Epidemiological Investigation of an Outbreak of Salmonellosis in Gyeongju, Korea

OBJECTIVES A salmonellosis outbreak occurred within a community of Gyeongju residents who ingested catered food from a wedding in June 2009. We aimed to epidemiologically investigate the probable vehicle of the infection. METHODS We conducted a retrospective cohort study on 34 local residents who ingested the wedding food. RESULTS Among the 34 residents, 31 (91.2%) reported symptoms of infection after eating the food. Among all of the wedding foods, pan-fried foods were highly associated with the diarrheal attack rate. On bacteriological examination, Salmonella species were detected in the pan-fried foods among the leftover foods and in 17 of the 31 stool specimens from the cases. There were five different types of pan-fried foods, but the onset of symptoms was independent of the ingredients used. We found that the pan-fried food was prepared at a food store in Seoul and that eggs were a common ingredient. CONCLUSIONS The major cause of the salmonellosis in this population was presumed to be the pan-fried food prepared with contaminated eggs. These food items might have been partially undercooked because of their irregular shape, which allowed the Salmonella species to survive and multiply before ingestion.