An outbreak investigation of food poisoning in Buddhist ceremony, Mueang District, Yasothon Province, Thailand, 2018

Abstract

Background: On 28th May 2018, Situation Awareness Team, Department of Disease Control (DDC) detected news reporting a hundred of patients presented with vomiting and diarrhea after attended Buddhist ceremony. Most of patients were students from seven schools in Yasothon Province. DDC and local public health team conducted investigation to confirm diagnosis, determine source of outbreak, and implement prevention and control measures.
Methods: Active case finding was conducted among students, teachers, officers in the affected schools and the villagers who attending the event including their relatives who shared the lunchbox. We defined the case as an event participant or their relative who had nausea, diarrhea or abdominal pain. Descriptive study was performed through medical record review during 28-29 May 2018, case interview about symptoms and meal with semistructure questionnaire. Retrospective cohort study was conducted to determine source of outbreak. We interviewed the food handlers to understand cooking processes and surveyed the cooking area. Specimens, including vomitus and rectal swab of patients, fingertips and nasal swab of food- handlers, and suspected food and water, were collected to identify the pathogens.
Results: Of 480 attendants joined this event, overall attack rate was 67.5% ( 324/ 480) . Major symptoms were vomiting ( 84.9% ) , abdominal pain ( 77.5% ) and diarrhea ( 62.3% ) with two hours mean incubation period. Hainanese rice chicken lunchboxes cooked by an unlicensed food shop were provided in this event. Consumption of lunchbox was strongly associated with the illness ( exact OR 53.9, 95% CI 8.9-inf.) . Laboratory testing of food samples revealed S. aureus with enterotoxin- A gene and B. cereus which was consistent with samples from patients’ vomitus and rectal swab. Moreover S. aureus with same toxin gene was isolated from cook’s nasal swab.
Discussion: This is a food poisoning outbreak caused by enterotoxin from S. aureus and B. cereus correlated with clinical symptoms and isolated organisms. This shop was temporary shutdown and event organizers were obliged to adopt only licensed food providers. Furthermore, event organizer should establish policy for appropriate selection of food supplier and menu.