Search

OBJECTIVES: In July 2019, there were multiple reports on patients with hepatitis A among the visitors of a restaurant in Busan. The current study presents the results of an epidemiological investigation and outlines the supplementary measures that would help with hepatitis A control. METHODS: A cohort study was conducted for all 2,865 customers who visited restaurant A from June to July. Using a standardized questionnaire, participants reported the presence of hepatitis A symptoms and whether they had consumed any of 19 food items. As for participants who had visited public health centers, their specimens were collected. RESULTS: From the study cohort, 155 participants (5.4%) had confirmed hepatitis A. The epidemic curve was unimodal, and the median number of days from the restaurant visit to symptom onset was 31 days. A genotype analysis indicated that 89 of 90 tested patients had hepatitis A virus (HAV) genotype 1A. The results of a multivariate logistic regression analysis indicated that the ingestion of salted clams increased the risk of hepatitis A by 68.12 times (95% confidence interval [CI], 9.22 to 510.87). In an unopened package of salted clams found and secured through traceback investigation, HAV genotype 1A was detected. CONCLUSIONS: To prevent people from ingesting uncooked clams, there needs to be more efforts to publicize the dangers of uncooked clams; the food sampling test standards for salted clams should also be expanded. Furthermore, a laboratory surveillance system based on molecular genetics should be established to detect outbreaks earlier. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to reveal the epidemiologic characteristics of the outbreak of gastroenteritis caused by Salmonella enterica serovar Thompson in Busan Metropolitan City and to identify points for improvement to prevent of food-borne disease outbreak.Methods: This was a case-control study. The control group comprised asymptomatic students in the same classes of the cases. The presence or absence of symptoms, ingestion of each food provided by school meal service, and commonly ingested foods in addition to those foods in meal service were investigated. Moreover, specimens collected from rectal swab, preserved foods, and environmental surface were tested.Results: Of the 6,092 subjects, 1,111 (1,083 students, 22 school personnel, and 6 foodservice employees) were included in the case group; this corresponded to an 18.4% attack rate. Symptoms included diarrhea (n=1,051, 94.6%), abdominal pain (n=931, 83.8%), febrile sensation (n=502, 45.2%), and vomiting (n=275, 24.8%). The epidemic curves of each 10 schools were unimodal. Investigation of food intake showed a significantly high odds ratio for chocolate cake in 5 out of the 10 schools. Laboratory test detected Salmonella enterica serovar Thompson both in rectal swab specimens of 9 schools and in collected preserved chocolate cakes of 9 schools. Pulsed-field gel electrophoresis test result showed that Salmonella enterica seorvar Thompson isolated from human and foods were the same.Conclusions: The source of infection for the Salmonella enterica serovar Thompson outbreak in the 10 schools of Busan Metropolitan City is chocolate cake. Traceback investigation for origin of contaminated food in food-borne disease outbreak and safety control during food production should be more enhanced. [ABSTRACT FROM AUTHOR]