Swimming-associated haemorrhagic colitis due to Escherichia coli O157:H7 infection: evidence of prolonged contamination of a fresh water lake

Epidemiol Infect. 1997 Aug;119(1):1-8. doi: 10.1017/s095026889700770x.


We describe an Escherichia coli O157:H7 outbreak associated with a fresh water lake at a county park. Campers were surveyed for diarrhoeal illness within 10 days of their visit, and a case-control study of day visitors was conducted. A confirmed case was a symptomatic person with a stool culture positive for E. coli O157:H7 and a probable case was a person with bloody diarrhoea. Clinical isolates of E. coli O157 were subtyped by pulsed field gel electrophoresis (PFGE). In the camper survey, 12 (38%) of 32 swimmers had a diarrhoeal illness (relative risk [RR] = 12.4; 95% confidence interval [CI] = 1.7-89.7). For the case-control study, the 12 cases were more likely than controls to have purposefully ingested lake water (odds ratio [OR] = 6.9, 95% CI = 0.9-55.8). The PFGE patterns of six clinical isolates were indistinguishable. This report further demonstrates that contaminated fresh-water lakes can be the source of community outbreaks of E. coli O157:H7.

MeSH terms

  • Adolescent
  • Camping
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Colitis / diagnosis
  • Colitis / epidemiology
  • Colitis / microbiology*
  • Diarrhea / microbiology
  • Electrophoresis, Gel, Pulsed-Field
  • Escherichia coli Infections / diagnosis
  • Escherichia coli Infections / epidemiology*
  • Escherichia coli Infections / transmission
  • Escherichia coli O157*
  • Feces / microbiology
  • Female
  • Humans
  • Infant
  • Male
  • New York / epidemiology
  • Risk Factors
  • Swimming
  • Water Microbiology