Epidemiology and Infection

An outbreak of Escherichia coli O157[ratio]H7 infections and haemolytic uraemic syndrome associated with consumption of unpasteurized apple cider

E. D. HILBORN a1c1, P. A. MSHAR a2, T. R. FIORENTINO a3, Z. F. DEMBEK a2, T. J. BARRETT a4, R. T. HOWARD a5 and M. L. CARTTER a2
a1 Centers for Disease Control and Prevention, Epidemiology Program Office, Atlanta, Georgia, USA
a2 Connecticut Department of Public Health, Epidemiology Program, Hartford, Connecticut, USA
a3 Connecticut Emerging Infectious Program, Yale University School of Public Health, New Haven, Connecticut, USA
a4 National Center for Infectious Disease, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
a5 Connecticut Department of Public Health, Laboratory Division, Hartford, Connecticut, USA


During October 1996, an outbreak of Escherichia coli O157[ratio]H7 infections among Connecticut residents occurred. An epidemiologic investigation included enhanced surveillance and a case-control study. Clinical isolates of Escherichia coli O157[ratio]H7 were typed by pulsed-field gel electrophoresis (PFGE). Implicated cider samples were analysed by culture and polymerase chain reaction (PCR). Consumption of implicated cider was associated with illness; (matched odds ratio = undefined, 95% confidence interval = 3·5–infinity). Ultimately, a total of 14 outbreak-associated patients were identified. All isolates analysed by PFGE yielded the outbreak-associated subtype. Escherichia coli O157[ratio]H7 was not cultured from three cider samples; PCR analysis detected DNA fragments consistent with Escherichia coli O157[ratio]H7 in one. This outbreak was associated with drinking one brand of unpasteurized apple cider. PFGE subtyping supported the epidemiologic association. PCR analysis detected microbial contaminants in the absence of live organisms. Washing and brushing apples did not prevent cider contamination.

(Accepted September 23 1999)

c1 Author for correspondence: U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Mail Drop 58A, Research Triangle Park, North Carolina 27711, USA.