[An epidemiological study on an outbreak of Escherichia coli O157:H7 infection]

We conducted an epidemiological study on an outbreak of Escherichia coli (E. coli) O157:H7 to reveal the food vehicle for E. coli O157:H7. An approach of descriptive and analytical epidemiology was conducted on the basis of a case definition, that is workers reported the onset of diarrhea in between July 15 and July 22, 1996. There were 47 workers including five patients who had stool cultures that yielded E. coli O157:H7. A case-control study of all workers who dined at the company cafeteria during the 8 days probable exposure period was conducted using cafeteria computer records. Eating in the cafeteria on July 11 or 12 was associated with illness. Further case-control study using a self-administered questionnaire revealed that eating radish sprout salad on July 11 was the only food item slightly associated with diarrhea. Since the epidemiological study could reveal the cause of the outbreak of E. coli O157:H7, it should be used more and properly in collaboration with epidemiologists.