An Outbreak of Escherichia coli O157:H7 Infections Associated with Leaf Lettuce Consumption

• Published in: The Journal of infectious diseases Vol. 177; no. 6; pp. 1588 - 1593
• Main Authors: Ackers, Marta-Louise, Mahon, Barbara E., Leahy, Ellen, Goode, Brant, Damrow, Todd, Hayes, Peggy S., Bibb, William F., Rice, Daniel H., Barrett, Timothy J., Hutwagner, Lori, Griffin, Patricia M., Slutsker, Laurence
• Format: Journal Article
• Language: English
• Published: Chicago, IL The University of Chicago Press 01-06-1998; University of Chicago Press
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Animals; Bacterial diseases; Bacterial diseases of the digestive system and abdomen; Biological and medical sciences; Case-Control Studies; Cattle; Child; Child, Preschool; Disease Outbreaks; Epidemiologic Methods; Escherichia coli Infections - epidemiology; Escherichia coli Infections - etiology; Escherichia coli Infections - physiopathology; Escherichia coli O157; Female; Human bacterial diseases; Humans; Infectious diseases; Lactuca - poisoning; Lipopolysaccharides - blood; Lipopolysaccharides - immunology; Male; Medical sciences; Middle Aged; Plant Leaves; Sheep; Consumption; Epidemic; Hemolysis; Escherichia coli; Epidemiology; Case study; Lettuce; Food intake; Food poisoning; Digestive diseases; Bacteria; Biological contamination; Enterobacteriaceae
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1086/515323

In July 1995, 40 Montana residents were identified with laboratory-confirmed Escherichia coli O157:H7 infection; 52 residents had bloody diarrhea without laboratory confirmation. The median age of those with laboratory-confirmed cases was 42 years (range, 4–86); 58% were female. Thirteen patients were hospitalized, and 1 developed hemolytic-uremic syndrome. A case-control study showed that 19 (70%) of 27 patients but only 8 (17%) of 46 controls reported eating purchased (not home-grown) leaf lettuce before illness (matched odds ratio, 25.3; 95% confidence interval, 3.9–1065.6). Pulsed-field gel electrophoresis identified a common strain among 22 of 23 isolates tested. Implicated lettuce was traced to two sources: a local Montana farm and six farms in Washington State that shipped under the same label. This outbreak highlights the increasing importance of fresh produce as a vehicle in foodborne illness. Sanitary growing and handling procedures are necessary to prevent these infections.