Search

Background Children may be at higher risk for swimming-associated illness following exposure to fecally-contaminated recreational waters. We analyzed a pooled data set of over 80,000 beachgoers from 13 beach sites across the United States to compare risks associated with the fecal indicator bacteria Enterococcus spp. (measured by colony forming units, CFU and quantitative polymerase chain reaction cell equivalents, qPCR CE) for different age groups across different exposures, sites and health endpoints. Methods Sites were categorized according to the predominant type of fecal contamination (human or non-human). Swimming exposures of varying intensity were considered according to degree of contact and time spent in the water. Health endpoints included gastrointestinal and respiratory symptoms and skin rashes. Logistic regression models were used to analyze the risk of illness as a function of fecal contamination in water as measured by Enterococcus spp. among the exposed groups. Non-swimmers (those who did not enter the water) were excluded from the models to reduce bias and facilitate comparison across groups. Results Gastrointestinal symptoms were the most sensitive health endpoint and strongest associations were observed with Enterococcus qPCR CE at sites impacted by human fecal contamination. Under several exposure scenarios, associations between illness and Enterococcus spp. levels were significantly higher among children compared to adolescents and adults. Respiratory symptoms were also associated with Enterococcus spp. exposures among young children at sites affected by human fecal sources, although small sample sizes resulted in imprecise estimates for these associations. Conclusion Under many exposure scenarios, children were at higher risk of illness associated with exposure to fecal contamination as measured by the indicator bacteria Enterococcus spp. The source of fecal contamination and the intensity of swimming exposure were also important factors affecting the association between Enterococcus spp. and swimming-associated illness. [ABSTRACT FROM AUTHOR]

Objectives. To provide summary estimates of gastroenteritis risks and illness burden associated with recreational water exposure and determine whether children have higher risks and burden. Methods. We combined individual participant data from 13 prospective cohorts at marine and freshwater beaches throughout the United States (n = 84 411). We measured incident outcomes within 10 days of exposure: diarrhea, gastrointestinal illness, missed daily activity (work, school, vacation), and medical visits. We estimated the relationship between outcomes and 2 exposures: body immersion swimming and Enterococcus spp. fecal indicator bacteria levels in the water. We also estimated the population-attributable risk associated with these exposures. Results. Water exposure accounted for 21% of diarrhea episodes and 9% of missed daily activities but was unassociated with gastroenteritis leading to medical consultation. Children aged 0 to 4 and 5 to 10 years had the most water exposure, exhibited stronger associations between levels of water quality and illness, and accounted for the largest attributable illness burden. Conclusions. The higher gastroenteritis risk and associated burden in young children presents important new information to inform future recreational water quality guidelines designed to protect public health. [ABSTRACT FROM AUTHOR]

The United States Environmental Protection Agency is committed to developing new recreational water quality criteria for coastal waters by 2012 to provide increased protection to swimmers. We review the uncertainties and shortcomings of the current recreational water quality criteria, describe critical research needs for the development of new criteria, as well as recommend a path forward for new criteria development. We believe that among the most needed research needs are the completion of epidemiology studies in tropical waters and in waters adversely impacted by urban runoff and animal feces, as well as studies aimed to validate the use of models for indicator and pathogen concentration and health risk predictions. [ABSTRACT FROM AUTHOR]

During the Escherichia coli O157:H7 outbreak in 2006 in the United States, the primary strategy to prevent illness was to advise consumers not to eat spinach. No widespread warnings were issued about preventing person-to-person (secondary) transmission. A disease transmission model, fitted to the current data, was used to investigate likely reductions in illnesses that could result from interventions to prevent secondary transmission. The model indicates that exposure to contaminated spinach occurred early in the outbreak and that secondary transmission was similar to that in previous E. coli outbreaks (≈12%). The model also suggests that even a modestly effective strategy to interrupt secondary transmission (prevention of only 2%-3% of secondary illnesses) could result in a reduction of ≈5%-11% of symptomatic cases. This analysis supports the use of widespread public health messages during outbreaks of E. coli O157:H7 with specific advice on how to interrupt secondary transmission. [ABSTRACT FROM AUTHOR]

Risk assessments and intervention trials have been used by the U.S. Environmental Protection Agency to estimate drinking water health risks. Seldom are both methods used concurrently. Between 2001 and 2003, illness data from a trial were collected simultaneously with exposure data, providing a unique opportunity to compare direct risk estimates of waterborne disease from the intervention trial with indirect estimates from a risk assessment. Comparing the group with water treatment (active) with that without water treatment (sham), the estimated annual attributable disease rate (cases per 10,000 persons per year) from the trial provided no evidence of a significantly elevated drinking water risk [attributable risk = -365 cases/year, sham minus active; 95% confidence interval (CI), -2,555 to 1,825]. The predicted mean rate of disease per 10,000 persons per person-year from the risk assessment was 13.9 (2.5, 97.5 percentiles: 1.6, 37.7) assuming 4 log removal due to viral disinfection and 5.5 (2.5, 97.5 percentiles: 1.4, 19.2) assuming 6 log removal. Risk assessments are important under conditions of low risk when estimates are difficult to attain from trials. In particular, this assessment pointed toward the importance of attaining site-specific treatment data and the clear need for a better understanding of viral removal by disinfection. Trials provide direct risk estimates, and the upper confidence limit estimates, even if not statistically significant, are informative about possible upper estimates of likely risk. These differences suggest that conclusions about waterborne disease risk may be strengthened by the joint use of these two approaches. [ABSTRACT FROM AUTHOR]

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. We believe this preliminary estimate should be updated as new data become available. [ABSTRACT FROM AUTHOR]

Although immunocompromised persons may be at increased risk for gastrointestinal illnesses, no trials investigating drinking water treatment and gastrointestinal illness in such patients have been published. Earlier results from San Francisco suggested an association (OR 6.76) between tap water and cryptosporidiosis among HIV + persons. The authors conducted a randomized, triple-blinded intervention trial of home water treatment in San Francisco, California, from April 2000 to May 2001. Fifty HIV-positive patients were randomized to externally identical active (N = 24) or sham (N = 26) treatment devices. The active device contained a filter and UV light; the sham provided no treatment. Forty-five (90%) of the participants completed the study and were successfully blinded. Illness was measured using `highly credible gastrointestinal illness' (HCGI), a previously published measure. There were 31 episodes of HCGI during 1,797 person-days in the sham group and 16 episodes during 1,478 person-days in the active group. The adjusted relative risk was 3.34 (95% Cl: 0.99-11.21) times greater in those with the sham device. The magnitude of the point estimate of the risk, its consistency with recently published observational data, and its relevance for drinking water choices by immunocompromised individuals support the need for larger trials. [ABSTRACT FROM AUTHOR]

Severe flooding occurred in the midwestern United States in 2001. Since November 2000, coincidentally, data on gastrointestinal symptoms had been collected for a drinking water intervention study in a community along the Mississippi River that was affected by the flood. After the flood had subsided, the authors asked these subjects (n = 1,110) about their contact with floodwater. The objectives of this investigation were to determine whether rates of gastrointestinal illness were elevated during the flood and whether contact with floodwater was associated with increased risk of gastrointestinal illness. An increase in the incidence of gastrointestinal symptoms during the flood was observed (incidence rate ratio = 1.29, 95% confidence interval: 1.06, 1.58), and this effect was pronounced among persons with potential sensitivity to infectious gastrointestinal illness. Tap water consumption was not related to gastrointestinal symptoms before, during, or after the flood. An association between gastrointestinal symptoms and contact with floodwater was also observed, and this effect was pronounced in children. This appears to be the first report of an increase in endemic gastrointestinal symptoms in a longitudinal cohort prospectively observed during a flood. These findings suggest that severe climatic events can result in an increase in the endemic incidence of gastrointestinal symptoms in the United States. [ABSTRACT FROM AUTHOR]

Despite numerous studies, uncertainty remains about how water quality indicators can best be used in the regulation of recreational water. We conducted a systematic review of this topic with the goal of quantifying the association between microbial indicators of recreational water quality and gastrointestinal (GI) illness. A secondary goal was to evaluate the potential for Gl illness below current guidelines. We screened 976 potentially relevant studies and from these identified 27 studies. From the latter, we determined summary relative risks for Gl illness in relation to water quality indicator density. Our results support the use of enterococci in marine water at U.S. Environmental Protection Agency guideline levels. In fresh water, Escherichia coli was a more consistent predictor of GI illness than are enterococci and other bacterial indicators. A log (base 10) unit increase in enterococci was associated with a 1.34 [95% confidence intervals (CI), 1.00-1.75] increase in relative risk in marine waters, and a log (base 10) unit increase in E. coli was associated with a 2.12 (95% CI, 0.925-4.85) increase in relative risk in fresh water. Indicators of viral contamination were strong predictors of GI illness in both fresh and marine environments. Significant heterogeneity was noted among the studies. In our analysis of heterogeneity, studies that used a non-swimming control group, studies that focused on children, and studies of athletic or other recreational events found elevated relative risks. Future studies should focus on the ability of new, more rapid and specific microbial methods to predict health effects, and estimating the risks of recreational water exposure among susceptible persons. [ABSTRACT FROM AUTHOR]

Approximately 1,100 communities in the United States have combined sewer and stormwater systems whose capacity may be exceeded during moderate or heavy rainfall. Outflows may occur that can deposit water with varying concentrations of the components of sewage onto public areas, where contact with residents or workers is possible, potentially resulting in a range of adverse health effects. This study proposes and applies three analytic methods to evaluate the impact of such outflows on public health. [ABSTRACT FROM AUTHOR]