THE ROLE OF HEIGHTENED SURVEILLANCE IN AN OUTBREAK OF ESCHERICHIA-COLI O157.H7

After instituting laboratory screening for Escherichia coli O157.H7, a Connecticut hospital isolated the organism from four persons in Septe mber 1993. As a result, an outbreak of E. coli O157.H7 associated with a country club was detected. The club had served hamburger from the s ame shipment at two picnics. Attendees of two picnics were interviewed , stool cultures mere obtained from symptomatic persons, and the remai ning hamburger was cultured. Twenty (22%) of 89 persons who ate hambur ger became ill; compared with 1 of 60 who did not eat hamburger (relat ive risk = 13.5, 95% confidence interval 3.2-56.3). Among persons who ate hamburgers, illness was strongly associated with eating hamburger that was not thoroughly cooked (P < 0.001). All 20 samples from 5 rema ining boxes of patties yielded E. coli O157.H7. Isolates from hamburge r and case-patients mere indistinguishable by pulsed-field gel electro phoresis. Heightened surveillance can rapidly identify outbreaks and m ay mitigate their impact. However, continued review of food safety iss ues is necessary if E. coli O157.H7 outbreaks are to be prevented.