Enterotoxigenic Escherichia coli Outbreak in a High School / 감염과화학요법

BACKGROUND: Enterotoxigenic Escherichia coli (ETEC) has been well known pathogen as a cause of travelers' diarrhea. Nowadays, however, ETEC is also increasingly recognized as the cause of foodborne or waterborne outbreaks. We investigated an outbreak of a high school in Gwangju metropolitan city to trace the source of infection and the mode of transmission of ETEC. MATERIALS AND METHODS: All symptomatic persons were interviewed and filled out the questionnaires. We surveyed their clinical symptoms and the foods that they ate. We checked the facilities of the school, dinning room and water supply system. Microbiologic examination were carried out on above symptomatic persons and many environmental specimens. All gathered samples were examined in Gwangju city Health & Environment Research Institute. ETEC isolates were submitted to Korea Center for Disease Control and Prevention (KCDC) for Pulsed-field gel electrophoresis (PFGE). We also requested water quality analysis of water samples to Waterworks Research Institute. RESULTS: The 39 students and one sibling who visited and ate school meal showed symptoms. All staffs and cooks showed no symptom. Among 51 stool specimens, ETEC was isolated from 19 (18: students, 1:cook). ETEC was also isolated from specimens from a purifier and a water tap of the dinning room and water tank (underground water). In PFGE test, isolates from 18 persons showed identical pattern, but the PFGE patterns from water were different. Isolates of water samples showed different PFGE patterns even within the same sample. Investigation of the water distribution system revealed that contaminated underground water had been supplied to the dinning room and students of the school were exposed to it. CONCLUSION: This is the outbreak of ETEC infection occurred in a high school. Besides students, ETEC was also isolated from water samples. Considering some epidemiologic features, we suspect the mode of transmission may be waterborne despite the inconsistent PFGE results.

Enterotoxigenic Escherichia coli Outbreak in a High School / 감염과화학요법

BACKGROUND: Enterotoxigenic Escherichia coli (ETEC) has been well known pathogen as a cause of travelers' diarrhea. Nowadays, however, ETEC is also increasingly recognized as the cause of foodborne or waterborne outbreaks. We investigated an outbreak of a high school in Gwangju metropolitan city to trace the source of infection and the mode of transmission of ETEC. MATERIALS AND METHODS: All symptomatic persons were interviewed and filled out the questionnaires. We surveyed their clinical symptoms and the foods that they ate. We checked the facilities of the school, dinning room and water supply system. Microbiologic examination were carried out on above symptomatic persons and many environmental specimens. All gathered samples were examined in Gwangju city Health & Environment Research Institute. ETEC isolates were submitted to Korea Center for Disease Control and Prevention (KCDC) for Pulsed-field gel electrophoresis (PFGE). We also requested water quality analysis of water samples to Waterworks Research Institute. RESULTS: The 39 students and one sibling who visited and ate school meal showed symptoms. All staffs and cooks showed no symptom. Among 51 stool specimens, ETEC was isolated from 19 (18: students, 1:cook). ETEC was also isolated from specimens from a purifier and a water tap of the dinning room and water tank (underground water). In PFGE test, isolates from 18 persons showed identical pattern, but the PFGE patterns from water were different. Isolates of water samples showed different PFGE patterns even within the same sample. Investigation of the water distribution system revealed that contaminated underground water had been supplied to the dinning room and students of the school were exposed to it. CONCLUSION: This is the outbreak of ETEC infection occurred in a high school. Besides students, ETEC was also isolated from water samples. Considering some epidemiologic features, we suspect the mode of transmission may be waterborne despite the inconsistent PFGE results.

Epidemiologic Investigation of an Outbreak of Shigellosis in Kyongju, Korea / 예방의학회지

OBJECTIVES: This study was carried out to investigate the sources of infection and modes of transmission of an outbreak of shigellosis that occurred among pupils of "M" primary school and residents near the school in Kyongju from Sept. 24 to Oct. 24, 1998. METHODS: The subjects who completed a questionnaire and a rectal swab for microbiologic examinations were 1,534 persons (781 males, 753 females), including 469 pupils of "M" primary school (268 males, 201 females). Bacteriological examinations of underground water and simple piped water were done. RESULTS: The attack rate of diarrhea was 28.7% in the subjects from Sept. 24 to Oct. 24, 1998. There was no difference in attack rate of diarrhea by gender, but it was significantly higher in the pupils of "M" primary school than others (p<0.01). The attack rate of diarrhea by resident areas was no different to the pupils of "M" primary school, but was significantly higher in the residents of Mohwa 2 Ri except pupils that "M" primary school is located in (p<0.01). The distribution of date of onset revealed the exposure date to be Sept, 22 and 23 in consideration of incubation periods and common source outbreak followed propagative spread in the epidemic curve. The major characteristics of diarrhea were watery (89.1%) in nature, 1~3 days (72.5%) in duration, 2~3 times (63.9%) in frequency. The clinical symptoms among the diarrheal cases included abdominal pain (74.1%), fever (56.4%), headache (55.9%), chill (40.4%) and tenesmus (31.4%). CONCLUSIONS: The source of infection was estimated to be contaminated underground water and simple piped water caused by leakage from the cess pool. It is highly necessary that the management of drinking water and cess pools should be done thoroughly.

An Epidemiological Survey on a Salmonella enteritidis Outbreak in Kyongju, Korea / 한국역학회지

This study was conducted to investigate the cause and magnitude of food poisoning among residents and visitors for a birthday party in a rural area of Kyongju city in september, 1996. The total subjects were 137 persons, 119 residents(53 males, 66 females), including 7 hospitalixed patients and 18 visitors(8 males, 10 females). The investigation consisted of an interview survey, a study on clinical characteristics for the patients hospitalized, bacteriological examinations of the underground water and microbiologic examinations on microbes isolated from the patients. The population at risk was 59 persons(24 males, 35 females). The attack rate was 50.0%(12 cases) for males, 48.6% for females(17 cases). The cases were distributed evenly for all age groups. The attack rates for each party-food and possible fooe groups were not significantly different. Most clinical symptoms were significantly more frequent among cases than non-ases: abdominal pain(73.1%), diarrhea(73.1%), chilliness(69.2%), fever(65.4%), anorexia(61.5%), nausea(53.8%), general weakness(50.0%) and dizziness(50.0%) were the major symptoms among the cases. The admission rate among the cases was 24.1%(1 male, 6 females). In the stool cultures, Salmonella species group D was isolated from 6 persons of 85 examinees. It was identified as Salmonella enteritidis by serological diagnosis. The samples of underground water were assessed Enon-compatible for drinking in 10 wells(83.3%) of this rural area and it was suggested that it could have been contaminated from cattle feces. There were two wells in the party house, one of them was contaminated by bacterias including E. coli. The contaminated water was stored in a water tank located on the rooftop. This water was used for dish washing and cooking. Wd concluded that the cause of this epidemic was the underground water contaminated by Salmonella enteritidis from guman carriers or domestic animal carriers.