Foodborne Infection Associated with Cross-contamination: Outbreak in Seoul in 2017.

BACKGROUND

In July 2017, there was an outbreak of infection in three auxiliary police squads in Seoul, Korea. An epidemiological investigation was conducted to identify the cause and source of the illness.

MATERIALS AND METHODS

A retrospective cohort study of all members of the three auxiliary police squads was conducted. Self-administered questionnaires were distributed to all members of the three squads and the food handlers. Rectal swabs were collected from symptomatic police and food handlers.

RESULTS

The overall attack rate was 20.4%, and the epidemic curve indicated a point source type outbreak. Of the 257 auxiliary policemen who consumed the incriminated lunch, 55 met the case definition. Of 36 rectal swabs, 10 were positive for and had the same pulsed-field gel electrophoresis pattern. The major symptoms were loose stool (100%) and abdominal pain (59.3%); the median incubation period was 69 hours. In the univariate epidemiological analysis, watermelon (relative risk [RR], 5.75; 95% confidence interval [CI], 2.14-15.43), half-cut chicken soup (RR, 3.96; 95% CI, 1.49-10.54), steamed rice with millet (RR, 2.73; 95% CI, 1.29-5.77), and radish kimchi (RR, 2.57; 95% CI, 1.45-4.55) were positively associated with the illness. Inspection of the food service facility found that the drainpipe under the meat cleaning sink did not work.

CONCLUSION

This outbreak could have been caused by cross-contamination with from raw chicken via environmental sources.