Epidemiology and Infection

Escherichia coli O157[ratio]H7 diarrhoea associated with well water and infected cattle on an Ontario farm

S. G. JACKSON a1c1, R. B. GOODBRAND a1, R. P. JOHNSON a2, V. G. ODORICO a1, D. ALVES a3, K. RAHN a2, J. B. WILSON a4, M. K. WELCH a4 and R. KHAKHRIA a5
a1 Ontario Ministry of Health, Hamilton Public Health Laboratory, Hamilton, Ontario
a2 Health Canada, Health of Animals Laboratory, Guelph, Ontario
a3 Ontario Ministry of Agriculture Food and Rural Affairs, Health Management, Fergus, Ontario
a4 Health Canada, Laboratory Centre for Disease Control, Bureau of Communicable Disease Epidemiology, Ottawa, and Department of Population Medicine, University of Guelph, Guelph, Ontario
a5 Health Canada, Laboratory Centre for Disease Control, Bureau of Microbiology, Ottawa, Ontario


A 16-month old female child living on an Ontario dairy farm was taken to hospital suffering from bloody diarrhoea. Escherichia coli O157[ratio]H7 was isolated from her stool. Initial tests of well water samples were negative for E. coli by standard methods but culture of selected coliform colonies on sorbitol-MacConkey agar led to isolation of E. coli O157[ratio]H7. E. coli O157[ratio]H7 was also isolated from 63% of cattle on the farm. The E. coli O157[ratio]H7 isolates from the child, the water and the cattle were phage type 14, produced verotoxins 1 and 2, and were highly related on analysis by pulsed field gel electrophoresis. The child did not have known direct contact with the cattle and did not consume unpasteurized milk. Hydrogeological investigation revealed the design and location of the well would allow manure-contaminated surface water to flow into the well. This investigation demonstrates that cattle farm well water is a potential source of E. coli O157[ratio]H7 which may not be identified by standard screening for E. coli in water.

(Accepted October 7 1997)

c1 Author for correspondence: Dr S. G. Jackson, Ontario Ministry of Health, Hamilton Public Health Laboratory P.O. Box 2100, Hamilton, ON, Canada, L8N 3R5.