Investigating Bacillary Dysentery Outbreaks in Dabang and Shanmei Villages of Alishan Township, Chiayi County

Abstract

The Saint Martin Hospital of Chiayi county reported on 9 April 2001 a bacillary dysentery case of a 66-year old female in Tefuyeh Tribe of Dabang Village, Alishan Township. As there had never been such cases in the last ten some years, a large-scale epidemiological investigation was conducted. The investigation took primarily the forms of case interviews, survey of the residents, review of medical records of all medical care institutions in Alishan Township, and review of student school attendance, and healthcare records at schools. Surveillance stations for diarrhea patients were set up at the same time at the Alishan Health Station, medical units of the Saint Martin Hospital, the Chiayi Christian Hospital, the Wang FF Clinic, the Wang CL clinic, the Dabang Primary School, the Sanmei Primary School, and the Dabang and Sanmei nurseries. Any individuals with two or more diarrhea in a day should be reported immediately and their rectal specimens collected for laboratory testing. These measures were taken to detect suspected cases. The epidemiological survey described the date of onset of each case, their distribution and their personal and geographic relationship to disclose the possible causes of infection and route of transmission. Between the first confirmed case in Dabang on 9 April till 7 June, 82 cases had been identified (10 confirmed cases, one asymtomatic positive case, and 34 suspects in Dabang, and 14 confirmed cases and 23 suspects in Shanmei). The first case in Dabang became ill on 31 March. The first case in Shanmei became ill on 22 April and her grandmother is a sister of the first case of Dabang. She had visited the case in Dabang. As all cases were related through personal contacts, time of onset and geographically, it was decided that the present bacillary dysentery outbreaks were brought about by person-to-person contacts. It was, however, not possible to decide when and where the outbreaks broke out. By the medical records of the residents, bacillary dysentery did occur in the past, but was in most cases treated as gastrointestinal infections. The outbreaks concluded on 24 May when the last case was detected. A special feature of this investigation was that all cases were, with the exception of the first case which was reported by the hospital, identified by the health and medical care institutions at all levels through surveillance, symptom reporting, and immediate investigation. Control measures taken at the same time effectively prevented the spread of the infection to other parts of Alishan Township.