Estimating the burden of acute gastrointestinal illness due to Giardia, Cryptosporidium, Campylobacter, E. coli O157 and norovirus associated with private wells and small water systems in Canada

The estimated burden of endemic acute gastrointestinal illness (AGI) annually in Canada is 20·5 million cases. Approximately 4 million of these cases are domestically acquired and foodborne, yet the proportion of waterborne cases is unknown. A number of randomized controlled trials have been completed to estimate the influence of tap water from municipal drinking water plants on the burden of AGI. In Canada, 83% of the population (28 521 761 people) consumes tap water from municipal drinking water plants serving >1000 people. The drinking water-related AGI burden associated with the consumption of water from these systems in Canada is unknown. The objective of this research was to estimate the number of AGI cases attributable to consumption of drinking water from large municipal water supplies in Canada, using data from four household drinking water intervention trials. Canadian municipal water treatment systems were ranked into four categories based on source water type and quality, population size served, and treatment capability and barriers. The water treatment plants studied in the four household drinking water intervention trials were also ranked according to the aforementioned criteria, and the Canadian treatment plants were then scored against these criteria to develop four AGI risk groups. The proportion of illnesses attributed to distribution system events vs. source water quality/treatment failures was also estimated, to inform the focus of future intervention efforts. It is estimated that 334 966 cases (90% probability interval 183 006-501 026) of AGI per year are associated with the consumption of tap water from municipal systems that serve >1000 people in Canada. This study provides a framework for estimating the burden of waterborne illness at a national level and identifying existing knowledge gaps for future research and surveillance efforts, in Canada and abroad.

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.

To determine the burden and distribution of acute gastrointestinal illness (AGI) in the population, a cross-sectional, monthly face-to-face survey of 10 959 residents was conducted in Jiangsu province between July 2010 and June 2011. The adjusted monthly prevalence was 4.7% with 0.63 AGI episodes/person per year. The prevalence was the highest in children aged <5 years and lowest in persons aged ≥ 65 years. A bimodal seasonal distribution was observed with peaks in summer and winter. Regional difference of AGI prevalence was substantial [lowest 0.5% in Taicang, highest 15.1% in Xinqu (Wuxi prefecture)]. Healthcare was sought by 38.4% of the ill respondents. The use of antibiotics was reported by 65·2% of the ill respondents and 38.9% took antidiarrhoeals. In the multivariable model, gender, education, season, sentinel site and travel were significant risk factors of being a case of AGI. These results highlight the substantial burden of AGI and the risk factors associated with AGI in Jiangsu province, China.

BACKGROUND AND AIM: Louisiana faces risks of an oncoming water crisis that will be intensified by both man-made and natural threats. Climate models predict an increase in the frequency and magnitude of storms, precipitation, and flooding in Louisiana in the upcoming decades; while gaps in regulatory oversight and enforcement, weaknesses public health recommendations, and corrosion of drinking water infrastructure threatens delivery of clean water to vulnerable communities. METHODS: Results are presented from several independent investigations of private well or small community water systems throughout Louisiana. RESULTS:Several cases of private, small or rural water systems were uncovered which pose public health threats, despite the fact that they have historically complied with regulatory requirements, or conformed to public health recommendations for water system maintenance. In New Orleans, while water lead levels met regulatory requirements, prevailing recommendations for reducing exposures through flushing and partial line replacements were not only inconsistently effective, but could also inadvertently increase exposures. In Louisiana, an estimated 400 water systems have excess iron, a largely unregulated nutrient; but monitoring of two compliant systems with high iron revealed conditions which can impact public health, including mobilization of trace inorganics like lead, depletion of free chlorine residual, interference with disinfection, and propagation of water pathogens. Finally, monitoring of wells in the aftermath of historical floods, revealed water pathogen contamination, despite shock chlorination, and failures in pathogen detection using conventional water testing practices. CONCLUSIONS:The facts presented, support the need to address vulnerabilities in water regulations, oversight, infrastructure, testing, treatment, and exposure reduction strategies. Ultimately, vulnerable communities that are served by private wells or small rural water systems need low­cost autonomous water treatment solutions in order to prepare for threats they will inevitably face from anticipated climate impacts and infrastructure failures. KEYWORDS: Drinking water, climate change, iron, lead, water pathogens, infrastructure

Background:Private wells are an important source of drinking water in Kewaunee County, Wisconsin. Due to the region’s fractured dolomite aquifer, these wells are vulnerable to contamination by human and zoonotic gastrointestinal pathogens originating from land-applied cattle manure and private septic systems.Objective:We determined the magnitude of the health burden associated with contamination of private wells in Kewaunee County by feces-borne gastrointestinal pathogens.Methods:This study used data from a year-long countywide pathogen occurrence study as inputs into a quantitative microbial risk assessment (QMRA) to predict the total cases of acute gastrointestinal illness (AGI) caused by private well contamination in the county. Microbial source tracking was used to associate predicted cases of illness with bovine, human, or unknown fecal sources.Results:Results suggest that private well contamination could be responsible for as many as 301 AGI cases per year in Kewaunee County, and that 230 and 12 cases per year were associated with a bovine and human fecal source, respectively. Furthermore, Cryptosporidium parvum was predicted to cause 190 cases per year, the most out of all 8 pathogens included in the QMRA.Discussion:This study has important implications for land use and water resource management in Kewaunee County and informs the public health impacts of consuming drinking water produced in other similarly vulnerable hydrogeological settings. https://doi.org/10.1289/EHP7815

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.

The burden of acute gastrointestinal illness (AGI) attributable to natural water recreation in Canada is unknown. Understanding the burden can help prioritize public health interventions and resource allocation for reduction of disease. Our objectives were to compile estimates of AGI burden associated with natural water recreation, identify knowledge gaps in water recreation epidemiology, and evaluate methods applicable for developing a burden estimate for Canada. We conducted a scoping review of the literature. From a total of 2752 unique records identified, 35 met eligibility for inclusion. Articles were chosen if they examined burden in natural waterways, were written in English, and were based in countries of similar economic status to Canada in non-tropical regions. Burden was defined as either: incidence or prevalence, disability-adjusted life years (DALYs), quality-adjusted life years (QALYs), or economic cost. Swimming or wading were the predominant forms of recreation examined (n = 32/35; 91.4%). Waterways studied were primarily marine or coastal beaches (n = 24/35; 68.6%) and were located within or adjacent to urban areas (n = 29/35; 82.9%). The most common indicator for burden was incidence or prevalence (n = 30/35; 85.7%). Prospective cohort studies (n = 17/35; 48.6%) and predictive modelling based on microorganism concentrations (n = 9/35; 25.7%) were the most common methods of estimation. The review highlighted several knowledge gaps regarding recreational waterborne disease burden. Freshwater recreation, rural waterways, and recreational activities other than swimming and wading require further study. We propose that quantitative microbial risk assessment may be an appropriate, cost-effective method to estimate recreational waterborne disease burden in Canada.

Under a changing climate, droughts are projected to increase in frequency and duration in the Southwestern USA. Between 2012 and 2016, California experienced one of the region’s worst droughts, with record high temperatures and low snowpack, runoff, and precipitation. This study documents small drinking water system managers’ experiences during the 2012–2016 Drought. We contribute to research on water system drought resilience by elevating small drinking water system manager perspectives and expertise. We are especially focused on small systems that are not reliant on imports from state or federal water projects. A mixed-method approach ensures each data collection period informs the next to gather statewide perspectives and experiences of managers.Based on an analysis of drinking water manager reflections, the types of impacts, responses, and barriers differed based on both system size and water source portfolio. Common disadvantages that hinder small drinking water systems’ drought resilience and, similarly, climate adaptation include staff and administrative capacity; the financial burden of promoting water conservation over revenue compounded by onerous reporting and funding support programs; consumer awareness challenges; and challenges to consolidation from both local political differences and physical limitations. Systems that built technical, managerial, or financial capacity prior to the Drought were at an advantage over systems that lacked this capacity. In the long term, we found a dearth of adaptation planning among small water systems. Documentation of experiences from the 2012–2016 Drought can inform future planning for droughts and more broadly highlight needs for climate adaptation.

Motivating the formation of partnerships by small water systems

Water is conveyed to consumers through systems that generally rely heavily on energy. The dependence on energy is a major challenge to utility providers because of frequent variation in energy prices. This paper assesses the effect of energy price changes on the financial sustainability of water facilities. It further investigates the proportion of energy cost to total costs of water supply. The study is based on a field survey that targeted five small town water systems and 15 water systems existing under the urban water sector in the Greater Accra and Ashanti regions of Ghana. The results show that energy (diesel and electricity) expenditure forms substantial component of water supply cost. The proportions of energy to total supply costs for small town and urban water systems are 31% and 29%, respectively. The total operational costs per water supply stand at 1.19 US$/m3 and 0.44 US$/m3 for small town and urban water systems respectively. The energy costs per water supply for small town and urban water systems are 0.40 US$/m3 and 0.13 US$/m3, respectively. Results further show that diesel-driven water systems are more sensitive to energy price changes than those of electricity-driven systems; therefore making financial profit from diesel-driven systems is highly elastic to diesel price changes. The results thus indicate that urban water systems are more efficient than small town water systems in terms of both energy and operational costs.

Data from this study could be useful for shaping statewide or national restructuring policies.Physically interconnecting small water systems with larger ones or creating networks of shared management and other expertise might provide a long‐term solution to the problems facing small water systems. Using a geographic information system to display results and screen for geographic barriers, the authors analyzed restructuring potential in 17 states by calculating distances between small and nearby larger water systems and applied screening criteria to indicate whether the restructuring option would be cost‐effective. Physical interconnection with a large system may be economically feasible for up to 35 percent of small community water systems, although in most states examined it would be cost‐effective for only 10–20 percent of them based on the criteria used here. However, the potential for large systems to provide satellite services to small systems is high in the states evaluated. These results cannot be used to implement any particular restructuring option, but they provide insight into overall restructuring potential.

Very small drinking water systems in the United States can face challenges in complying with the Safe Drinking Water Act, resulting in a need to improve existing infrastructure. This study applied a triple bottom-line approach to compare modeled health, environmental, and economic impacts of improving existing centralized water treatment systems to using point-of-use/point-of-entry (POU/POE) devices in four very small community water systems (CWS) serving 40–450 people. We found that POU/POE systems could be implemented 1–3 years faster than centralized improvements and achieve higher removal efficiencies (up to 99% removal for arsenic, compared to 80% for some centralized options), resulting in larger decreases in human exposure to arsenic or nitrate. Treatment options using adsorptive media or ion exchange resins had larger overall environmental impacts than reverse osmosis devices, and the total 30 year cost of POUs/POEs were more expensive in 3 of the 4 modeled systems than centralized improvements due to high replacement frequencies and populations. An ‘ideal’ option in each CWS was not selected; rather, we contextualized our results as tradeoffs.

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

Among all the organic disinfection by-products (DBPs), only trihalomethanes (THMs) and haloacetic acids (HAAs) are regulated in drinking water, while most DBPs are not. Very little information exists on the occurrence of non-regulated DBPs, particularly in small water systems (SWS). Paradoxically, SWS are more vulnerable to DBPs because of a low capacity to implement adequate treatment technologies to remove DBP precursors. Since DBP analyses are expensive, usually SWS have difficulties to implement a rigorous characterization of these contaminants. The purpose of this study was to estimate non-regulated DBP levels in SWS from easy measurements of relevant parameters regularly monitored. Since no information on non-regulated DBPs in SWS was available, a sampling program was carried out in 25 SWS in two provinces of Canada. Five DBP families were investigated: THMs, HAAs, haloacetonitriles (HANs), halonitromethanes (HNMs), and haloketones (HKs). Multivariate linear mixed regression models were developed to estimate HAN, HK, and HNM levels from water quality characteristics in the water treatment plant, concentrations of regulated DBPs, and residual disinfectant levels. The models obtained have a good explanatory capacity since R 2 varies from 0.77 to 0.91 according to compounds and conditions for application (season and type of treatment). Model validation with an independent database suggested their ability for generalization in similar SWS in North America.

ABSTRACT. A rationale is set forth for requiring and/or encouraging the consolidation or regionalization of all systems beneath certain population size levels based on the small water systems’ capability to produce an adequate supply of safe drinking water at a reasonable cost to customers. Estimates for basic costs of water service including personnel, other operation and maintenance and capital are made and a range of water rates is suggested based on reasonableness and acceptability to customers. Guidelines are then drawn for a moderate rate of $10.00 per month and an upper limit rate of $15.00 per month to show the sizes at which public water systems might be expected to achieve fiscal viability. Finally, recommendations are made to State and Federal governmental agencies concerning possible legislation, plans and programs to achieve better public water service through the regionalization or consolidation of small public water systems.