Published case studies of waterborne disease outbreaks--evidence of a recurrent threat

Integrating consumer risk perception and awareness with simulation-based quantitative microbial risk assessment using a coupled systems framework: A case study of private groundwater users in Ontario

Private well users in Ontario are responsible for ensuring the potability of their own private drinking water source through protective actions (i.e., water treatment, well maintenance, and regular water quality testing). In the absence of regulation and limited surveillance, quantitative microbial risk assessment (QMRA) represents the most practical and robust approach to estimating the human health burden attributable to private wells. For an increasingly accurate estimation, QMRA of private well water should be represented by a coupled model, which includes both the socio-cognitive and physical aspects of private well water contamination and microbial exposure. The objective of the current study was to determine levels of waterborne exposure via well water consumption among three sub-groups (i.e., clusters) of private well users in Ontario and quantify the risk of waterborne acute gastrointestinal illness (AGI) attributed to Giardia, shiga-toxin producing E. coli (STEC) and norovirus from private drinking water sources in Ontario. Baseline simulations were utilized to explore the effect of varying socio-cognitive scenarios on model inputs (i.e., increased awareness, protective actions, aging population). The current study uses a large spatio-temporal groundwater quality dataset and cross-sectional province-wide survey to create socio-cognitive-specific QMRA simulations to estimate the risk of waterborne AGI attributed to three enteric pathogens in private drinking waters source in Ontario. Findings suggest significant differences in the level of exposure among sub-groups of private well users. Private well users within Cluster 3 are characterised by higher levels of exposure and annual illness attributable to STEC, Giardia and norovirus than Clusters 1 and 2. Provincial incidence rates of 520.9 (1522 illness per year), 532.1 (2211 illness per year) and 605.5 (5345 illness per year) cases/100,000 private well users per year were predicted for private well users associated with Clusters 1 through 3. Established models will enable development of necessary tools tailored to specific groups of at-risk well users, allowing for preventative public health management of private groundwater sources.

Assessing the risk of acute gastrointestinal illness attributable to three enteric pathogens from contaminated private water wells in Ontario

The province of Ontario compromises the largest groundwater reliant population in Canada serving approximately 1.6 million individuals. Unlike municipal water systems, private well water is not required to meet water quality regulatory standards and thus source maintenance, treatment and testing remains the responsibility of the well owner. Infections associated with private drinking water systems are rarely documented given their typically sporadic nature, thus the human health effects (e.g., acute gastrointestinal illness (AGI)) on consumers remains relatively unknown, representing a significant gap in water safety management. The current study sought to quantify the risk of waterborne AGI attributed to Giardia, shiga-toxin producing E. coli (STEC) and norovirus from private drinking water sources in Ontario using Monte Carlo simulation-based quantitative microbial risk assessment (QMRA). Findings suggest that consumption of contaminated private well water in Ontario is responsible for approximately 4823 AGI cases annually, with 3464 (71.8%) and 1359 (28.1%) AGI cases predicted to occur in consolidated and unconsolidated aquifers, respectively. By pathogen, waterborne AGI was attributed to norovirus (62%; 2991/4823), Giardia (24.6%; 1186/4823) and STEC (13.4%; 646/4823). The developed QMRA framework was used to assess the potential health impacts of partial and total well water treatment system failure. In the unlikely event of total treatment failure, total mean annual illnesses are predicted to almost double (4217 to 7064 cases per year), highlighting the importance of effective water treatment and comprehensive testing programs in reducing infectious health risks attributable to private well water in Ontario. Study findings indicate significant underreporting of waterborne AGI rates at the provincial level likely biasing public health interventions and programs that are effective in monitoring and minimizing the health risk associated with private well water.

Eco-efficiency analysis of water distribution system flushing into a containment Pond

For a salt or other conservative contaminant contamination event in a water distribution system, opening fire hydrants to flush the system is currently an accepted decontamination method. However, all the contaminated flushed water is discharged to the local surroundings of the fire hydrants and imposes an environmental impact. Another system decontamination alternative can be using a containment pond to catch the contaminated water. To reduce environmental impacts of flushing salt from a water distribution system a comparative life cycle assessment study has been performed for both conventional flushing and for flushing contaminated water into a containment pond. This was performed using SimaPro software for both of these decontamination options and the impacts have been assessed using the IMPACT 2002+ methodology. The results show that environmental impacts can be reduced by 25% for rural areas, 69% for urban roads, 61% for urban lawns, and 64% for mixed land use. In addition, a sensitivity analysis reveals the two most sensitive variables resulting in the finding that a 10% change in the time needed for system decontamination led to a 10% change in environmental impact and a 10% change in the area of land exposed to contaminated water discharge led to an 8% change in environmental impact.

Estimating the duration and overlap of Escherichia coli contamination events in private groundwater supplies for quantitative risk assessment using a multiannual (2010-2017) provincial dataset

Approximately 1.6 million individuals in Ontario rely on private water wells. Private well water quality in Ontario remains the responsibility of the well owner, and due to the absence of regulation, quantitative microbial risk assessment (QMRA) likely represents the most effective approach to estimating and mitigating waterborne infection risk(s) from these supplies. Annual contamination duration (i.e., contaminated days per annum) represents a central input for waterborne QMRA; however, it is typically based on laboratory studies or meta-analyses, thus representing an important limitation for risk assessment, as groundwater mesocosms cannot accurately replicate subsurface conditions. The present study sought to address these limitations using a large spatio-temporal in-situ groundwater quality dataset (>700,000 samples) to evaluate aquifer-specific E. coli die-off rates (CFU/100 mL per day decline), subsequent contamination sequence duration(s) and the likelihood of overlapping contamination events. Findings indicate median E. coli die-off rates of 0.38 CFU/100 mL per day and 0.64 CFU/100 mL per day, for private wells located in unconsolidated and consolidated aquifers, respectlvely, with mean calculated contamination sequence durations of 18 days (unconsolidated) and 11 days (consolidated). Study findings support and permit development of increasingly evidence-based, regionally- and temporally-specific quantitative waterborne risk assessment.

Headwater-to-consumer Drinking Water Security Assessment Framework and Associated Indicators for Small Communities in High-income Countries

Drinking water insecurity in small and rural, remote, or otherwise marginalized communities in Canada is pervasive and complex with multiple dimensions and impacts. These communities face challenges such as variable source water quality, lack of resources, inappropriate treatment technologies, lack of access to training, difficulties retaining qualified personnel, and ineffective governance structures. Currently, there is a gap in the academic literature with respect to drinking water security assessment frameworks or tools for small and rural, remote, or otherwise marginalized communities, particularly in high income countries. Thus, the objective of this study is to introduce a framework for assessing drinking water security, from headwater to consumer, in the context of small and rural, remote, or otherwise marginalized communities.

An indicator-based framework has been developed to evaluate drinking water security, prioritize actions and investments, and support decision-making. The framework builds on expert knowledge and a critical review of security, sustainability, and performance indices of water supply and treatment processes obtained from the literature. The framework is organised into four dimensions of drinking water security from headwaters to consumer: upstream watershed security; source water security; community needs and engagement; and treatment and distribution infrastructure. A list of relevant indicators for each dimension has been compiled to support framework application in a format that is accessible to decision-makers in small and rural, remote, or otherwise marginalized communities.

Surface Water Intrusion, Land Use Impacts, and Bacterial Community Composition in Shallow Groundwater Wells Supplying Potable Water in Sparsely Populated Areas of a Boreal Region

Rural communities often rely on groundwater for potable water supply. In this study, untreated groundwater samples from 28 shallow groundwater wells in Finland (<10 m deep and mostly supplying untreated groundwater to <200 users in rural areas) were assessed for physicochemical water quality, stable water isotopes, microbial water quality indicators, host-specific microbial source tracking (MST) markers, and bacterial community composition, activity, and diversity (using amplicon sequencing of the 16S rRNA gene and 16S rRNA). Indications of surface water intrusion were identified in five wells, and these indications were found to be negatively correlated, overall, with bacterial alpha diversity (based on amplicon sequencing of the 16S rRNA gene). High levels of turbidity, heterotrophs, and iron compromised water quality in two wells, with values up to 2.98 nephelometric turbidity units (NTU), 16,000 CFU/ml, and 2,300 μg/liter, respectively. Coliform bacteria and general fecal indicator Bacteroidales bacteria (GenBac3) were detected in 14 and 10 wells, respectively (albeit mostly at low levels), and correlations were identified between microbial, physicochemical, and environmental parameters, which may indicate impacts from nearby land use (e.g., agriculture, surface water, road salt used for deicing). Our results show that although water quality was generally adequate in most of the studied wells, the continued safe use of these wells should not be taken for granted.

IMPORTANCE Standard physicochemical water quality analyses and microbial indicator analyses leave much of the (largely uncultured) complexity of groundwater microbial communities unexplored. This study combined these standard methods with additional analyses of stable water isotopes, bacterial community data, and environmental data about the surrounding areas to investigate the associations between physicochemical and microbial properties of 28 shallow groundwater wells in Finland. We detected impaired groundwater quality in some wells, identified potential land use impacts, and revealed indications of surface water intrusion which were negatively correlated with bacterial alpha diversity. The potential influence of surface water intrusion on groundwater wells and their bacterial communities is of particular interest and warrants further investigation because surface water intrusion has previously been linked to groundwater contamination, which is the primary cause of waterborne outbreaks in the Nordic region and one of the major causes in the United States and Canada.

Identifying challenges in drinking water supplies: assessment of boil water advisories in Norway (2008-2019)

The issuing of boil water advisories (BWAs) is a widely used response to microbiological contamination events in drinking water supply systems, and may therefore serve as an indicator for the access to safe drinking water. To supplement data source on the overall status of water supply systems (WSSs) in Norway, we analysed public media reports published in Norway to assess trends, causes, geographical and seasonal distribution of BWAs issued during the period 2008-2019. We identified 1,108 BWA events increasingly reported over the study period but characterised by a decreasing trend in time with respect to duration. The two main frequent causes for BWA were detection of faecal indicator bacteria (42.6%) and risk of contaminants intrusion in the distribution system (21%). We observed higher reporting rates in summer and autumn compared with winter, and higher reporting rates in Northern and Eastern Norwegian regions compared with the Central region. The results of this study could serve as supplementary information to better understand the overall status among WSSs in Norway, particularly in case of recurrent BWA's events, as well as suggest the relevance of BWAs' monitoring in identifying risk factors and planning targeted interventions.

Large waterborne Campylobacter outbreak: use of multiple approaches to investigate contamination of the drinking water supply system, Norway, June 2019

On 6 June 2019, the Norwegian Institute of Public Health was notified of more than 50 cases of gastroenteritis in Askøy. A reservoir in a water supply system was suspected as the source of the outbreak because of the acute onset and geographical distribution of cases. We investigated the outbreak to confirm the source, extent of the outbreak and effect of control measures. A case was defined as a person in a household served by Water Supply System A (WSS-A) who had gastroenteritis for more than 24 h between 1 and 19 June 2019. We conducted pilot interviews, a telephone survey and an SMS-based cohort study of residents served by WSS-A. System information of WSS-A was collected. Whole genome sequencing on human and environmental isolates was performed. Among 6,108 individuals, 1,573 fulfilled the case definition. Residents served by the reservoir had a 4.6× higher risk of illness than others. Campylobacter jejuni isolated from cases (n = 24) and water samples (n = 4) had identical core genome MLST profiles. Contamination through cracks in the reservoir most probably occurred during heavy rainfall. Water supply systems are susceptible to contamination, particularly to certain weather conditions. This highlights the importance of water safety planning and risk-based surveillance to mitigate risks.

Impact of average temperature, energy demand, sectoral value added, and population growth on water resource quality and mortality rate: it is time to stop waiting around

It is an overwhelming concern that increases in global average temperature lead to serious consequences on the natural environment in the form of deteriorating water resource quality and damaging healthcare sustainability agenda. The sustainable innovation forum (COP21) shows a high concern on climate changes and suggested to reduce global average temperature less than 2 °C. The study brings an idea from the stated theme and analyzed the relationship between climate change and water resource quality in order to redesign economic and environmental policies to improve water quality and healthcare sustainability in the context of Pakistan. The country has serious issues regarding the provision of safe drinking water, improved water resource quality, and healthcare sustainability, which can be achieved by sustainable policies to handle the extreme temperature in Pakistan. The study employed simultaneous generalized method of moments (GMM) technique in order to estimate parameters of the study during the period of 1980-2016. The results show that energy demand and industry value added substantially decrease water resource quality (WRQ), while agriculture value added and per capita income significantly increase WRQ in a country. The other regression apparatus, where health expenditures serve as the response variable, shows that average temperature, industry value added, population growth, and foreign direct investment (FDI) inflows significantly increase healthcare expenditures while WRQ has a negative impact on healthcare expenditures in a country. The final regression model shows that average temperature and per capita income decrease, while WRQ and industrial value added increase mortality rate in a country. The overall results confirm that WRQ affected by climate change, energy demand, and population growth that need sustainable water resource policies in order to achieve long-term sustained growth. The climate actions required more policy instruments to combat environmental challenges that should support healthcare sustainability agenda across the globe.

The establishment and first experiences of a crisis advisory service for water supplies in Norway

Water supply systems, in particular small-scale water supply systems, are vulnerable to adverse events that may jeopardise safe drinking water. The consequences of contamination events or the failure of daily operations may be severe, affecting many people. In Norway, a 24-hour crisis advisory service was established in 2017 to provide advice on national water supplies. Competent and expert advisors from water suppliers throughout the country assist other water suppliers and individuals who may be in need of advice during an adverse event. This paper describes the establishment of this service and experiences from the first three years of its operation. Since the launch of the service, water suppliers across Norway have consulted it approximately one to two times a month for advice, in particular about contamination events and near misses. The outcomes have helped to improve guidance on water hygiene issues at the national level.

Implementation of quantitative microbial risk assessment (QMRA) for public drinking water supplies: Systematic review

In the more than 15 years since its introduction, quantitative microbial risk assessment (QMRA) has become a widely used technique for assessing population health risk posed by waterborne pathogens. However, the variation in approaches taken for QMRA in relation to drinking water supply is not well understood. This systematic review identifies, categorises, and critically synthesises peer-reviewed and academic case studies of QMRA implementation for existing distributed public drinking water supplies. Thirty-nine English-language, peer-reviewed and academic studies published from 2003 to 2019 were identified. Key findings were synthesised in narrative form. The overall designs of the included studies varied widely, as did the assumptions used in risk calculation, especially in relation to pathogen dose. There was also substantial variation in the degree to which the use of location-specific data weighed with the use of assumptions when performing risk calculation. In general, the included studies' complexity did not appear to be associated with greater result certainty. Factors relating to pathogen dose were commonly influential on risk estimates whereas dose-response parameters tended to be of low relative influence. In two of the included studies, use of the 'susceptible fraction' factor was inconsistent with recognised guidance and potentially led to the underestimation of risk. While approaches and assumptions used in QMRA need not be standardised, improvement in the reporting of QMRA results and uncertainties would be beneficial. It is recommended that future authors consider the water supply QMRA reporting checklist developed for the current review. Consideration of the broad types of uncertainty relevant to QMRA is also recommended. Policy-makers should consider emergent discussion on acute microbial health-based targets when setting normative guidelines. The continued representation of QMRA case studies within peer-reviewed and academic literature would also enhance future implementation. Further research is needed on the optimisation of QMRA resourcing given the application context.

Exploring Well Water Testing Behaviour Through the Health Belief Model

Health problems can arise from consuming contaminated well water. Well water testing can help prevent negative health outcomes associated with consuming contaminated water. The aim of this study was to understand the factors influencing well owner decisions to conduct water testing through the theoretical lens of the Health Belief Model. We conducted semi-structured interviews with 20 well owners and used framework analysis to sort and analyse the data. The results demonstrated that well owners' perceived susceptibility to well water contamination was low, while the perceived severity of contamination, benefits of testing, and self-efficacy towards testing were high. Cues to action to promote testing focused on increasing well owner education and awareness through well stewardship programmes and reminders to test. Participants faced some barriers to water testing. Increasing education and awareness about well water contamination and water testing, while reducing logistical barriers to testing, may improve compliance with water testing.

Qualitative and quantitative use of micropollutants as source and process indicators. A review

Nowadays, micropollutants such as pharmaceuticals, pesticides and personal care products can be found ubiquitously in the anthropogenically influenced water cycle. As micropollutants have virtually no natural background concentrations they are significantly more sensitive in detecting processes and flow paths than classic inorganic tracers and indicators and at the same time they are often highly source specific. Therefore, using micropollutants as environmental indicators for anthropogenic activities is a common and frequently applied method today. As they interact in many ways with environmental matrices they can be used for source apportionment as well as to estimate flow paths and residence times in waterbodies. This review gives a systematic overview over the large variety of micropollutants used as indicators in the aquatic environment over the last decades together with the prerequisites on their use. Their application is subdivided into their qualitative (compound presence or absence) and quantitative (volume flows) use and shows the numerous possibilities from gaining basic information on the water regime up to advanced applications such as wastewater-based epidemiology.

Water safety plans and risk assessment: A novel procedure applied to treated water turbidity and gastrointestinal diseases

Water Safety Plans (WSPs), as recommended by the World Health Organization (WHO), can help drinking water suppliers to identify potential hazards related to drinking water and enable improvements in public health outcomes. In this study we propose a procedure to evaluate the health risk related to turbidity in finished water by determining the cases of drinking water-related gastrointestinal diseases. The results of several epidemiological studies and three-year time series turbidity data, coming from three different drinking water treatment plants (WTPs) located in Tuscany (Italy), have been used to determine the relationship between drinking water turbidity and gastroenteritis incidence and to assess the health risk attributable to the turbidity of tap water. The turbidity variation occurring in the treated water during the monitored period showed an incremental risk compared to the baseline value from 9% to 27% in the three WTPs. Risk reduction due to each treatment step was also evaluated and it was found that a complete treatment train (clari-flocculation, sand filtration, activated carbon filtration and multi-step disinfection) reduces risk by over 600 times. Our approach is a useful tool for water suppliers to quantify health risks by considering time series data on turbidity at WTPs and to make decisions regarding risk management measures.

Quantitative microbial risk assessment and its applications in small water systems: A review

Quantitative microbial risk assessment (QMRA) has been mainstreamed in many large municipal water systems as part of a paradigm shift in the drinking water industry towards water safety planning and risk-based system assessment. Small water systems (SWSs) are generally more vulnerable to typical water system hazards, and consequently have a higher risk of waterborne disease outbreak. In this paper, a review of experiences in implementing QMRA in SWSs helps elaborate the sources of risks and highlights some of the challenges facing SWSs in developed countries. A critical review of the important elements for practical implementation of QMRA was conducted. The investigation focuses on aspects related to challenges in identifying relevant hazards to SWSs to create failure scenarios, acquiring monitoring data for pathogens' concentrations in source water, estimating treatment efficiencies of typical small system technologies, and access to software tools to support successful implementation. The review helped outline ways through which SWSs can overcome the identified challenges in implementing QMRA. An adjusted framework for implementing QMRA for small water systems was formulated and discussed.

Detection of viable Escherichia coli in environmental water using combined propidium monoazide staining and quantitative PCR

The objectives of this study were to specifically detect viable Escherichia coli in environmental waters by targeting the ycjM gene in a propidium monoazide (PMA)-qPCR assay. PMA is a viability dye that can inhibit the amplification of DNA from dead cells, thus allowing for the detection and quantification of only viable cells. The ycjM primers were used to target E. coli that directly originated from the feces of warm blooded animals, and avoid false positive detection caused by "naturalized" E. coli that can exist in the environment. In this study, tap water and environmental waters were inoculated with E. coli isolated from animal feces. Following cell collection, samples were treated with PMA, followed by DNA isolation and qPCR detection. For pure cultures, 5 μM PMA with a 10-min light exposure was efficient at inhibiting the amplification of DNA from 10⁵ CFU/mL dead E. coli cells, with a detection limit of 10² CFU/100 mL viable cells. For tap and environmental waters collected in the winter, a 10 μM PMA was required and as low as 10³ CFU/100 mL viable cells could be detected in the presence of 10⁵ CFU/100 mL dead cells. For water samples collected during the summer, 10² CFU/10 mL viable cells could be detected in the presence of 10⁴ CFU/10 mL dead cells, after a 20 μM PMA treatment. No significant differences were found among the PMA-qPCR assay and two other standard culture-based methods for detection of viable E. coli in environmental water. In conclusion, with proper pretreatment of environmental water samples, this PMA-qPCR assay that targets the ycjM gene could quantify viable E. coli cells that directly come from the feces of warm-blooded animals, and therefore effectively and accurately indicate the quality of environmental water.

Time series study of weather, water quality, and acute gastroenteritis at Water Safety Plan implementation sites in France and Spain

Water Safety Plans (WSPs), recommended by the World Health Organization since 2004, can help drinking water suppliers to proactively identify potential risks and implement preventive barriers that improve safety. Few studies have investigated long-term impacts of WSPs, such as changes in drinking water quality or public health; however, some evidence from high-income countries associates WSP implementation with a reduction in diarrheal disease. To validate the previously observed linkages between WSPs and health outcomes, this time series study examined site-specific relationships between water-related exposures and acute gastroenteritis rates at three locations in France and Spain, including the role of WSP status. Relationships between control or exposure variables and health outcomes were tested using Poisson regression within generalized additive models. Controls included suspected temporal trends in disease reporting. Exposures included temperature, precipitation, raw water quality, and finished water quality (e.g., turbidity, free chlorine). In France, daily acute gastroenteritis cases were tracked using prescription reimbursements; Spanish data aggregated monthly acute gastroenteritis hospital visits. The models identified several significant relationships between indicators of exposure and acute gastroenteritis. Lag times of 6-9 days (including transit time) were most relevant for hydrological indicators (related to precipitation, runoff, and flow) at the two French sites, indicative of viral pathogens. Flush events (defined as surface runoff after a two-week antecedent dry period) linked to nonpoint source pollution were associated with a 10% increase in acute gastroenteritis rates at one location supplied by surface water. Acute gastroenteritis rates were positively associated with elevated turbidity average or maximum values in finished water at locations supplied by both surface and groundwater, by about 4% per 1-NTU increase in the two-week moving average of daily maxima or about 10% per 0.1 NTU increase in the prior month's average value. In some cases, risk appeared to be mitigated by WSP-related treatment interventions. Our results suggest drinking water exposure is associated with some potentially preventable gastrointestinal illness risk in high-income regions.

Do contamination of and exposure to chicken meat and water drive the temporal dynamics of Campylobacter cases?

Campylobacteriosis, the most frequent bacterial enteric disease, shows a clear yet unexplained seasonality. The study purpose was to explore the influence of seasonal fluctuation in the contamination of and in the behaviour exposures to two important sources of Campylobacter on the seasonality of campylobacteriosis. Time series analyses were applied to data collected through an integrated surveillance system in Canada in 2005-2010. Data included sporadic, domestically-acquired cases of Campylobacter jejuni infection, contamination of retail chicken meat and of surface water by C. jejuni, and exposure to each source through barbequing and swimming in natural waters. Seasonal patterns were evident for all variables with a peak in summer for human cases and for both exposures, in fall for chicken meat contamination, and in late fall for water contamination. Time series analyses showed that the observed campylobacteriosis summer peak could only be significantly linked to behaviour exposures rather than sources contamination (swimming rather than water contamination and barbequing rather than chicken meat contamination). The results indicate that the observed summer increase in human cases may be more the result of amplification through more frequent risky exposures rather than the result of an increase of the Campylobacter source contamination.

Laboratory-Scale Simulation and Real-Time Tracking of a Microbial Contamination Event and Subsequent Shock-Chlorination in Drinking Water

Rapid contamination of drinking water in distribution and storage systems can occur due to pressure drop, backflow, cross-connections, accidents, and bio-terrorism. Small volumes of a concentrated contaminant (e.g., wastewater) can contaminate large volumes of water in a very short time with potentially severe negative health impacts. The technical limitations of conventional, cultivation-based microbial detection methods neither allow for timely detection of such contaminations, nor for the real-time monitoring of subsequent emergency remediation measures (e.g., shock-chlorination). Here we applied a newly developed continuous, ultra high-frequency flow cytometry approach to track a rapid pollution event and subsequent disinfection of drinking water in an 80-min laboratory scale simulation. We quantified total (TCC) and intact (ICC) cell concentrations as well as flow cytometric fingerprints in parallel in real-time with two different staining methods. The ingress of wastewater was detectable almost immediately (i.e., after 0.6% volume change), significantly changing TCC, ICC, and the flow cytometric fingerprint. Shock chlorination was rapid and detected in real time, causing membrane damage in the vast majority of bacteria (i.e., drop of ICC from more than 380 cells μl^-1 to less than 30 cells μl^-1 within 4 min). Both of these effects as well as the final wash-in of fresh tap water followed calculated predictions well. Detailed and highly quantitative tracking of microbial dynamics at very short time scales and for different characteristics (e.g., concentration, membrane integrity) is feasible. This opens up multiple possibilities for targeted investigation of a myriad of bacterial short-term dynamics (e.g., disinfection, growth, detachment, operational changes) both in laboratory-scale research and full-scale system investigations in practice.

Application of landscape epidemiology to assess potential public health risk due to poor sanitation

Clear identification of areas vulnerable to waterborne diseases is essential for protecting community health. This is particularly important in developing countries where unsafe disposal of domestic wastewater and limited potable water supply pose potential public health risks. However, data paucity can be a compounding issue. Under these circumstances, landscape epidemiology can be applied as a resource efficient approach for mapping potential disease risk areas associated with poor sanitation. However, in order to realise the full potential offered by this approach, an in-depth understanding of the impact of different classes of an explanatory variable on a target disease and the validity of hotspot analysis using limited datasets is needed. Accordingly, this research study focused on typhoid and diarrhoea incidence with respect to different classes of elevation, flood inundation, land use, soil permeability, population density and rainfall as explanatory variables. An integrated methodology consisting of hot spot analysis and Poisson regression was employed to map potential disease risk areas. The study findings confirmed the significant differences in the influence exerted by the various classes of an explanatory variable in relation to a target disease. The results also confirmed the feasibility of the hotspot analysis for identifying areas vulnerable to the target diseases using a limited dataset. The study outcomes are expected to contribute to creating an in-depth understanding of the relationship between disease prevalence and associated landscape factors for the delineation of disease risk zones in the context of data paucity.

Assessment of chlorine tolerance profile of Citrobacter species recovered from wastewater treatment plants in Eastern Cape, South Africa

This present study assessed the chlorine tolerance of some Citrobacter species recovered from secondary effluents from the clarifiers of two wastewater treatment plants in the Eastern Cape, South Africa. The bacterial survival, chlorine lethal dose and inactivation kinetics at lethal doses were examined. Inactivation of the test bacteria (n = 20) at the recommended dose of 0.5 mg/l for 30 min exposure showed a progressive reduction in bacterial population from 4 to 5 log reduction and residuals ranged between 0.12 and 0.46 mg/l. The bactericidal activity of chlorine increased at higher dosages with a substantial reduction in viability of the bacteria and complete inactivation of the bacterial population at a lethal dose of 0.75 and 1.0 mg/l in 30 min. For the inactivation kinetics, bactericidal activity of chlorine increased with time showing a 3.67-5.4 log reduction in 10 min, 4.0-5.6 log reduction in 20 min and above 6.3 log reductions to complete sterilization of bacterial population over 30 min for all the entire test Citrobacter isolates used in this study. Furthermore, there was a strong correlation (R ² > 0.84) between bacteria inactivation and increase in contact time. This study appears to have provided support for laboratory evidence of bacterial tolerance to chlorine disinfection at current recommended dose (0.5 mg/l for 30 min), and chlorine concentration between 0.75 and 1.0 mg/l was found to have a better disinfecting capacity to check tolerance of Citrobacter species.

Safe drinking water and waterborne outbreaks

The present work compiles a review on drinking waterborne outbreaks, with the perspective of production and distribution of microbiologically safe water, during 2000-2014. The outbreaks are categorised in raw water contamination, treatment deficiencies and distribution network failure. The main causes for contamination were: for groundwater, intrusion of animal faeces or wastewater due to heavy rain; in surface water, discharge of wastewater into the water source and increased turbidity and colour; at treatment plants, malfunctioning of the disinfection equipment; and for distribution systems, cross-connections, pipe breaks and wastewater intrusion into the network. Pathogens causing the largest number of affected consumers were Cryptosporidium, norovirus, Giardia, Campylobacter, and rotavirus. The largest number of different pathogens was found for the treatment works and the distribution network. The largest number of affected consumers with gastrointestinal illness was for contamination events from a surface water source, while the largest number of individual events occurred for the distribution network.

Microbial health-based targets for drinking water: current state and Australian case study

Through the avoidance of a substantial health burden globally, access to safe drinking water is an important foundation of public health1. An emerging development in this regard is the use of public health metrics, such as disability-adjusted life years, to inform water safety planning2. This paper examines the hypothesis that confidence in the protection of public health, on the part of water suppliers, health regulators, and ultimately consumers is strengthened through the implementation of a health outcome target for the microbial safety of drinking water. A case study demonstrating the implementation of the target is presented.

Fecal Bacteria, Bacteriophage, and Nutrient Reductions in a Full-Scale Denitrifying Woodchip Bioreactor

Denitrifying bioreactors using woodchips or other slow-release carbon sources can be an effective method for removing nitrate (NO) from wastewater and tile drainage. However, the ability of these systems to remove fecal microbes from wastewater has been largely uninvestigated. In this study, reductions in fecal indicator bacteria () and viruses (F-specific RNA bacteriophage [FRNA phage]) were analyzed by monthly sampling along a longitudinal transect within a full-scale denitrifying woodchip bioreactor receiving secondary-treated septic tank effluent. Nitrogen, phosphorus, 5-d carbonaceous biochemical oxygen demand (CBOD), and total suspended solids (TSS) reduction were also assessed. The bioreactor demonstrated consistent and substantial reduction of (2.9 log reduction) and FRNA phage (3.9 log reduction) despite receiving highly fluctuating inflow concentrations [up to 3.5 × 10 MPN (100 mL) and 1.1 × 10 plaque-forming units (100 mL) , respectively]. Most of the removal of fecal microbial contaminants occurred within the first meter of the system (1.4 log reduction for ; 1.8 log reduction for FRNA phage). The system was also efficient at removing NO (>99.9% reduction) and TSS (89% reduction). There was no evidence of consistent removal of ammonium, organic nitrogen, or phosphorus. Leaching of CBOD occurred during initial operation but decreased and stabilized at lower values (14 g O m) after 9 mo. We present strong evidence for reliable microbial contaminant removal in denitrifying bioreactors, demonstrating their broader versatility for wastewater treatment. Research on the removal mechanisms of microbial contaminants in these systems, together with the assessment of longevity of removal, is warranted.

Ultrafiltration and Microarray for Detection of Microbial Source Tracking Marker and Pathogen Genes in Riverine and Marine Systems

Pathogen identification and microbial source tracking (MST) to identify sources of fecal pollution improve evaluation of water quality. They contribute to improved assessment of human health risks and remediation of pollution sources. An MST microarray was used to simultaneously detect genes for multiple pathogens and indicators of fecal pollution in freshwater, marine water, sewage-contaminated freshwater and marine water, and treated wastewater. Dead-end ultrafiltration (DEUF) was used to concentrate organisms from water samples, yielding a recovery efficiency of >95% for Escherichia coli and human polyomavirus. Whole-genome amplification (WGA) increased gene copies from ultrafiltered samples and increased the sensitivity of the microarray. Viruses (adenovirus, bocavirus, hepatitis A virus, and human polyomaviruses) were detected in sewage-contaminated samples. Pathogens such as Legionella pneumophila, Shigella flexneri, and Campylobacter fetus were detected along with genes conferring resistance to aminoglycosides, beta-lactams, and tetracycline. Nonmetric dimensional analysis of MST marker genes grouped sewage-spiked freshwater and marine samples with sewage and apart from other fecal sources. The sensitivity (percent true positives) of the microarray probes for gene targets anticipated in sewage was 51 to 57% and was lower than the specificity (percent true negatives; 79 to 81%). A linear relationship between gene copies determined by quantitative PCR and microarray fluorescence was found, indicating the semiquantitative nature of the MST microarray. These results indicate that ultrafiltration coupled with WGA provides sufficient nucleic acids for detection of viruses, bacteria, protozoa, and antibiotic resistance genes by the microarray in applications ranging from beach monitoring to risk assessment.

Integrated frameworks for assessing and managing health risks in the context of managed aquifer recharge with river water

Integrated assessment and management of water resources for the supply of potable water is increasingly important in light of projected water scarcity in many parts of the world. This article develops frameworks for regional-level waterborne human health risk assessment of chemical and microbiological contamination to aid water management, incorporating economic aspects of health risks. Managed aquifer recharge with surface water from a river in Southern Finland is used as an illustrative case. With a starting point in watershed governance, stakeholder concerns, and value-at-risk concepts, we merge common methods for integrative health risk analysis of contaminants to describe risks and impacts dynamically and broadly. This involves structuring analyses along the risk chain: sources-releases-environmental transport and fate-exposures-health effects-socio-economic impacts-management responses. Risks attributed to contaminants are embedded in other risks, such as contaminants from other sources, and related to benefits from improved water quality. A set of models along this risk chain in the case is presented. Fundamental issues in the assessment are identified, including 1) framing of risks, scenarios, and choices; 2) interaction of models and empirical information; 3) time dimension; 4) distributions of risks and benefits; and 5) uncertainties about risks and controls. We find that all these combine objective and subjective aspects, and involve value judgments and policy choices. We conclude with proposals for overcoming conceptual and functional divides and lock-ins to improve modeling, assessment, and management of complex water supply schemes, especially by reflective solution-oriented interdisciplinary and multi-actor deliberation.

Extreme weather events: Should drinking water quality management systems adapt to changing risk profiles?

Among the most widely predicted and accepted consequences of global climate change are increases in both the frequency and severity of a variety of extreme weather events. Such weather events include heavy rainfall and floods, cyclones, droughts, heatwaves, extreme cold, and wildfires, each of which can potentially impact drinking water quality by affecting water catchments, storage reservoirs, the performance of water treatment processes or the integrity of distribution systems. Drinking water guidelines, such as the Australian Drinking Water Guidelines and the World Health Organization Guidelines for Drinking-water Quality, provide guidance for the safe management of drinking water. These documents present principles and strategies for managing risks that may be posed to drinking water quality. While these principles and strategies are applicable to all types of water quality risks, very little specific attention has been paid to the management of extreme weather events. We present a review of recent literature on water quality impacts of extreme weather events and consider practical opportunities for improved guidance for water managers. We conclude that there is a case for an enhanced focus on the management of water quality impacts from extreme weather events in future revisions of water quality guidance documents.

Cattle-derived microbial input to source water catchments: An experimental assessment of stream crossing modification

The provision of safe drinking water is a global issue, and animal production is recognized as a significant potential origin of human infectious pathogenic microorganisms within source water catchments. On-farm management can be used to mitigate livestock-derived microbial pollution in source water catchments to reduce the risk of contamination to potable water supplies. We applied a modified Before-After Control Impact (BACI) design to test if restricting the access of livestock to direct contact with streams prevented longitudinal increases in the concentrations of faecal indicator bacteria and suspended solids. Significant longitudinal increases in pollutant concentrations were detected between upstream and downstream reaches of the control crossing, whereas such increases were not detected at the treatment crossing. Therefore, while the crossing upgrade was effective in preventing cattle-derived point source pollution by between 112 and 158%, diffuse source pollution to water supplies from livestock is not ameliorated by this intervention alone. Our findings indicate that stream crossings that prevent direct contact between livestock and waterways provide a simple method for reducing pollutant loads in source water catchments, which ultimately minimises the likelihood of pathogenic microorganisms passing through source water catchments and the drinking water supply system. The efficacy of the catchment as a primary barrier to pathogenic risks to drinking water supplies would be improved with the integration of management interventions that minimise direct contact between livestock and waterways, combined with the mitigation of diffuse sources of livestock-derived faecal matter from farmland runoff to the aquatic environment.

Water systems, sanitation, and public health risks in remote communities: Inuit resident perspectives from the Canadian Arctic

Safe drinking water and wastewater sanitation are universally recognized as critical components of public health. It is well documented that a lack of access to these basic services results in millions of preventable deaths each year among vulnerable populations. Water and wastewater technologies and management practices are frequently tailored to local environmental conditions. Also important, but often overlooked in water management planning, are the social, cultural and economic contexts in which services are provided. The purpose of this qualitative case study was to identify and understand residents' perceptions of the functionality of current water and wastewater sanitation systems in one vulnerable context, that of a remote Arctic Aboriginal community (Coral Harbour, Nunavut), and to identify potential future water related health risks. Semi-structured interviews were conducted with 28 Inuit residents and 9 key informants in 2011 and 2012. Findings indicate that the population's rapid transition from a semi-nomadic hunting and gathering lifestyle to permanent settlements with municipally provided utilities is influencing present-day water usage patterns, public health perceptions, and the level of priority decision-makers place on water and wastewater management issues. Simultaneously environmental, social and cultural conditions conducive to increased human exposure to waterborne health risks were also found to exist and may be increasing in the settlements. While water and wastewater system design decisions are often based on best practices proven suitable in similar environmental conditions, this study reinforces the argument for inclusion of social, cultural, and economic variables in such decisions, particularly in remote and economically challenged contexts in Canada or elsewhere around the world. The results also indicate that the addition of qualitative data about water and wastewater systems users' behaviours to technical knowledge of systems and operations can enhance the understanding of human-water interactions and be valuable in risk assessments and intervention development.

Acute gastrointestinal illness in two Inuit communities: burden of illness in Rigolet and Iqaluit, Canada

Food- and waterborne disease is thought to be high in some Canadian Indigenous communities; however, the burden of acute gastrointestinal illness (AGI) is not well understood due to limited availability and quality of surveillance data. This study estimated the burden of community-level self-reported AGI in the Inuit communities of Rigolet, Nunatsiavut, and Iqaluit, Nunavut, Canada. Cross-sectional retrospective surveys captured information on AGI and potential environmental risk factors. Multivariable logistic regression models identified potential AGI risk factors. The annual incidence of AGI ranged from 2·9-3·9 cases/person per year in Rigolet and Iqaluit. In Rigolet, increased spending on obtaining country foods, a homeless person in the house, not visiting a cabin recently, exposure to puppies, and alternative sources of drinking water were associated with increased odds of AGI. In Iqaluit, eating country fish often, exposure to cats, employment status of the person responsible for food preparation, not washing the countertop with soap after preparing meat, a homeless person in the house, and overcrowding were associated with increased odds of AGI. The results highlight the need for systematic data collection to better understand and support previously anecdotal indications of high AGI incidence, as well as insights into unique AGI environmental risk factors in Indigenous populations.

Drinking water quality and public health in Southwestern Saudi Arabia: The need for a national monitoring program

Aim of the Study:

The aim was to investigate the bacteriological quality of drinking water, and explore the factors involved in the knowledge of the public about the quality of drinking water in Najran region, Saudi Arabia.

Study Design:

A cross-sectional descriptive study.

Materials and Methods:

A total of 160 water samples were collected. Total coliforms, fecal coliform, and fecal streptococci were counted using Most Probable Number method. The bacterial genes lacZ and uidA specific to total coliforms and Escherichia coli, respectively, were detected using multiplex polymerase chain reaction. An interview was conducted with 1200 residents using a questionnaire.

Results:

Total coliforms were detected in 8 (20%) of 40 samples from wells, 13 (32.5%) of 40 samples from tankers, and 55 (68.8%) of 80 samples from roof tanks. Twenty (25%) and 8 (10%) samples from roof tanks were positive for E. coli and Streptococcus faecalis, respectively. Of the 1200 residents participating in the study, 10%, 45.5%, and 44.5% claimed that they depended on municipal water, bottled water, and well water, respectively. The majority (95.5%) reported the use of roof water tanks as a source of water supply in their homes. Most people (80%) believed that drinking water transmitted diseases. However, only 25% of them participated in educational programs on the effect of polluted water on health.

Conclusions:

Our results could help health authorities consider a proper regular monitoring program and a sustainable continuous assessment of the quality of well water. In addition, this study highlights the importance of the awareness and educational programs for residents on the effect of polluted water on public health.

Heterogeneity: a major factor influencing microbial exposure and risk assessment

Microbial risk assessment is dependent on several biological and environmental factors that affect both the exposure characteristics to the biological agents and the mechanisms of pathogenicity involved in the pathogen-host relationship. Many exposure assessment studies still focus on the location parameters of the probability distribution representing the concentration of the pathogens and/or toxin. However, the mean or median by themselves are insufficient to evaluate the adverse effects that are associated with a given level of exposure. Therefore, the effects on the risk of disease of a number of factors, including the shape parameters characterizing the distribution patterns of the pathogen in their environment, were investigated. The statistical models, which were developed to provide a better understanding of the factors influencing the risk, highlight the role of heterogeneity and its consequences on the commonly used risk assessment paradigm. Indeed, the heterogeneity characterizing the spatial and temporal distribution of the pathogen and/or the toxin contained in the water or food consumed is shown to be a major factor that may influence the magnitude of the risk dramatically. In general, the risk diminishes with higher levels of heterogeneity. This scheme is totally inverted in the presence of a threshold in the dose-response relationship, since heterogeneity will then have a tremendous impact, namely, by magnifying the risk when the mean concentration of pathogens is below the threshold. Moreover, the approach of this article may be useful for risk ranking analysis, regarding different exposure conditions, and may also lead to improved water and food quality guidelines.

Groundwater source contamination mechanisms: physicochemical profile clustering, risk factor analysis and multivariate modelling

An integrated domestic well sampling and "susceptibility assessment" programme was undertaken in the Republic of Ireland from April 2008 to November 2010. Overall, 211 domestic wells were sampled, assessed and collated with local climate data. Based upon groundwater physicochemical profile, three clusters have been identified and characterised by source type (borehole or hand-dug well) and local geological setting. Statistical analysis indicates that cluster membership is significantly associated with the prevalence of bacteria (p=0.001), with mean Escherichia coli presence within clusters ranging from 15.4% (Cluster-1) to 47.6% (Cluster-3). Bivariate risk factor analysis shows that on-site septic tank presence was the only risk factor significantly associated (p<0.05) with bacterial presence within all clusters. Point agriculture adjacency was significantly associated with both borehole-related clusters. Well design criteria were associated with hand-dug wells and boreholes in areas characterised by high permeability subsoils, while local geological setting was significant for hand-dug wells and boreholes in areas dominated by low/moderate permeability subsoils. Multivariate susceptibility models were developed for all clusters, with predictive accuracies of 84% (Cluster-1) to 91% (Cluster-2) achieved. Septic tank setback was a common variable within all multivariate models, while agricultural sources were also significant, albeit to a lesser degree. Furthermore, well liner clearance was a significant factor in all models, indicating that direct surface ingress is a significant well contamination mechanism. Identification and elucidation of cluster-specific contamination mechanisms may be used to develop improved overall risk management and wellhead protection strategies, while also informing future remediation and maintenance efforts.

Comprehensive analysis of prokaryotes in environmental water using DNA microarray analysis and whole genome amplification

The microflora in environmental water consists of a high density and diversity of bacterial species that form the foundation of the water ecosystem. Because the majority of these species cannot be cultured in vitro, a different approach is needed to identify prokaryotes in environmental water. A novel DNA microarray was developed as a simplified detection protocol. Multiple DNA probes were designed against each of the 97,927 sequences in the DNA Data Bank of Japan and mounted on a glass chip in duplicate. Evaluation of the microarray was performed using the DNA extracted from one liter of environmental water samples collected from seven sites in Japan. The extracted DNA was uniformly amplified using whole genome amplification (WGA), labeled with Cy3-conjugated 16S rRNA specific primers and hybridized to the microarray. The microarray successfully identified soil bacteria and environment-specific bacteria clusters. The DNA microarray described herein can be a useful tool in evaluating the diversity of prokaryotes and assessing environmental changes such as global warming.

Monitoring of adenovirus serotypes in environmental samples by combined PCR and melting point analyses

BACKGROUND

Human adenoviruses are promising candidates for addressing health risks associated with enteric viruses in environmental waters. Relatively harmless but common, these DNA viruses persist within the population and are generally considered extremely stable, remaining infectious in water for long periods of time. Group-specific or single species detection of human adenoviruses in environmental samples is usually based on polymerase chain reaction assays. Simultaneous identification of specific species or serotypes needs additional processing. Here we present a simple molecular approach for the monitoring of serotypic diversity in the human adenovirus populations in contaminated water sites.

METHODS

Diversity patterns of human adenoviruses in environmental samples, collected in an outdoor artificial stream and pond simulation system, were analyzed using a closed tube polymerase chain reaction method with subsequent melting point analysis.

RESULTS

Human adenovirus serotype 41 was the most prominent adenovirus serotype detected in environmental water samples, but melting point analyses indicated the presence of additional adenovirus serotypes.

CONCLUSIONS

Based on investigations with spiked and environmental samples, a combination of qPCR and melting point analysis was shown to identify adenovirus serotypes in sewage contaminated water.

Bacteriological and physicochemical studies on Tigris River near the water purification stations within Baghdad Province

We studied the physical, chemical, and microbiological factors that influence drinking water quality processed from River Tigris, and of the three main drinking water purification stations located at different parts of Tigris River, along with evaluation of drinking water of Al-Shula region in Baghdad city. Water samples were taken monthly from December 2009 to September 2010. Physical and chemical analyses of water included determination of temperature, pH, turbidity, electrical conductivity, total dissolved solids, salinity, dissolved oxygen, and biological oxygen demand. The results of water before and after purification indicated values within the international allowable levels. Microbial analyses included estimation of the number of total viable microbial counts, total coliform, total fecal E. coli and Pseudomonas aeruginosa, and other pathogenic bacteria that might be present in the water of the three stations and of the Tigris River, and also the tap water from Al-Shula houses. The results indicated that the types and proportions of various bacterial species isolated from different water sources were almost similar. This indicates inefficient purification procedures in all the stations studied, which exceeded the internationally allowable level of pathogens in potable water. Also, this explains the high incidence rate of children diarrheal reported in Al-Shula region.

Spatial and temporal drivers of zoonotic pathogen contamination of an agricultural watershed

In regions where animal agriculture is prominent, such as southern Alberta, higher rates of gastrointestinal illness have been reported when compared with nonagricultural regions. This difference in the rate of illness is thought to be a result of increased zoonotic pathogen exposure through environmental sources such as water. In this study, temporal and spatial factors associated with bacterial pathogen contamination of the Oldman River, which transverses this region, were analyzed using classification and regression tree analysis. Significantly higher levels of fecal indicators; more frequent isolations of Campylobacter spp., Escherichia coli O157:H7, and Salmonella enterica spp.; and higher rates of detection of pig-specific Bacteroides markers occurred at downstream sites than at upstream sites, suggesting additive stream inputs. Fecal indicator densities were also significantly higher when any one of these three bacterial pathogens was present and where there were higher total animal manure units; however, occasionally pathogens were present when fecal indicator levels were low or undetectable. Overall, Salmonella spp., Campylobacter spp., and E. coli O157:H7 presence was associated with season, animal manure units, and total rainfall on the day of sampling and 3 d in advance of sampling. Several of the environmental variables analyzed in this study appear to influence pathogen prevalence and therefore may be useful in predicting water quality and safety and in the improvement of watershed management practices in this and other agricultural regions.

Preparation of highly luminescent mannose-gold nanodots for detection and inhibition of growth of Escherichia coli

In this paper, we describe a novel, simple, and convenient method for preparing water-soluble biofunctional gold nanodots (Au NDs) for the sensitive and selective detection of Escherichia coli (E. coli) and the inhibition of its growth. We obtained luminescent mannose-capped Au NDs (Man-Au NDs) from as-prepared 2.9-nm Au nanoparticles (Au NPs) and 29,29'-dithio bis(3',6',9',12',15',18'-hexaoxa-nonacosyl α-D-mannopyranoside) (Man-RSSR-Man). To obtain improved quantum yield (>20%), luminescent Man-Au NDs (1.8 nm) were prepared from Au NPs (0.47 μM) and Man-RSSR-Man (2.5 mM) in the presence of sodium borohydride (NaBH(4); 1.0 mM). The highly luminescent properties of Man-Au NDs prepared by the NaBH(4)-assisted method were characterized by UV-vis absorption, photoluminescence, and X-ray photoelectron spectroscopies. The results supported the high-density coverage of the NDs surface by Man-RS ligands. Multivalent interactions between Man-Au NDs and FimH proteins located on the bacterial pili of E. coli resulted in the formation of aggregated cell clusters. After concentrating this agglutinative E. coli from a large-volume cell solution (5 mL), Man-Au NDs were displaced by mannose (100 mM) and stabilized by Man-RSSR-Man (5 mM). Monitoring the luminescence of Man-Au NDs allowed the detection of E. coli at levels as low as 150 CFU/mL. Man-Au NDs were also found to be efficient antibacterial agents, selectively inhibiting the growth of E. coli through Man-Au ND-induced agglutination. Our small-diameter Man-Au NDs, which provided an ultra high ligand density (local concentration) of mannose units for multivalent interactions with E. coli, have great potential for use as an antibacterial agent in other applications.

Microbial contamination of groundwater at small community water supplies in Finland

The raw water quality and associations between the factors considered as threats to water safety were studied in 20 groundwater supplies in central Finland in 2002-2004. Faecal contaminations indicated by the appearance of Escherichia coli or intestinal enterococci were present in five small community water supplies, all these managed by local water cooperatives. Elevated concentrations of nutrients in raw water were linked with the presence of faecal bacteria. The presence of on-site technical hazards to water safety, such as inadequate well construction and maintenance enabling surface water to enter into the well and the insufficient depth of protective soil layers above the groundwater table, showed the vulnerability of the quality of groundwater used for drinking purposes. To minimize the risk of waterborne illnesses, the vulnerable water supplies need to be identified and appropriate prevention measures such as disinfection should be applied.

Weather, water quality and infectious gastrointestinal illness in two Inuit communities in Nunatsiavut, Canada: potential implications for climate change

Climate change is expected to cause changes in precipitation quantity, intensity, frequency and duration, which will subsequently alter environmental conditions and might increase the risk of waterborne disease. The objective of this study was to describe the seasonality of and explore associations between weather, water quality and occurrence of infectious gastrointestinal illnesses (IGI) in two communities in Nunatsiavut, Canada. Weather data were obtained from meteorological stations in Nain (2005-2008) and Rigolet (2008). Free-chlorine residual levels in drinking water were extracted from municipal records (2005-2008). Raw surface water was tested weekly for total coliform and E. coli counts. Daily counts of IGI-related clinic visits were obtained from health clinic registries (2005-2008). Analysis of weather and health variables included seasonal-trend decomposition procedures based on Loess. Multivariable zero-inflated Poisson regression was used to examine potential associations between weather events (considering 0-4 week lag periods) and IGI-related clinic visits. In Nain, water volume input (rainfall + snowmelt) peaked in spring and summer and was positively associated with levels of raw water bacteriological variables. The number of IGI-related clinic visits peaked in the summer and fall months. Significant positive associations were observed between high levels of water volume input 2 and 4 weeks prior, and IGI-related clinic visits (P < 0.05). This study is the first to systematically gather, analyse and compare baseline data on weather, water quality and health in Nunatsiavut, and illustrates the need for high quality temporal baseline information to allow for detection of future impacts of climate change on regional Inuit human and environmental health.

Do free-living amoebae in treated drinking water systems present an emerging health risk?

There is an expanding body of evidence that free-living amoebae (FLA) increase both the numbers and virulence of water-based, human-pathogenic, amoeba-resisting microorganisms (ARM). Legionella spp., Mycobacterium spp., and other opportunistic human pathogens are known to be both ARM and also the etiologic agents of potentially fatal human lung infections. However, comparatively little is known about the FLA that may facilitate ARM growth in drinking water. This review examines the available literature on FLA in treated drinking water systems; in total 26 studies from 18 different countries. FLA were reported to breakthrough the water treatment barrier and enter distribution systems, in addition to the expected post-treatment system ingress. Once in the distribution system there is evidence of FLA colonization and regrowth especially in reservoirs and in-premise plumbing storage tanks. At the point of use the average FLA detection rate was 45% but highly variable (n = 16, σ = 31) due to both differences in both assay methods and the type of water systems examined. This review reveals that FLA are consistently detected in treated drinking water systems around the world and present a yet unquantified emerging health risk. However, more research is urgently required before accurate risks assessments can be undertaken to assess the impacts on human health, in households and institutions, due to exposure to FLA facilitated pathogenic ARM.

Molecular subtypes of Campylobacter spp., Salmonella enterica, and Escherichia coli O157:H7 isolated from faecal and surface water samples in the Oldman River watershed, Alberta, Canada

Campylobacter spp., Salmonella enterica, and Escherichia coli O157:H7 isolated from 898 faecal, 43 sewage, and 342 surface water samples from the Oldman River were characterized using bacterial subtyping methods in order to investigate potential sources of contamination of the watershed. Among these pathogens, Campylobacter spp. were the most frequently isolated from faecal, sewage, and surface water samples (266/895, 11/43, and 91/342, respectively), followed by Salmonella (67/898, 8/43, and 29/342, respectively), and E. coli O157:H7 (16/898, 2/43, and 8/342, respectively). Salmonella Rubislaw was the most common serovar isolated from water. This serovar was also isolated from two wild bird species. Most other serovars isolated from water were either not isolated from animals or were isolated from multiple species. E. coli O157:H7 was predominantly isolated from cattle. The most common phage-types of this pathogen from cattle were also the most common among water isolates, and there were exact pulsed field gel electrophoresis and comparative genomic fingerprint matches between cattle, sewage, and water isolates. Campylobacters were commonly isolated from surface waters and faeces from most animal species. Restriction fragment length polymorphism of the Campylobacter flaA gene identified several location and host species-specific (cattle, goose, pig) fingerprints. Molecular subtyping of these bacterial pathogens shows considerable promise as a tool for determining the sources of faecal pollution of water.

Nanogold-based sensing of environmental toxins: excitement and challenges

There have been tremendous advances in the past ten years on the development of various nanomaterials-based sensors for detection of environmental toxins. Nanogold is of special interest because of its unique shape- and size-dependent optical properties, hyper-quenching ability, super surface-enhanced Raman and dynamic light scattering, and surface-modifiability by small organic molecules and biomolecules. These unique optical properties of nanogold have been explored for ultra-sensitive detection, while its surface-modifiability has been explored for selectivity. In general, the nanogold-based sensors are highly selective and sensitive along with simple sample preparation and sensor design. In this review article, we intend to capture some of the recent advances in nanogold-based sensor development and mechanistic studies, especially for bacteria, heavy metals, and nitroaromatic compounds. Undoubtedly, these developments will generate a lot of excitement for environmental scientists and toxicologists as well as the general public.

An extensive gastroenteritis outbreak after drinking-water contamination by sewage effluent, Finland

An inappropriate cross-connection between sewage- and drinking-water pipelines contaminated tap water in a Finnish town, resulting in an extensive waterborne gastroenteritis outbreak in this developed country. According to a database and a line-list, altogether 1222 subjects sought medical care as a result of this exposure. Seven pathogens were found in patient samples of those who sought treatment. To establish the true disease burden from this exposure, we undertook a population-based questionnaire investigation with a control population, infrequently used to study waterborne outbreaks. The study covered three areas, contaminated and uncontaminated parts of the town and a control town. An estimated 8453 residents fell ill during the outbreak, the excess number of illnesses being 6501. Attack rates were 53% [95% confidence interval (CI) 49.5-56.4] in the contaminated area, 15.6% (95% CI 13.1-18.5) in the uncontaminated area and 6.5% (95% CI 4.8-8.8) in the control population. Using a control population allowed us to differentiate baseline morbidity from the observed morbidity caused by the water contamination, thus enabling a more accurate estimate of the disease burden of this outbreak.

Removal of sediment and bacteria from water using green chemistry

Although nearly all newly derived water purification methods have improved the water quality in developing countries, few have been accepted and maintained for long-term use. Field studies indicate that the most beneficial methods use indigenous resources, as they are both accessible and accepted by communities they help. In an effort to implement a material that will meet community needs, two fractions of mucilage gum were extracted from the Opuntia ficus-indica cactus and tested as flocculation agents against sediment and bacterial contamination. As diatomic ions are known to affect both mucilage and promote cell aggregation, CaCl(2) was studied in conjunction and compared with mucilage as a bacteria removal method. To evaluate performance, ion-rich waters that mimic natural water bodies were prepared. Column tests containing suspensions of the sediment kaolin exhibited particle flocculation and settling rates up to 13.2 cm/min with mucilage versus control settling rates of 0.5 cm/min. Bacillus cereus tests displayed flocculation and improved settling times with mucilage concentrations lower than 5 ppm and removal rates between 97 and 98% were observed for high bacteria concentration tests (>10(8) cells/ml). This natural material not only displays water purification abilities, but it is also affordable, renewable and readily available.