Assessment of the risks for human health of adenoviruses, hepatitis A virus, rotaviruses and enteroviruses in the Buffalo River and three source water dams in the Eastern Cape

Quantifying health risks from wastewater reclamation and agricultural reuse using life cycle assessment and quantitative microbial risk assessment

To mitigate the scarcity of freshwater resources, humans have increasingly reused treated wastewater for various purposes, with irrigation accounting for over 70 % of daily water consumption. While wastewater reuse offers a sustainable solution for conserving potable and non-potable water, the reclamation and reuse processes can have environmental and health implications, including greenhouse gas emissions, energy consumption, and pathogen exposure. Life cycle assessment (LCA) has been employed to assess the midpoint and endpoint level impacts, such as human disease burden. Likewise, quantitative microbial risk assessment (QMRA) is a valuable tool for evaluating local risks, such as pathogen exposures during irrigation. Both the LCA (to quantify endpoint indicators of the human burden) and the QMRA tool (to quantify disease burden on human health) use a common metric, disability-adjusted life years (i.e., DALY), which is a measure of overall disease burden that represents the number of years lost due to ill-health, disability, or early death as per person per year (DALYpppy). By combining LCA and QMRA, we can quantitatively measure the health risks associated with wastewater reclamation and reuse. This study aims to estimate the accumulated health burden attributed to the operation of an anoxic/anoxic/oxic/oxic wastewater treatment process and the subsequent reuse of treated wastewater for agricultural irrigation, using the disability-adjusted life years (DALYs). Our findings indicate that the treatment operations contribute a global human health burden of 8.08×10-7 DALYs per person per year (DALYpppy), while pathogen exposures during irrigation with treated wastewater pose a local health impact of 2.40×10-2 DALYpppy, emphasizing the importance of wastewater disinfection for reuse.

Changing climate and socio-economic conditions as part of quantitative microbial risk assessment of surface drinking water sources: a review

Climate and socio-economic changes are expected to significantly impact waterborne pathogens and associated health risks, yet the full extent of these effects remains unclear. Accurate quantification of these risks is crucial for informing effective interventions and policy decisions. Quantitative microbial risk assessment (QMRA) serves as a valuable tool for estimating the risk of infection caused by microorganisms in drinking water. This study reviews existing QMRA studies and tools in the context of surface water and drinking water provision. Most studies have implemented various steps of the QMRA framework but often without the application of specific QMRA tools. Although several QMRA tools address climatic factors, there are currently no tools that integrate socio-economic factors into their risk assessments. This study proposes an approach for incorporating both climatic and socio-economic factors into QMRA tools. Specifically, we suggest enhancements to the Swedish QMRA tool - an open-source tool that currently does not incorporate climate and socio-economic changes. Our proposed advancements aim to systematically account for future climatic and socio-economic impacts on health risks, providing a more comprehensive microbial risk assessment tool. These recommendations are also applicable to other QMRA tools, offering a pathway for their development and improving the overall assessment of microbial health risks.

A comprehensive review on human enteric viruses in water: Detection methods, occurrence, and microbial risk assessment

Human enteric viruses, such as norovirus, adenovirus, rotavirus, and enterovirus, are crucial targets in controlling biological contamination in water systems worldwide. Due to their small size and low concentrations in water, effective virus concentration and detection methods are essential for ensuring microbial safety. This paper reviews the typical and innovative methods for concentrating and detecting human enteric viruses, highlights viral contamination levels across different water bodies, and discusses the removal efficiencies of virus through various treatment technologies. The application and current gaps of quantitative microbial risk assessment (QMRA) for evaluating the risks of human enteric viruses is also explored. Innovative methods such as digital polymerase chain reaction and isothermal amplification show promise in sensitivity and convenience, however, distinguishing between infectious and non-infectious viruses should be a key focus of future detection techniques. The highest concentrations of human enteric viruses were detected in wastewater, ranging from 103 to 106 copies/L, while drinking water showed significantly lower concentrations, often below 102 copies/L. QMRA studies suggest that exposure to human enteric viruses, whether through contaminated drinking water, occupational contact, or accidental wastewater discharge, could result in a life expectancy of 1.96 × 10-4 to 4.53 × 10-1 days/year.

Seasonal assessment of risks to canoeists' health in a Taiwanese recreational river

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.

Health risk assessment of swimming beaches microbial contamination: a case study - Mahmoudabad, Iran

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.

Microbial health risks associated with rotavirus and enteric bacteria in River Ala in Akure, Nigeria

AIM

This study was carried out to determine the microbial health risks associated with a surface water commonly used for bathing, drinking, domestic and irrigational activities in Akure, Nigeria.

METHODS AND RESULTS

Water samples were collected from the river from March to June, 2018. The load of enteric bacteria, somatic coliphages and rotavirus in the water samples were determined using culture-based methods and molecular technique. The physicochemical characteristics of the water samples were determined using standard methods. The risks of rotavirus, Salmonella and Shigella infections resulting from ingestion of the water from the river were estimated using dose-response model. Redundancy analysis revealed that the levels of E. coli and Salmonella were highly associated with salinity and turbidity. The risks of infection associated with rotavirus (3.3 × 10^-3 ) was higher than those associated with Salmonella (1.3 × 10^-4 ) and Shigella (1.3 × 10^-3 ), and were all above the WHO acceptable risk limit (10^-4 ).

CONCLUSION

Accidental or intentional ingestion of water from the river may pose potential risks of gastrointestinal illness to humans.

SIGNIFICANCE AND IMPACT OF STUDY

Quantitative microbial risk assessment is essential in establishing adequate water management practices that must be strictly followed in order to protect human health.

Metagenomic Analysis of Viral Community in the Yangtze River Expands Known Eukaryotic and Prokaryotic Virus Diversity in Freshwater

Viruses in aquatic ecosystems are characterized by extraordinary abundance and diversity. Thus far, there have been limited studies focused on viral communities in river water systems. Here, we investigated the virome of the Yangtze River Delta using viral metagenomic analysis. The compositions of viral communities from six sampling sites were analyzed and compared. By using library construction and next generation sequencing, contigs and singlet reads similar to viral sequences were classified into 17 viral families, including nine dsDNA viral families, four ssDNA viral families and four RNA viral families. Statistical analysis using Friedman test suggested that there was no significant difference among the six sampling sites (P ​> ​0.05). The viromes in this study were all dominated by the order Caudovirales, and a group of Freshwater phage uvFW species were particularly prevalent among all the samples. The virome from Nanjing presented a unique pattern of viral community composition with a relatively high abundance of family Parvoviridae. Phylogenetic analyses based on virus hallmark genes showed that the Caudovirales order and CRESS-DNA viruses presented high genetic diversity, while viruses in the Microviridae and Parvoviridae families and the Riboviria realm were relatively conservative. Our study provides the first insight into viral community composition in large river ecosystem, revealing the diversity and stability of river water virome, contributing to the proper utilization of freshwater resource.

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First insight into viral community composition in large river ecosystem.

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Virus hallmark genes present both diverse and conservative characteristics.

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The composition of viral communities is similar on the whole.

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Slight regional variation of virome is existed in individual areas.

Human Fecal Pollution Monitoring and Microbial Risk Assessment for Water Reuse Potential in a Coastal Industrial-Residential Mixed-Use Watershed

Rapid economic development has caused industrial expansion into residential communities, leading to higher fecal pollution loads that could be discharged into aquatic environments. However, little is known regarding the potential microbial impact on human health. This study investigated microbial contamination from coastal industrial–residential community areas in nine sampling sites in waterways during three dry events. A general microbial source tracking (MST) marker, GenBac3, was detected in all samples from all three events, indicating continuing fecal pollution in the area, mostly from human sewage contamination. This was shown by the human-specific genetic marker crAssphage (88.9%) and human polyomavirus (HPyVs; 92.6%) detection. Enteric human adenovirus (HAdV40/41) showed three positive results only from residential sites in the first event. No spatial difference was observed for MST markers and traditional fecal indicators (total coliforms and Escherichia coli) in each event. Still, a significantly lower abundance of GenBac3, HPyVs, and total coliforms in the first sampling event was detected. Spearman’s rho analysis indicated a strong correlation among certain pairs of microbial parameters. Multivariate analysis revealed two clusters of samples separated by land use type (industrial vs. residential). According to factor analysis of mixed data, the land use parameter was more associated with physicochemical parameters (i.e., salinity, conductivity, water temperature, and dissolved oxygen). A Quantitative Microbial Risk Assessment (QMRA) was then conducted to estimate the annual infection risks of HAdV40/41 for non-potable water reuse purposes using predicted concentrations from crAssphage and HPyVs. The highest risks (95th percentiles) were ranked by food crop irrigation, aquaculture, and toilet flushing, at 10^–1, 10^–2, and 10^–3 per person per year (pppy). Required treatment levels to achieve a 10^–4 pppy annual infection risk were estimated. QMRA-based water treatment scenarios were suggested, including chlorination for toilet flushing reuse and depth filtration prior to chlorination for aquaculture and food crop irrigation. Microbial monitoring combined with a QMRA could provide better insights into fecal pollution patterns and the associated risks, facilitating effective water quality management and appropriate prior treatments for water reuse.

Navigating Data Uncertainty and Modeling Assumptions in Quantitative Microbial Risk Assessment in an Informal Settlement in Kampala, Uganda

Decision-makers in developing communities often lack credible data to inform decisions related to water, sanitation, and hygiene. Quantitative microbial risk assessment (QMRA), which quantifies pathogen-related health risks across exposure routes, can be informative; however, the utility of QMRA for decision-making is often undermined by data gaps. This work integrates QMRA, uncertainty and sensitivity analyses, and household surveys in Bwaise, Kampala (Uganda) to characterize the implications of censored data management, identify sources of uncertainty, and incorporate risk perceptions to improve the suitability of QMRA for informal settlements or similar settings. In Bwaise, drinking water, hand rinse, and soil samples were collected from 45 households and supplemented with data from 844 surveys. Quantified pathogen (adenovirus, Campylobacter jejuni, and Shigella spp./EIEC) concentrations were used with QMRA to model infection risks from exposure through drinking water, hand-to-mouth contact, and soil ingestion. Health risks were most sensitive to pathogen data, hand-to-mouth contact frequency, and dose-response models (particularly C. jejuni). When managing censored data, results from upper limits of detection, half of limits of detection, and uniform distributions returned similar results, which deviated from lower limits of detection and maximum likelihood estimation imputation approaches. Finally, risk perceptions (e.g., it is unsafe to drink directly from a water source) were identified to inform risk management.

Proposal of a pathway for enteric virus groups detection as indicators of faecal contamination to enhance the evaluation of microbiological quality in freshwater in Argentina

An environmental survey was conducted in order to assess the frequency of detection of picobirnavirus (PBV), human adenovirus (HAdV) and infective enterovirus (iEV) as indicators of faecal contamination in freshwater, and to determine their potential as reporters of the presence of other enteric viruses, such as group A rotavirus (RVA). The study was carried out over a three-year period (2013-2015) in the San Roque Dam, Córdoba, Argentina. The overall frequency detection was 62.9% for PBV, 64.2% for HAdV and 70.4% for iEV. No significant differences were observed in the rates of detection for any of these viruses through the years studied, and a seasonal pattern was not present. Whenever there was RVA detection in the samples analyzed, there was also detection of iEV and/or HAdV and/or PBV. At least one of the viral groups analyzed was demonstrated in the 100% of the samples with faecal coliforms values within the guideline limits. In this setting, especially in those samples which reveal faecal indicator bacteria within the guideline limit, we propose to carry out a pathway, involving PBV, HAdV and iEV detection in order to enhance the evaluation of microbiological quality in freshwater in Argentina. The proposed methodological strategy could report faecal contamination in water, mainly of human origin, and the condition of the matrix to maintain viral viability. In addition, the viral groups selected could report the presence of RV.

Occurrence of Human Enteric Viruses in Water Sources and Shellfish: A Focus on Africa

Enteric viruses are a diverse group of human pathogens which are primarily transmitted by the faecal-oral route and are a major cause of non-bacterial diarrhoeal disease in both developed and developing countries. Because they are shed in high numbers by infected individuals and can persist for a long time in the environment, they pose a serious threat to human health globally. Enteric viruses end up in the environment mainly through discharge or leakage of raw or inadequately treated sewage into water sources such as springs, rivers, dams, or marine estuaries. Human exposure then follows when contaminated water is used for drinking, cooking, or recreation and, importantly, when filter-feeding bivalve shellfish are consumed. The human health hazard posed by enteric viruses is particularly serious in Africa where rapid urbanisation in a relatively short period of time has led to the expansion of informal settlements with poor sanitation and failing or non-existent wastewater treatment infrastructure, and where rural communities with limited or no access to municipal water are dependent on nearby open water sources for their subsistence. The role of sewage-contaminated water and bivalve shellfish as vehicles for transmission of enteric viruses is well documented but, to our knowledge, has not been comprehensively reviewed in the African context. Here we provide an overview of enteric viruses and then review the growing body of research where these viruses have been detected in association with sewage-contaminated water or food in several African countries. These studies highlight the need for more research into the prevalence, molecular epidemiology and circulation of these viruses in Africa, as well as for development and application of innovative wastewater treatment approaches to reduce environmental pollution and its impact on human health on the continent.

Assessment of socioeconomic inequality based on virus-contaminated water usage in developing countries: A review

Water is an essential resource required for various human activities such as drinking, cooking, and other recreational activities. While developed nations have made significant improvement in providing adequate quality water and sanitation devoid of virus contaminations to a significant percentage of the residences, many of the developing countries are still lacking in these regards, leading to many death cases among the vulnerable due to ingestion of virus-contaminated water and other waterborne pathogens. However, the recent global pandemic of COVID-19 seems to have changed the paradigm by reawakening the importance of water quality and sanitation, and focusing more attention on the pervasive effect of the use of virus-contaminated water as it can be a potential driver for the spread of the virus and other waterborne diseases, especially in developing nations that are characterized by low socioeconomic development. Therefore, this review assessed the socioeconomic inequalities related to the usage of virus-contaminated water and other waterborne pathogens in developing countries. The socioeconomic factors attributed to the various waterborne diseases due to the use of virus-contaminated water in many developing countries are poverty, the standard of living, access to health care facilities, age, gender, and level of education. Some mitigation strategies to address the viral contamination of water sources are therefore proposed, while future scope and recommendations on tackling the essential issues related to socioeconomic inequality in developing nations are highlighted.

Assessment of socioeconomic inequality based on virus-contaminated water usage in developing countries: A review

Water is an essential resource required for various human activities such as drinking, cooking, and other recreational activities. While developed nations have made significant improvement in providing adequate quality water and sanitation devoid of virus contaminations to a significant percentage of the residences, many of the developing countries are still lacking in these regards, leading to many death cases among the vulnerable due to ingestion of virus-contaminated water and other waterborne pathogens. However, the recent global pandemic of COVID-19 seems to have changed the paradigm by reawakening the importance of water quality and sanitation, and focusing more attention on the pervasive effect of the use of virus-contaminated water as it can be a potential driver for the spread of the virus and other waterborne diseases, especially in developing nations that are characterized by low socioeconomic development. Therefore, this review assessed the socioeconomic inequalities related to the usage of virus-contaminated water and other waterborne pathogens in developing countries. The socioeconomic factors attributed to the various waterborne diseases due to the use of virus-contaminated water in many developing countries are poverty, the standard of living, access to health care facilities, age, gender, and level of education. Some mitigation strategies to address the viral contamination of water sources are therefore proposed, while future scope and recommendations on tackling the essential issues related to socioeconomic inequality in developing nations are highlighted.

A Data Simulation Method to Optimize a Mechanistic Dose-Response Model for Viral Loads of Hepatitis A

Driven by the quantitative estimate of risk via the dose-response models, quantitative microbial risk assessment has been used successfully for public health interventions. The dose-response models are derived starting from an average exposed dose of infectious particles, this dictates the of dose data units required. Then dose-response data from animal model experiments are used to optimize these mechanistic dose-response models. For hepatitis A (Hep-A), the only available dose-response data use grams of feces for dose units. Therefore, to develop a dose-response model for Hep-A a method of converting these doses in grams of feces into infectious particles, while accounting for the uncertainty of this conversion is needed. This research develops a method to couple data simulation with the likelihood estimation method for model optimization to accomplish this. This adapted method uses data simulation to model the doses as viral particles while accounting for the within-group variability of this simulation. Then these simulated doses, coupled with the original dose-response data, are used to optimize the mechanistic dose-response models. This method results in a more computationally rigorous means of modeling these types of dose-response data. The resulting dose-response model for Hep-A is also more appropriate to use than the current option for Hep-A risk models.

Quantifying public health risks from exposure to waterborne pathogens during river bathing as a basis for reduction of disease burden

A Quantitative Microbial Risk Assessment (QMRA) technique was applied to assess the public health risk from exposure to infectious microorganisms at bathing areas of three rivers in Bangladesh. The QMRA assessed the probability of illness due to the accidental ingestion of river water impacted by untreated sewage. The simplified QMRA was based on average concentrations of four reference pathogens Escherichia coli (E. coli) O157:H7, Cryptosporidium spp, norovirus and rotavirus relative to indicator bacterium E. coli. Public health risk was estimated as the probability of infection and illness from a single exposure of bathers. The risks of illness were ranged from 7 to 10% for E. coli O157:H7, 13 to 19% for Cryptosporidium, 7 to 10% for norovirus and 12 to 17% for rotavirus. The overall risk of illness at the rivers was slightly higher in children (9-19%) compared to adults (7-16%). The risks of illness in individuals exposed to the river bathing were unacceptably high, exceeding the USEPA acceptable risk of 3-6 illnesses per hundred bathing events. This study gives a basis for reducing the burden of disease in the population by applying appropriate risk management. Findings and methods of this study will be helpful for other countries with similar socio-economic and geographic settings.

Detection, Quantification, and Microbial Risk Assessment of Group A Rotavirus in Rivers from Uruguay

The aim of this study was to detect, quantify, and assess the risk of infection and illness for Group A Rotavirus (RVA) in the watersheds of the Santa Lucia and Uruguay rivers in Uruguay. Monthly sampling was carried out for one year in six sites in the watershed of the Santa Lucía River and four in the Uruguay River. All the collection sites are used for recreational activities. Viral concentration was performed with the adsorption-elution method, and detection and quantification of RVA was carried out by TaqMan quantitative PCR (qPCR). Quantitative microbial risk assessment was applied to estimate the daily and annual risk of RVA infection, as well as the daily risk of illness considering direct exposure through recreational activity. RVA was detected in 42% (20/48) of the analyzed samples in the Uruguay River and 40% (29/72) in the Santa Lucía River. The virus was present in all the analyzed points in both watersheds. A pattern of seasonality, characterized by a higher detection frequency of the virus during coldest month of the year, was observed in both basins. The mean concentration for RVA was 1.3 × 10⁵ genomic copies/L. The microbiological risk assessment shows that Santa Lucía watershed presented the highest daily risk of infection (6.41E-01) and illness (3.20E-01) estimated for the point downstream of Florida City; meanwhile for Uruguay River, the highest probabilities of infection (6.82E-01) and illness (3.41E-01) were estimated for the collection site for drinking water intake in Salto city. These results suggest that RVA contamination of these important rivers negatively impact on their microbiological quality since they are used for recreation and drinking water intake, demonstrating that the disposal of waste from cities located in their riverside confers a constant threat of infection for the general population, especially for children.

Environmental and Adaptive Changes Necessitate a Paradigm Shift for Indicators of Fecal Contamination

Changes in the occurrence, distribution, and seasonal variation of waterborne pathogens due to global climate change may increase the risk of human exposure to these microorganisms, thus heightening the need for more reliable surveillance systems. Routine monitoring of drinking water supplies and recreational waters is performed using fecal indicator microorganisms, such as Escherichia coli , Enterococcus spp., and coliphages. However, the presence and numbers of these indicators, especially E. coli and Enterococcus spp., do not correlate well with those of other pathogens, especially enteric viruses, which are a major cause of waterborne outbreaks associated with contaminated water and food, and recreational use of lakes, ponds, rivers, and estuarine waters. For that reason, there is a growing need for a surveillance system that can detect and quantify viral pathogens directly in water sources to reduce transmission of pathogens associated with fecal transmission. In this review, we present an updated overview of relevant waterborne enteric viruses that we believe should be more commonly screened to better evaluate water quality and to determine the safety of water use and reuse and of epidemiological data on viral outbreaks. We also discuss current methodologies that are available to detect and quantify these viruses in water resources. Finally, we highlight challenges associated with virus monitoring. The information presented in this review is intended to aid in the assessment of human health risks due to contact with water sources, especially since current environmental and adaptive changes may be creating the need for a paradigm shift for indicators of fecal contamination.

Quantitative PCR Detection of Enteric Viruses in Wastewater and Environmental Water Sources by the Lisbon Municipality: A Case Study

Current regulations and legislation require critical revision to determine safety for alternative water sources and water reuse as part of the solution to global water crisis. In order to fulfill those demands, Lisbon municipality decided to start water reuse as part of a sustainable hydric resources management, and there was a need to confirm safety and safeguard for public health for its use in this context. For this purpose, a study was designed that included a total of 88 samples collected from drinking, superficial, underground water, and wastewater at three different treatment stages. Quantitative Polimerase Chain Reaction (PCR) detection (qPCR) of enteric viruses Norovirus (NoV) genogroups I (GI) and II (GII) and Hepatitis A (HepA) was performed, and also FIB (E. coli, enterococci and fecal coliforms) concentrations were assessed. HepA virus was only detected in one untreated influent sample, whereas NoV GI/ NoV GI were detected in untreated wastewater (100/100%), secondary treated effluent (47/73%), and tertiary treated effluent (33/20%). Our study proposes that NoV GI and GII should be further studied to provide the support that they may be suitable indicators for water quality monitoring targeting wastewater treatment efficiency, regardless of the level of treatment.

Quantitative Microbial Risk Assessment and Infectious Disease Transmission Modeling of Waterborne Enteric Pathogens

PURPOSE OF REVIEW

Waterborne enteric pathogens remain a global health threat. Increasingly, quantitative microbial risk assessment (QMRA) and infectious disease transmission modeling (IDTM) are used to assess waterborne pathogen risks and evaluate mitigation. These modeling efforts, however, have largely been conducted independently for different purposes and in different settings. In this review, we examine the settings where each modeling strategy is employed.

RECENT FINDINGS

QMRA research has focused on food contamination and recreational water in high-income countries (HICs) and drinking water and wastewater in low- and middle-income countries (LMICs). IDTM research has focused on large outbreaks (predominately LMICs) and vaccine-preventable diseases (LMICs and HICs). Human ecology determines the niches that pathogens exploit, leading researchers to focus on different risk assessment research strategies in different settings. To enhance risk modeling, QMRA and IDTM approaches should be integrated to include dynamics of pathogens in the environment and pathogen transmission through populations.

Human mastadenovirus in water, sediment, sea surface microlayer, and bivalve mollusk from southern Brazilian beaches

Anthropogenic contamination of beaches in the south of Brazil was assessed by detection of Escherichia coli, human mastadenovirus species C (HAdV-C) and F (HAdV-F) and hepatitis E virus (HEV). Sampling was carried out in October (2016), and in January, April and July (2017). Water, sediment, sea surface microlayer (SML), bivalves, and air sentinel samples were evaluated. Quantitative microbiological risk assessment (QMRA) was used to estimate the probability of swimmer infection. HAdV-C was present in 26% of the samples, for both qPCR and viral isolation. The highest rates of detection in genomic copies (GC) were in water (2.42E+10 GC/L), SML (2.08E+10 GC/L), sediment (3.82E+08 GC/g) and bivalves (3.91E+07 GC/g). QMRA estimated daily and annual risks with a maximum value (9.99E-01) in almost all of the samples. Viable HAdV-C was often detected in the SML, pointing that this is a source of infection for people bathing in these waters.

The landscape of enteric pathogen exposure of young children in public domains of low-income, urban Kenya: The influence of exposure pathway and spatial range of play on multi-pathogen exposure risks

Young children are infected by a diverse variety of enteric pathogens in low-income, high-burden countries. Little is known about which conditions pose the greatest risk for enteric pathogen exposure and infection. Young children frequently play in residential public areas around their household, including areas contaminated by human and animal feces, suggesting these exposures are particularly hazardous. The objective of this study was to examine how the dose of six types of common enteric pathogens, and the probability of exposure to one or multiple enteric pathogens for young children playing at public play areas in Kisumu, Kenya is influenced by the type and frequency of child play behaviors that result in ingestion of soil or surface water. Additionally, we examine how pathogen doses and multi-pathogen exposure are modified by spatial variability in the number of public areas children are exposed to in their neighborhood. A Bayesian framework was employed to obtain the posterior distribution of pathogen doses for a certain number of contacts. First, a multivariate mixed effects tobit model was used to obtain the posterior distribution of pathogen concentrations, and their interdependencies, in soil and surface water, based upon empirical data of enteric pathogen contamination in three neighborhoods of Kisumu. Then, exposure doses were estimated using behavioral contact parameters from previous studies and contrasted under different exposure conditions. Pathogen presence and concentration in soil varied widely across local (< 25 meter radius area) and neighborhood-level scales, but pathogens were correlated among distinct surface water samples collected near to each other. Multi-pathogen exposure of children at public play areas was common. Pathogen doses and the probability of multi-pathogen ingestion increased with: higher frequency of environmental contact, especially for surface water; larger volume of soil or water ingested; and with play at multiple sites in the neighborhood versus single site play. Child contact with surface water and soil at public play areas in their neighborhood is an important cause of exposure to enteric pathogens in Kisumu, and behavioral, environmental, and spatial conditions are determinants of exposure.

Microbial risk assessment in recreational freshwaters from southern Brazil

In this study, total coliforms (TC), Escherichia coli, enterovirus (EV), rotavirus (RV), and human mastadenovirus species C and F (HAdV-C and HAdV-F) were evaluated in water samples from Belo Stream. For HAdV-C and F, the infectivity was assessed by integrated cell culture quantitative real-time polymerase chain reaction (ICC-qPCR). Samples were collected monthly (May/2015 to April/2016) at four sites. Viral analyses were performed for both ultracentrifuge-concentrated and unconcentrated samples. For site P4 (used for recreational purposes), QMRA was applied to estimate health risks associated with exposure to E. coli and HAdV-C and F. TC and E. coli were present throughout the collection period. EV and RV were not detected. HAdV-C were present in 8.51% (1.89E + 06 to 2.28E + 07 GC (Genomic Copies)/L) and 21.27% (2.36E + 05 to 1.29E + 07 GC/L) for unconcentrated and concentrated samples, respectively. For HAdV-F were 12.76% (2.77E + 07 to 3.31E + 08 GC/L) and 48.93% (1.10E + 05 to 4.50E + 08 GC/L) for unconcentrated and concentrated samples, respectively. For unconcentrated samples, infectivity for HAdV-C was detected in 37.20% (1st ICC-qPCR) and 25.58% (2nd ICC-qPCR). For HAdV-F, infectivity was detected in 6.97% (1st ICC-qPCR) and 6.97% (2nd ICC-qPCR). For concentrated samples, HAdV-C infectious was observed in 17.02% (1st ICC-qPCR) and in 8.51% (2nd ICC-qPCR). For HAdV-F, were present in 8.51% for both 1st and 2nd ICC-qPCR. Statistical analyzes showed significant difference between the collection sites when analyzed the molecular data of HAdV-F, data of TC and E. coli. Correlation tests showed direct correlation between HAdV-F with E. coli and TC. E. coli concentrations translated to the lowest estimates of infection risks (8.58E-05 to 2.17E-03). HAdV-F concentrations were associated with the highest infection risks at 9.99E-01 and for group C, 1.29E-01 to 9.99E-01. These results show that commonly used bacterial indicators for water quality may not infer health risks associated with viruses in recreational freshwaters.

Spatial dynamic assessment of health risks for urban river cruises

River cruising ships move along river courses, and thus health risks to passengers may vary spatially due to the accidental exposure of river fecal pollution. This study performed a spatial dynamic assessment of health risks for river cruises in the highly urbanized Tamsui River Basin. First, the spatial distributions of river Escherichia coli (E. coli) were probabilistically characterized using indicator kriging (IK). Moreover, the current river cruise information was surveyed to obtain cruise routes and transit times. Then, to explore the parametric uncertainty of quantitative microbial risk assessment (QMRA), the ingestion rate (IR) for boating was determined using Monte Carlo simulation (MCS). Moreover, river E. coli distributions were estimated using nonparametric MCS according to multi-threshold IK estimates. Eventually, after combining the distribution of the joint probability of the IR and E. coli in QMRA, the β-Poisson dose-response function was adopted to analyze risks to river cruise passengers at discretized segments of cruise routes. Health risks to river cruise passengers were integrated at the discretized segments to explore suitable recreational strategies for river cruises. The research results indicate that all health risks do not exceed a daily target level of 8 illnesses per 1000 exposures for single-trip cruise routes. However, health risks to passengers can exceed this level for round-trip cruise routes along highly polluted urban river courses.

Overview of Trends in the Application of Metagenomic Techniques in the Analysis of Human Enteric Viral Diversity in Africa's Environmental Regimes

There has been an increase in the quest for metagenomics as an approach for the identification and study of the diversity of human viruses found in aquatic systems, both for their role as waterborne pathogens and as water quality indicators. In the last few years, environmental viral metagenomics has grown significantly and has enabled the identification, diversity and entire genome sequencing of viruses in environmental and clinical samples extensively. Prior to the arrival of metagenomics, traditional molecular procedures such as the polymerase chain reaction (PCR) and sequencing, were mostly used to identify and classify enteric viral species in different environmental milieu. After the advent of metagenomics, more detailed reports have emerged about the important waterborne viruses identified in wastewater treatment plant effluents and surface water. This paper provides a review of methods that have been used for the concentration, detection and identification of viral species from different environmental matrices. The review also takes into consideration where metagenomics has been explored in different African countries, as well as the limitations and challenges facing the approach. Procedures including sample processing, experimental design, sequencing technology, and bioinformatics analysis are discussed. The review concludes by summarising the current thinking and practices in the field and lays bare key issues that those venturing into this field need to consider and address.

Quantitative microbial risk assessment of microbial source tracking markers in recreational water contaminated with fresh untreated and secondary treated sewage

Microbial source tracking (MST) methods have provided the means to identify sewage contamination in recreational waters, but the risk associated with elevated levels of MST targets such as sewage-associated Bacteroides HF183 and other markers is uncertain. Quantitative microbial risk assessment (QMRA) modeling allows interpretation of MST data in the context of the risk of gastrointestinal (GI) illness caused by exposure to pathogens. In this study, five sewage-associated, quantitative PCR (qPCR) MST markers [Bacteroides HF183 (HF183), Methanobrevibacter smithii nifH (nifH), human adenovirus (HAdV), human polyomavirus (HPyV) and pepper mild mottle virus (PMMoV)] were evaluated to determine at what concentration these nucleic acid markers reflected a significant health risk from exposure to fresh untreated or secondary treated sewage in beach water. The QMRA models were evaluated for a target probability of illness of 36 GI illnesses/1000 swimming events (i.e., risk benchmark 0.036) for the reference pathogens norovirus (NoV) and human adenovirus 40/41 (HAdV 40/41). Sewage markers at several dilutions exceeded the risk benchmark for reference pathogens NoV and HAdV 40/41. HF183 concentrations 3.22 × 10³ (for both NoV and HAdV 40/41) gene copies (GC)/100 mL of water contaminated with fresh untreated sewage represented risk >0.036. Similarly, HF183 concentrations 3.66 × 10³ (for NoV and HAdV 40/41) GC/100 mL of water contaminated with secondary treated sewage represented risk >0.036. HAdV concentration as low as 4.11 × 10¹ GC/100 mL of water represented risk >0.036 when water was contaminated with secondary treated sewage. Results of this study provide a valuable context for water quality managers to evaluate human health risks associated with contamination from fresh sewage. The approach described here may also be useful in the future for evaluating health risks from contamination with aged or treated sewage or feces from other animal sources as more data are made available.

Quantitative Microbial Risk Assessment for Workers Exposed to Bioaerosol in Wastewater Treatment Plants Aimed at the Choice and Setup of Safety Measures

Biological risk assessment in occupational settings currently is based on either qualitative or semiquantitative analysis. In this study, a quantitative microbial risk assessment (QMRA) has been applied to estimate the human adenovirus (HAdV) health risk due to bioaerosol exposure in a wastewater treatment plant (WWTP). A stochastic QMRA model was developed considering HAdV as the index pathogen, using its concentrations in different areas and published dose–response relationship for inhalation. A sensitivity analysis was employed to examine the impact of input parameters on health risk. The QMRA estimated a higher average risk in sewage influent and biological oxidation tanks (15.64% and 12.73% for an exposure of 3 min). Sensitivity analysis indicated HAdV concentration as a predominant factor in the estimated risk. QMRA results were used to calculate the exposure limits considering four different risk levels (one illness case per 100, 1.000, 10.000, and 100.000 workers): for 3 min exposures, we obtained 565, 170, 54, and 6 GC/m³ of HAdV. We also calculated the maximum time of exposure for each level for different areas. Our findings can be useful to better define the effectiveness of control measures, which would thus reduce the virus concentration or the exposure time.

Characterizing health risks associated with recreational swimming at Taiwanese beaches by using quantitative microbial risk assessment

Taiwan is surrounded by oceans, and therefore numerous pleasure beaches attract millions of tourists annually to participate in recreational swimming activities. However, impaired water quality because of fecal pollution poses a potential threat to the tourists' health. This study probabilistically characterized the health risks associated with recreational swimming engendered by waterborne enterococci at 13 Taiwanese beaches by using quantitative microbial risk assessment. First, data on enterococci concentrations at coastal beaches monitored by the Taiwan Environmental Protection Administration were reproduced using nonparametric Monte Carlo simulation (MCS). The ingestion volumes of recreational swimming based on uniform and gamma distributions were subsequently determined using MCS. Finally, after the distribution combination of the two parameters, the beta-Poisson dose-response function was employed to quantitatively estimate health risks to recreational swimmers. Moreover, various levels of risk to recreational swimmers were classified and spatially mapped to explore feasible recreational and environmental management strategies at the beaches. The study results revealed that although the health risks associated with recreational swimming did not exceed an acceptable benchmark of 0.019 illnesses daily at all beaches, they approached to this benchmark at certain beaches. Beaches with relatively high risks are located in Northwestern Taiwan owing to the current movements.

Quantitative microbial risk assessment to estimate the health risk from exposure to noroviruses in polluted surface water in South Africa

This study assessed the risks posed by noroviruses (NoVs) in surface water used for drinking, domestic, and recreational purposes in South Africa (SA), using a quantitative microbial risk assessment (QMRA) methodology that took a probabilistic approach coupling an exposure assessment with four dose-response models to account for uncertainty. Water samples from three rivers were found to be contaminated with NoV GI (80-1,900 gc/L) and GII (420-9,760 gc/L) leading to risk estimates that were lower for GI than GII. The volume of water consumed and the probabilities of infection were lower for domestic (2.91 × 10^-8 to 5.19 × 10^-1) than drinking water exposures (1.04 × 10^-5 to 7.24 × 10^-1). The annual probabilities of illness varied depending on the type of recreational water exposure with boating (3.91 × 10^-6 to 5.43 × 10^-1) and swimming (6.20 × 10^-6 to 6.42 × 10^-1) being slightly greater than playing next to/in the river (5.30 × 10^-7 to 5.48 × 10^-1). The QMRA was sensitive to the choice of dose-response model. The risk of NoV infection or illness from contaminated surface water is extremely high in SA, especially for lower socioeconomic individuals, but is similar to reported risks from limited international studies.

Racial differences in seroprevalence of HAV and HEV in blood donors in the Western Cape, South Africa: a clue to the predominant HEV genotype?

Hepatitis E virus (HEV) infection is a major cause of acute hepatitis worldwide. This infection causes major water-borne outbreaks in low- and middle-income countries, whilst in industrialised countries this infection is zoonotic. These differences in epidemiology are related to different HEV genotypes. HEV genotype 3 is a zoonotic infection, whilst genotype 2 causes large outbreaks. This study determined the seroprevalence of HEV in blood donors from the Western Cape. Anti-hepatitis A virus (anti-HAV) antibody was detected in 184/300 (61%) donors. Antibody to HEV (anti-HEV) was detected in 78 of 300 donors (26%). It was highest in mixed race donors (62/100), followed by white donors (23/100) and lowest in black donors (19/100) P = 0.019. Since it is thought that genotypes 1 and 2 predominate both viruses would be acquired by the oro-faecal route, it is surprising that HEV seroprevalence does not mirror that of HAV. We postulate that this may reflect differences in socio-economic status and consumption of dietary meat. So the marked divergence between HEV and HAV seroprevalence may be the result of different routes of transmission. Further data are needed to explore the risk factors associated with HEV infection.

Risk assessment of noroviruses and human adenoviruses in recreational surface waters

In the interest of public health and safety, this study aimed to quantify risks associated with the presence of noroviruses (NoV) and human adenoviruses (HAdV) in an urban catchment area in Singapore. Enteric viruses were quantified using QPCR. NoV were more prevalent in water samples than HAdV, and presented higher associated illness risks across all exposure scenarios. For primary contact recreation of adults and children, mean probability of illness were 0.0061 and 0.0089 for NoV, and 0.0028 and 0.0048 for HAdV. For secondary contact recreation, mean probability of illness were 0.0016 for NoV and 0.00068 for HAdV. Therefore, owing to their prevalence and associated risks, NoV are better suited as reference pathogens in recreational waters in Singapore.

Urban effluent discharges as causes of public and environmental health concerns in South Africa's aquatic milieu

The water quality in South Africa's river systems is rapidly deteriorating as a consequence of increased discharge of wastewater effluents. The natural ability of rivers and reservoirs to trap toxic chemicals and nutrients in their sediments enables these systems to accumulate contaminants, altering the natural balance in environmental water quality, thereby raising a plethora of public and environmental health concerns. Impaired water quality has been linked to an array of problems in South Africa including massive fish mortalities, altered habitat template leading to the thinning of riverine macroinvertebrate diversity, shifts in microbial community structures with drastic ecological consequences and evolvement of antibiotic resistance genes that, under natural conditions, can be transferred to waterborne pathogens. Urban wastewater discharge has also been implicated in increased bioaccumulation of metals in edible plant parts, elevated concentrations of endocrine-disrupting compounds (EDCs), which are blamed for reduced fertility and increased cancer risk, excessive growth of toxic cyanobacteria and an increase in concentrations of pathogenic microorganisms which constitute a potential health threat to humans. However, despite the ecotoxicological hazards posed by wastewater effluents, ecotoxicological studies are currently underutilised in South African aquatic ecosystem assessments, and where they have been done, the observation is that ecotoxicological studies are mostly experimental and restricted to small study areas. More research is still needed to fully assess especially the ecotoxicological consequences of surface water pollution by urban wastewater effluents in South Africa. A review of the effects of urban effluent discharges that include domestic effluent mixed with industrial effluent and/or urban stormwater run-off is hereby presented.

Quantification of Protozoa and Viruses from Small Water Volumes

Large sample volumes are traditionally required for the analysis of waterborne pathogens. The need for large volumes greatly limits the number of samples that can be processed. The aims of this study were to compare extraction and detection procedures for quantifying protozoan parasites and viruses from small volumes of marine water. The intent was to evaluate a logistically simpler method of sample collection and processing that would facilitate direct pathogen measures as part of routine monitoring programs. Samples were collected simultaneously using a bilayer device with protozoa capture by size (top filter) and viruses capture by charge (bottom filter). Protozoan detection technologies utilized for recovery of Cryptosporidium spp. and Giardia spp. were qPCR and the more traditional immunomagnetic separation-IFA-microscopy, while virus (poliovirus) detection was based upon qPCR versus plaque assay. Filters were eluted using reagents consistent with the downstream detection technologies. Results showed higher mean recoveries using traditional detection methods over qPCR for Cryptosporidium (91% vs. 45%) and poliovirus (67% vs. 55%) whereas for Giardia the qPCR-based methods were characterized by higher mean recoveries (41% vs. 28%). Overall mean recoveries are considered high for all detection technologies. Results suggest that simultaneous filtration may be suitable for isolating different classes of pathogens from small marine water volumes. More research is needed to evaluate the suitability of this method for detecting pathogens at low ambient concentration levels.

Recombinant adenovirus as a model to evaluate the efficiency of free chlorine disinfection in filtered water samples

BACKGROUND

In Brazil, ordinance no. 2,914/2011 of the Ministry of Health requires the absence of total coliforms and Escherichia coli (E. coli) in treated water. However it is essential that water treatment is effective against all pathogens. Disinfection in Water Treatment Plants (WTP) is commonly performed with chlorine.

METHODS

The recombinant adenovirus (rAdV), which expresses green fluorescent protein (GFP) when cultivated in HEK 293A cells, was chosen as a model to evaluate the efficiency of chlorine for human adenovirus (HAdV) inactivation in filtered water samples from two WTPs: Lagoa do Peri (pH 6.9) and Morro dos Quadros (pH 6.5). Buffered demand free (BDF) water (pH 6.9 and 8.0) was used as control. The samples were previously submitted to physicochemical characterization, and bacteriological analysis. Two free chlorine concentrations and two temperatures were assayed for all samples (0.2 mg/L, 0.5 mg/L, and 15°C, and 20°C). Fluorescence microscopy (FM) was used to check viral infectivity in vitro and qPCR as a molecular method to determine viral genome copies. Real treated water samples from the WTP (at the output of WTP and the distribution network) were also evaluated for total coliforms, E. coli and HAdV.

RESULTS

The time required to inactivate 4log₁₀ of rAdV was less than 1 min, when analyzed by FM, except for BDF pH 8.0 (up to 2.5 min for 4log₁₀). The pH had a significant influence on the efficiency of disinfection. The qPCR assay was not able to provide information regarding rAdV inactivation. The data were modeled (Chick-Watson), and the observed Ct values were comparable with the values reported in the literature and smaller than the values recommended by the EPA. In the treated water samples, HAdV was detected in the distribution network of the WTP Morro dos Quadros (2.75 × 10(3) PFU/L).

CONCLUSION

The Chick-Watson model proved to have adjusted well to the experimental conditions used, and it was possible to prove that the adenoviruses were rapidly inactivated in the surface water treated with chlorine and that the recombinant adenovirus expressing GFP is a good model for this evaluation.