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Background: Escherichia coli O157:H7 is one cause of acute bacterial gastroenteritis, which can be devastating in outbreak situations. We studied the risk of cardiovascular disease following such an outbreak in Walkerton, Ontario, in May 2000. Methods: In this community-based cohort study, we linked data from the Walkerton Health Study (2002-2008) to Ontario's large healthcare databases. We included 4 groups of adults: 3 groups of Walkerton participants (153 with severe gastroenteritis, 414 with mild gastroenteritis, 331 with no gastroenteritis) and a group of 11 263 residents from the surrounding communities that were unaffected by the outbreak. The primary outcome was a composite of death or first major cardiovascular event (admission to hospital for acute myocardial infarction, stroke or congestive heart failure, or evidence of associated procedures). The secondary outcome was first major cardiovascular event censored for death. Adults were followed for an average of 7.4 years. Results: During the study period, 1174 adults (9.7%) died or experienced a major cardiovascular event. Compared with residents of the surrounding communities, the risk of death or cardiovascular event was not elevated among Walkerton participants with severe or mild gastroenteritis (hazard ratio [HR] for severe gastroenteritis 0.74, 95% confidence interval [CI] 0.38-1.43, mild gastroenteritis HR 0.64, 95% CI 0.42-0.98). Compared with Walkerton participants who had no gastroenteritis, risk of death or cardiovascular event was not elevated among participants with severe or mild gastroenteritis. Interpretation: There was no increase in the risk of cardiovascular disease in the decade following acute infection during a major E. coli O157:H7 outbreak. [ABSTRACT FROM AUTHOR]

Background: Following bacterial contamination of a municipal water system in the rural town of Walkerton, Ontario, over 2,300 cases of acute gastroenteritis were documented. The Walkerton Health Study is currently underway to assess for long-term health sequelae among consenting inhabitants of Walkerton, related to the original outbreak. We explored whether the association between the acute exposure and preliminary long-term health outcomes may have been biased through differences between early- and late-recruited study participants. Methods: Using multiple data sources, including the 1996 and 2001 Canadian Census, and records from the Regional Health Unit, hospital and Walkerton Health Study, we determined both sample representativeness and the anticipated effects of intensifying study participant recruitment. Selection bias was assessed by examining for differences between initial and late participants, and their subsequent risk of having hypertension, proteinuria and reduced renal clearance. Results: Of the 4,315 participants, 2,756 were permanent residents of Walkerton, representing 55% of the town's total population. The sample was demographically similar to the population of interest, although statistically women were more likely to participate than men (55% of sample were women compared to 52% of population, p<0.01), and the proportion of both young and very elderly adults was smaller than expected (13% of sample were ≤65 years of age compared to 18% of population, p<0.01). Comparing the initial 3,959 participants to the 356 persons additionally recruited with substantial effort, the latter were more likely to be free of symptoms during the outbreak (21% vs. 7%, p<0.001), but were otherwise similar in terms of age, sex, the use of medical care resources and underlying health state predating the outbreak. The risk of long-term hypertension or renal sequelae did not significantly differ between initial and late study recruits. Conclusions: Participants in the Walkerton Health Study represent the population of interest, and comprise those who were acutely ill during the infected water outbreak. The available study sample should provide reasonably unbiased estimates of the associated risk between acute bacterial gastroenteritis and long-term health sequelae. [ABSTRACT FROM AUTHOR]

As part of a community screening study to assess the long-term health outcomes among residents of Walkerton, Ontario, after contamination of its municipal water supply by Escherichia coli O157:H7 and Campylobacter in 2000, we identified 100 adults who had proteinuria and polyuria but no medical history or medication use to explain their condition. Fifty-six of the 100 participants underwent both initial and confirmatory urine concentration tests, which showed that their urine osmolality could reach normal levels. We then instructed them to reduce their fluid intake to less than 2 L/d for 1 week. The proteinuria and polyuria were largely reversed by this manoeuvre. We do not know at this time whether the proteinuria associated with excessive fluid intake in these otherwise healthy people will affect their kidney function in the long term. [ABSTRACT FROM AUTHOR]

The article focuses on a study which investigates the long term risk for hypertension and renal impairment following gastroenteritis due to Escherichia coli 0157:H7- and Campylobacter-contaminated drinking water. The study included 1,977 adults from Walkerton, Ontario who were followed from 2002 to 2008. Of the total participants, 54 percent reported acute gastroenteritis, with 697 having developed hypertension. Study authors concluded that adults who experienced gastroenteritis during an outbreak are more likely to have increased risk of hypertension.