The Sonoma Water Evaluation Trial: A Randomized Drinking Water Intervention Trial to Reduce Gastrointestinal Illness in Older Adults (original) (raw)
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Emerging Infectious Diseases, 2002
We conducted a randomized, triple-blinded home drinking water intervention trial to determine if a large study could be undertaken while successfully blinding participants. Households were randomized 50:50 to use externally identical active or sham treatment devices. We measured the effectiveness of blinding of participants by using a published blinding index in which values >0.5 indicate successful blinding. The principal health outcome measured was Ahighly credible gastrointestinal illness@ (HCGI). Participants (n=236) from 77 households were successfully blinded to their treatment assignment. At the end of the study, the blinding index was 0.64 (95% confidence interval 0.51-0.78). There were 103 episodes of HCGI during 10,790 person-days at risk in the sham group and 82 episodes during 11,380 person-days at risk in the active treatment group. The incidence rate ratio of disease (adjusted for the clustered sampling) was 1.32 (95% CI 0.75, 2.33) and the attributable risk was 0.24 (95% CI -0.33, 0.57). These data confirm that participants can be successfully blinded to treatment group assignment during a randomized trial of an in-home drinking water intervention.
Journal of Water and Health, 2006
The incidence of acute gastrointestinal illness (AGI) attributable to public drinking water systems in the United States cannot be directly measured but must be estimated based on epidemiologic studies and other information. The randomized trial is one study design used to evaluate risks attributable to drinking water. In this paper, we review all published randomized trials of drinking water interventions in industrialized countries conducted among general immunocompetent populations. We then present an approach to estimating the incidence (number of cases) of AGI attributable annually to drinking water. To develop a national estimate, we integrate trial results with the estimated incidence of AGI using necessary assumptions about the estimated number of residents consuming different sources of drinking water and the relative quality of the water sources under different scenarios. Using this approach we estimate there to be 4.26-11.69 million cases of AGI annually attributable to public drinking water systems in the United States.
International Journal of Environmental Health Research, 1997
The objective of this study was to assess if drinking water meeting currently accepted microbiological standards is the source of gastrointestinal illnesses and to attempt to identify the source(s) of these illnesses. A randomized prospective study was conducted over a period of 16 months (September 1993 ±December 1994 in a middle class suburban community served by a single water filtration plant. A representative sample of 1400 families were selected and randomly allocated in four groups of 350, to the following regimens: (1) tap water; (2) tap water from a continuously purged tap; (3) bottled plant water; (4) purified bottled water (tap water treated by reverse osmosis or spring water). The water treatment plant produced wather that met or exceeded current North American regulations for drinking water quality. The distribution system was found to be in compliance for both coliforms and chlorine. Using the purified water group as the baseline, the excess of gastrointestinal illness associated with tap water was 14% in the tap group and 19% in the tap-valve group. Children 2 ±5 years old were the most affected with an excess of 17% in the tap group and 40% in the tap-valve group. Mottled plant water was not the source of any increase in the incidence of gastrointestinal illnesses, even if it contained very high levels of heterotrophic bacteria after two weeks. The data collected suggest that 14 ±40% of the gastrointestinal illnesses are attributable to tap water meeting current standards and that the water distribution system appears to be partly responsible for these illnesses.
The American journal of tropical medicine and hygiene, 2007
We evaluated enteric infection serology as an alternative outcome measure to diarrhea prevalence in a randomized controlled trial of household-based drinking water treatment; 492 households were randomly assigned to 5 household-based water treatment interventions or control. Individuals were followed weekly over 52 weeks to measure diarrhea prevalence. Study subjects of age <or= 6 months and < 24 months had blood drawn at entry and exit from the study or age cohort. Serologic assays for Cryptosporidium parvum, Giardia intestinalis, enterotoxigenic Escherichia coli (ETEC), and Norovirus were done. Of 343 subjects eligible for the study, the proportions of subjects experiencing serologic responses were 56% for Norovirus, 24% for C. parvum, 10% for ETEC, and 16% for G. intestinalis. Serologic response was associated with increased diarrhea prevalence only for G. intestinalis (P = 0.0134). Serologic response to the antigens tested for G. intestinalis but not for Norovirus, C. parv...
Water research, 2014
We used a Poisson regression to compare daily hospital admissions of elderly people for acute gastrointestinal illness in Boston against daily variations in drinking water quality over an 11-year period, controlling for weather, seasonality and time trends. The Massachusetts Water Resources Authority (MWRA), which provides non-filtered water to 1.5 million people in the greater Boston area, changed its disinfection method from chlorination to ozonation during the study period so we were also able to evaluate changes in risk associated with the change in disinfection method. Other available water quality data from the MWRA included turbidity, fecal coliforms, UV-absorbance, and planktonic algae and cyanobacteriae concentrations. Daily weather, rainfall data and water temperature were also available. Low water temperature, increases in turbidity and, to a lesser extent, in fecal coliform and cyanobacteriae were associated with a higher risk of hospital admissions, while the shift from...
PloS one, 2016
Community water supplies in underserved areas of the United States may be associated with increased microbiological contamination and risk of gastrointestinal disease. Microbial and health risks affecting such systems have not been systematically characterized outside outbreak investigations. The objective of the study was to evaluate associations between self-reported gastrointestinal illnesses (GII) and household-level water supply characteristics. We conducted a cross-sectional study of water quality, water supply characteristics, and GII in 906 households served by 14 small and medium-sized community water supplies in Alabama's underserved Black Belt region. We identified associations between respondent-reported water supply interruption and any symptoms of GII (adjusted odds ratio (aOR): 3.01, 95% confidence interval (CI) = 1.65-5.49), as well as low water pressure and any symptoms of GII (aOR: 4.51, 95% CI = 2.55-7.97). We also identified associations between measured wate...
Improvements in diarrheal disease prevalence with pointofuse water filter
Background: There is increasing evidence of the efficacy of point-of-use water filters on diarrhea prevalence in numerous global settings, in both observational studies and randomized experiments. Most studies, however, are focused on rural locations. Here we use self-report household surveys, and select drinking water testing, to monitor a set of approximately 10,000 households receiving Sawyer® point-of-use water filters, WASH training, and Albendazole in Kibera, Kenya. Results: Statistical models accounting for confounding factors estimated 2-week, self-reported prevalence of diarrhea dropping from 52.7% to 2.2% after approximately 70 days of filter use. Field testing characterized most water sources (18 out of 25) as unsafe for Total coliforms, many for E. coli (6 out of 25), and one source above WHO health guidelines for arsenic. There was no evidence of a difference in self-reported diarrhea prevalence between households receiving Albendazole at distribution vs. those that didn’t (p>0.05). Conclusions: The introduction of point of use filters to households in a densely populated informal settlement reduced diarrhea and other health related problems. Future randomized controlled studies with objective health measures are needed to ensure cause-effect impact of the filters, and study of filter longevity in the field continues to be a critical need.