Epidemiological Investigation of A Bacillary Dysentery Outbreak at A Juvenile Correction Institution
1997 Vol.13 NO.12
An incident of group diarrhea occurred at a juvenile correction institution on 6 May 1997. The institution had 106 children at the time, 62 of them had developed symptoms of fever, vomiting, serious diarrhea and bloody stools. Laboratory testings on 8 May confirmed that the incident was caused by Shigella flexneri 2a. By the epidemic curve and the findings of the epidemiological investigation, it was speculated that inter-personal contact was the major route of transmission. The index case was a 13-year old juvenile offender. He had already shown symptoms at the time when he was admitted to the institution on 30 April. The special circumstances of the institution encouraged direct and indirect contact with the source of infection. 60% of the children had been infected in six days. The case was closed in two months on 4 July. During this time, 842 specimens had been collected from 200 some individuals for 96 laboratory testings. The results indicated that 87 shigella strains were isolated and 45 positive cases were identified. Drug susceptibility tests showed that the isolated strains had already developed resistance to nalidixic acid used for treatment. The later-isolated strains even transformed from serotype 2a to y. By plasmid profile and large DNA fragment profile, the source of infection was confirmed to be the index case. The possibility that the strain was originated from Jenai Township of Nantou County was ruled out preliminarily. Cefixime orals were administered on 20 May, and five days later, 10 cases (22%) still discharged the bacterial pathogen. They though were without symptoms, were inapparent carriers. Treatment continued until the last case stopped discharging the pathogen on 4 July. Follow-up continued till 20 August and the investigation was called off when no further cases were reported.