The probability of pathogen infection and disease was estimated for sanitation workers at each stage in a municipal scale fecal waste collection and waste-to-fuel process.;

Although reclaimed water for potable applications has many potential benefits, it poses concerns for chemical and microbial risks to consumers. We present a quantitative microbial risk assessment (QMRA) Monte Carlo framework to compare a de facto water reuse scenario (treated wastewater-impacted surface water) with four hypothetical Direct Potable Reuse (DPR) scenarios for Norovirus, Cryptosporidium, and Salmonella. Consumer microbial risks of surface source water quality (impacted by 0-100% treated wastewater effluent) were assessed. Additionally, we assessed risks for different blending ratios (0-100% surface water blended into advanced-treated DPR water) when source surface water consisted of 50% wastewater effluent. De facto reuse risks exceeded the yearly 10-4 infections risk benchmark while all modeled DPR risks were significantly lower. Contamination with 1% or more wastewater effluent in the source water, and blending 1% or more wastewater-impacted surface water into the advanced-treated DPR water drove the risk closer to the 10-4 benchmark. We demonstrate that de facto reuse by itself, or as an input into DPR, drives microbial risks more so than the advanced-treated DPR water. When applied using location-specific inputs, this framework can contribute to project design and public awareness campaigns to build legitimacy for DPR.

The annual consumption of fishery products, particularly sea squirt (Halocynthia roretzi), per person has steadily increased in South Korea. However, the quantitative risk of Vibrio parahaemolyticus following intake of sea squirt has not been analyzed. This study focuses on quantitative predictions of the probability of consuming sea squirt and getting of V. parahaemolyticus foodborne illness. The prevalence of V. parahaemolyticus in sea squirt was evaluated, and the time spent by sea squirt in transportation vehicles, market displays, and home refrigerators, in addition to the temperature of each of these, were recorded. The data were fitted to the @RISK program to obtain a probability distribution. Predictive models were developed to determine the fate of V. parahaemolyticus under distribution conditions. A simulation model was prepared based on experimental data, and a dose-response model for V. parahaemolyticus was prepared using data from literature to estimate infection risk. V. parahaemolyticus contamination was detected in 6 of 35 (17.1%) sea squirt samples. The daily consumption quantity of sea squirt was 62.14 g per person, and the consumption frequency was 0.28%. The average probability of V. parahaemolyticus foodborne illness following sea squirt consumption per person per day was 4.03 × 10−9. The objective of this study was to evaluate the risk of foodborne illness caused by Vibrio parahaemolyticus following sea squirt consumption in South Korea.

Occupational exposure to pathogens can pose health risks. This study investigates the viral exposure of workers in a wastewater treatment plant (WWTP) and a swine farm by analyzing aerosol and surfaces samples. Viral contamination was evaluated using quantitative polymerase chain reaction (qPCR) assays, and target enrichment sequencing (TES) was performed to identify the vertebrate viruses to which workers might be exposed. Additionally, Quantitative Microbial Risk Assessment (QMRA) was conducted to estimate the occupational risk associated with viral exposure for WWTP workers, choosing Human Adenovirus (HAdV) as the reference pathogen. In the swine farm, QMRA was performed as an extrapolation, considering a hypothetical zoonotic virus with characteristics similar to Porcine Adenovirus (PAdV). The modelled exposure routes included aerosol inhalation and oral ingestion through contaminated surfaces and hand-to-mouth contact. HAdV and PAdV were widespread viruses in the WWTP and the swine farm, respectively, by qPCR assays. TES identified human and other vertebrate viruses WWTP samples, including viruses from families such as Adenoviridae , Circoviridae , Orthoherpesviridae , Papillomaviridae, and Parvoviridae. In the swine farm, most of the identified vertebrate viruses were porcine viruses belonging to Adenoviridae , Astroviridae , Circoviridae , Herpesviridae , Papillomaviridae , Parvoviridae , Picornaviridae, and Retroviridae. QMRA analysis revealed noteworthy risks of viral infections for WWTP workers if safety measures are not taken. The probability of illness due to HAdV inhalation was higher in summer compared to winter, while the greatest risk from oral ingestion was observed in workspaces during winter. Swine farm QMRA simulation suggested a potential occupational risk in the case of exposure to a hypothetical zoonotic virus. This study provides valuable insights into WWTP and swine farm worker's occupational exposure to human and other vertebrate viruses. QMRA and NGS analyses conducted in this study will assist managers in making evidence-based decisions, facilitating the implementation of protection measures, and risk mitigation practices for workers. • Human pathogenic viruses from wastewater are present in WWTP aerosol and surfaces. • Swine farm workers are exposed to a high diversity of porcine viruses. • Occupational risk could be faced by WWTP workers if measures are not taken. • Monitoring and surveillance tools are crucial to detect emerging zoonotic pathogens. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes can survive in yogurt stored at a refrigeration temperature. Enterohemorrhagic Escherichia coli (EHEC) has a strong acid resistance that can survive in the yogurt with a low pH. We estimated the risk of L. monocytogenes and EHEC due to yogurt consumption with @Risk. Predictive survival models for L. monocytogenes and EHEC in drinking and regular yogurt were developed at 4, 10, 17, 25, and 36 °C, and the survival of both pathogens in yogurt was predicted during distribution and storage at home. The average initial contamination level in drinking and regular yogurt was calculated to be −3.941 log CFU/g and −3.608 log CFU/g, respectively, and the contamination level of both LM and EHEC decreased in yogurt from the market to home. Mean values of the possibility of illness caused by EHEC were higher (drinking: 1.44 × 10−8; regular: 5.09 × 10−9) than L. monocytogenes (drinking: 1.91 × 10−15; regular: 2.87 × 10−16) in the susceptible population. Both pathogens had a positive correlation with the initial contamination level and consumption. These results show that the foodborne illness risk from L. monocytogenes and EHEC due to yogurt consumption is very low. However, controlling the initial contamination level of EHEC during yogurt manufacture should be emphasized. [ABSTRACT FROM AUTHOR]

Shared sanitation facilities have been hailed as an innovative approach to solve the challenge with sanitation access. However, these facilities may act as hotspots for disease transmission due to unhygienic conditions. In this study we used quantitative (based on Escherichia coli contamination) techniques to assess the health risks associated with the use of community ablution blocks (CABs). The most contaminated surfaces were the cistern handle (5.7 Log10 cfu/cm2) and internal pull latch (5.8 Log10 cfu/cm2). Based on the E. coli contamination, at least two people out of 100 CAB users might be potentially infected when they touch "hot" surfaces. These risks were modelled assuming transfer of potentially pathogenic E. coli from these surfaces to the mouth. The incorporation of risk-reduction measures, such as wiping of these surfaces or washing of hands, could potentially result in significant reduction of infection risks. The most significant risk-reduction intervention was determined to be wiping of the contact surfaces, especially twice prior to contact. A combination of risk-reduction interventions could further reduce the risks. This study shows that contamination of contact surfaces within shared CABs could lead to increased risks of infections, requiring measures aimed at reducing the associated risks. The risk assessment framework used in this study could therefore be applied in similar settings to estimate associated health risks with the use of such facilities. [ABSTRACT FROM AUTHOR]

Aims: The biological events occurring during human digestion help to understand the mechanisms underlying the dose–response relationships of enteric bacterial pathogens. To better understand these events, we investigated the growth and reduction behaviour of bacterial pathogens in an in vitro model simulating the environment of the small intestine. Methods and Results: The foodborne pathogens Campylobacter jejuni, Listeria monocytogenes and Escherichia coli O157:H7 were cultured with multiple competing enteric bacteria. Differences in the pathogen's growth kinetics due to the relative amount of competing enteric bacteria were investigated. These growth differences were described using a mathematical model based on Bayesian inference. When pathogenic and enteric bacteria were inoculated at 1 log CFU per ml and 9 log CFU per ml, respectively, L. monocytogenes was inactivated over time, while C. jejuni and E. coli O157:H7 survived without multiplying. However, as pathogen inocula were increased, its inhibition by enteric bacteria also decreased. Conclusions: Although the growth of pathogenic species was inhibited by enteric bacteria, the pathogens still survived. Significance and Impact of the Study: Competition experiments in a small‐intestine model have enhanced understanding of the infection risk in the intestine and provide insights for evaluating dose–response relationships. [ABSTRACT FROM AUTHOR]

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

Broiler litter (BL) is often contaminated by a variety of zoonotic pathogens. This study attempts to assess the persistence of Salmonella enterica serovar Infantis (S. Infantis) in BL based on spatial and temporal variation of physicochemical properties in a stockpile and composting sleeve. A single trial of two pilot-scale setups, ~35 m3 each, included an open static pile (stockpile) and composting in a polyethylene sleeve with forced aeration. The initial water content was adjusted only for the sleeve (~50% w/w) as in a common composting practice. Both systems were monitored weekly and then biweekly during 2 months in 47–53 sampling points each on every campaign. Measurements included temperature, water content, pH, electrical conductivity (EC), gas-phase oxygen, and ammonia, and the collected data were used to construct multiple contour grid maps. Of the stockpile volume, 83, 71, and 62% did not reach the commonly required minimum temperature of 55°C for three consecutive days during the first, second, and third weeks, respectively. Oxygen levels showed a strong gradient across the stockpile, while anaerobic conditions prevailed in the core. Variation was also recorded within the sleeve, but due to the water content adjustment and active aeration, the conditions favored more intense degradation and higher temperatures. Combining the grid maps drawn in this study with decay rate constants recently published for S. Infantis in BL under 36 combinations of temperature, water content, and pH, we assessed the spatial persistence of S. Infantis in the stockpile and the sleeve. Temperature was shown as a major factor, while water content and pH had only a small effect, in the stockpile only. Co-correlations between temperature, water content, EC, and oxygen suggest that selected physicochemical properties may be sufficient for such assessments. Up to 3 weeks would be recommended to achieve 7–8 log10 reduction in Salmonella in a stockpile, while this would be fully achieved within 1 week in a sleeve. This approach of combining high-resolution spatial field sampling along with decay rates of pathogens under controlled lab conditions may improve quantitative microbial risk assessments and future regulations of manure utilization.

Self‐contamination during doffing of personal protective equipment (PPE) is a concern for healthcare workers (HCW) following SARS‐CoV‐2‐positive patient care. Staff may subconsciously become contaminated through improper glove removal; so, quantifying this exposure is critical for safe working procedures. HCW surface contact sequences on a respiratory ward were modeled using a discrete‐time Markov chain for: IV‐drip care, blood pressure monitoring, and doctors' rounds. Accretion of viral RNA on gloves during care was modeled using a stochastic recurrence relation. In the simulation, the HCW then doffed PPE and contaminated themselves in a fraction of cases based on increasing caseload. A parametric study was conducted to analyze the effect of: (1a) increasing patient numbers on the ward, (1b) the proportion of COVID‐19 cases, (2) the length of a shift, and (3) the probability of touching contaminated PPE. The driving factors for the exposure were surface contamination and the number of surface contacts. The results simulate generally low viral exposures in most of the scenarios considered including on 100% COVID‐19 positive wards, although this is where the highest self‐inoculated dose is likely to occur with median 0.0305 viruses (95% CI =0–0.6 viruses). Dose correlates highly with surface contamination showing that this can be a determining factor for the exposure. The infection risk resulting from the exposure is challenging to estimate, as it will be influenced by the factors such as virus variant and vaccination rates. [ABSTRACT FROM AUTHOR]

Knowledge gaps in the exposure parameters for recreational water activities make quantitative risk assessment related to water recreation difficult. Therefore, the annual exposure frequency and single exposure duration for the recreational water activities of residents from ten cities in the North and South of China were investigated. Questionnaire interviews were carried on recreational water activities comprising swimming (SW), boating (BA), playing in interactive fountains (PF), and watching fountains (WF). Quantitative microbial risk assessment for the exposure of urban residents to Cryptosporidium and Giardia was also performed. For the four recreational water activities, the participation rates of urban residents in SW and WF were higher than the others. For SW and BA, the mean annual exposure frequency and single exposure duration for males were significantly higher than those for females. PF and WF showed the opposite. The annual exposure frequency for above 35-year-old residents was higher than that for young residents (18–35 years). However, the single exposure duration for young residents was highest in SW, BA, and PF. The mean annual exposure frequency and single exposure duration for North China residents were higher than those for South China residents in all recreational water activities, except for SW. Overall, the annual exposure frequency and single exposure duration in recreational water activities for all urban residents followed a lognormal distribution. In the four recreational water activities, the total annual infection risk of male exposure to Cryptosporidium was 1.0 × 10-2, with the confidence intervals between 95 and 5% of [4.3 × 10-4, 3.7 × 10-2], whereas that for females was 6.8 × 10-3 and [4.2 × 10-4, 2.4 × 10-2]. Also, the annual infection risk of males to Giardia was 8.8 × 10-3 and [5.1×10-4, 3.2×10-2], and that of females was 5.3 × 10-3 and [4.0 × 10-4, 1.8 × 10-2]. These results demonstrated that SW and PF made the highest contribution to the total annual infection risk. Sensitivity analysis highlighted that the characterization of exposure parameters plays a critical role in health risk assessment, which may provide a scientific basis for recreational water quality standards formulation. [ABSTRACT FROM AUTHOR]