title: Applying standard epidemiological methods for investigating foodborne disease outbreak in resource-poor settings: lessons from Vietnam.
abstract: An outbreak of gastroenteritis occurred among workers of company X after eating lunch prepared by a catering service. Of 430 workers attending the meal, 56 were hospitalized with abdominal pain, diarrhea, vomiting, and nausea, according to the initial report. We conducted an investigation to identify the extent, vehicle, and source of the outbreak. In our case-control study, a case was a worker who attended the meal and who was hospitalized with acute gastroenteritis; controls were randomly selected from non-ill workers. Cases and controls were interviewed using a standard questionnaire. We used logistic regression to calculate adjusted odds ratios for the consumption of food items. Catering service facilities and food handlers working for the service were inspected. Food samples from the catering service were tested at reference laboratories. Of hospitalized cases, 54 fulfilled the case definition, but no stool specimens were collected for laboratory testing. Of four food items served during lunch, only "squash and pork soup" was significantly associated with gastroenteritis, with an adjusted odds ratio of 9.5 (95 % CI 3.2, 27.7). The caterer did not separate cooked from raw foods but used the same counter for both. Cooked foods were kept at room temperature for about 4 h before serving. Four of 14 food handlers were not trained on basic food safety principles and did not have health certificates. Although no microbiological confirmation was obtained, our epidemiological investigation suggested that squash and pork soup caused the outbreak. Hospitals should be instructed to obtain stool specimens from patients with gastroenteritis. Food catering services should be educated in basic food safety measures.
authors.affiliation: Institute of Hygiene and Public Health, 159 Hung Phu Street, District 8, 70000 Ho Chi Minh City, Vietnam. vo.huuthuan@yahoo.com.
authors.forename: Thuan Huu
authors.initials: TH
authors.lastname: Vo
authors.affiliation: Food Safety Agency of Binh Duong, 211 Yersine, Thu Dau Mot City, 72000 Binh Duong Province, Vietnam.
authors.forename: Dat Van
authors.initials: DV
authors.lastname: Nguyen
authors.affiliation: Food Safety Agency of Binh Duong, 211 Yersine, Thu Dau Mot City, 72000 Binh Duong Province, Vietnam.
authors.forename: Loan Thi Kim
authors.initials: LT
authors.lastname: Le
authors.affiliation: Vietnam Field Epidemiology Training Program, 01 Ton That Tung, Dong Da District, 10000 Hanoi, Vietnam.
authors.forename: Lan Trong
authors.initials: LT
authors.lastname: Phan
authors.affiliation: School of Health Sciences, University of Tampere, FI-33014 Tampere, Finland.
authors.forename: J Pekka
authors.initials: JP
authors.lastname: Nuorti
authors.affiliation: Vietnam Field Epidemiology Training Program, 01 Ton That Tung, Dong Da District, 10000 Hanoi, Vietnam.
authors.forename: Nguyen Nhu
authors.initials: NN
authors.lastname: Tran Minh
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D016022:Case-Control Studies; D004196:Disease Outbreaks; D005260:Female; D005506:Food Contamination / Q000032:analysis*; D005511:Food Handling; D005516:Food Microbiology; D059022:Food Safety; D005517:Foodborne Diseases / Q000453:epidemiology* / Q000382:microbiology; D005759:Gastroenteritis / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D008297:Male; D008460:Meat / Q000382:microbiology; D013552:Swine; D014744:Vietnam / Q000453:epidemiology; D055815:Young Adult