Epidemiology and Infection

Swimming-associated haemorrhagic colitis due to Escherichia coli O157[ratio]H7 infection: evidence of prolonged contamination of a fresh water lake 1

D. ACKMAN a1a2, S. MARKS a3, P. MACK a3, M. CALDWELL a3, T. ROOT a4 and G. BIRKHEAD a2a5
a1 The Epidemiology Program Office and the Epidemic Intelligence Service, Division of Field Epidemiology, Centers for Disease Control and Prevention, Atlanta, GA
a2 Bureau of Communicable Disease Control, Office of Public Health, New York State Department of Health, Albany, NY
a3 Dutchess County Department of Health, Poughkeepsie, NY
a4 Wadsworth Center, New York State Department of Health, Albany, NY
a5 School of Public Health, University at Albany, State University of New York, Albany, NY


We describe an Escherichia coli O157[ratio]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[ratio]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 [RR]=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[ratio]H7.

(Accepted February 1 1997)

Author for correspondence: D. Ackman, Bureau of Communicable Disease Control, New York State Department of Health, Room 651 Corning Tower, Albany, NY 12237.


1 Presented in part at the 35th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), Sept. 17–20, 1995, San Francisco, CA.