An Epidemiological Investigation on an Outbreak of Shigellosis in a Special School for Handicapped in Yeongcheon-si and in a Rehabilitation Facility in Gyeongsan-si, Korea, 2008

Lee, Hyun Dong; Lee, Soon Ok; Lim, Hyun Sul

Abstract

OBJECTIVES
In September 2008, an outbreak of diarrhea occurred among students attending Y school in Yeongcheon-si. Shigella sonnei was cultured from some of the rectal swabs. An epidemiological investigation was carried out to determine the source of the infection and the mode of transmission of the shigellosis outbreak.
METHODS
The index case lived in the D rehabilitation facility in Gyeongsan-si and an additional epidemiological investigation was carried out there. The cases could not be questioned due to their mental handicaps. The teachers were interviewed instead. A patient case was defined as a resident with diarrhea more than one time a day from September 18 to September 26, 2008 or a resident with confirmed Shigella sonnei at the Y school or the D rehabilitation facility.
RESULTS
The attack rate was 1.2% (8 persons) among 659 persons in the Y school and D rehabilitation facility. Five persons were microbiologically confirmed to have the infection and three persons were diagnosed on the basis of symptoms. Shigella sonnei was cultured from five of the 659 rectal swabs. However, 80 environmental specimens including drinking water, preserved foods, and cooking utensils were negative. All eight patients were Y school students and had been living in group boarding and lodging. Six of them lived in the D rehabilitation facility and two lived in the dormitory at the Y school. Five cases showed pulsed-field gel electrophoresis patterns that were identical for Shigella sonnei.
CONCLUSIONS
The results of this study showed that the infection source of the shigellosis outbreak, in the two places, were identical. It is likely that the infections initially spread from a teacher or volunteer and then among the students.