A food poisoning outbreak in a medical seminar at Hotel A, Dindaeng district, Bangkok during 15-19 July 2015

Abstract

Introduction: Background: On 20 July 2015, a notification of food poisoning cluster among attendees of medical seminar at hotel A, Dindeang district, Bangkok. The surveillance and Rapid Response Teams from Public Health Center 22 Wat Pakbor and Public Health Center 52 Samsennok together with Office of Disease Prevention and Control 13, Bangkok and Food Sanitation Division, Health Department, Bangkok Metropolitan Administration conducted an outbreak investigation and control the spread during July 20-August 2, 2015.
Methods: Descriptive study was done by interviewing cases and food handlers in the hotel. Active case finding was done among the seminar attendees by telephone interview. A case was defined as a seminar attendee who had at least one of the following symptoms: watery stool, mucus stool, loose stool, abdominal pain, neausea/vomiting and dyspepsia during 15–19 July 2015. Stool samples were collected and sent for enteropathogenic bacteria culture and PCR test for Norovirus and Rotavirus. Food sanitation in the hotel kitchen was inspected and rectal and hand swabs among food handlers were collected for bacteria culture.
Results: Totally, twenty five cases met a case definition in active case finding. Male was seventeen cases (68.00%). The median of age was thirty-eight years (25-66 years). Epidemic curve suggested a point common source outbreak. The most common clinical presentations included abdominal pain, vomiting and loose stool diarrhea respectively. Two cases were positive Norovirus PCR in fresh stool and another one was positive for Salmonella group C. Ten rectal swabs for bacterial culture were all negative. One hotel chef’s rectal swab was positive for Salmonella spp. The seven samples of food samples and water were negative for enteropathogenic bacteria. Water and ice were also negative for Norovirus and enteropathogenic bacteria. But crunched ice was positive for Stapylococcus aureus. Fresh oyster was significantly associated with illness (adjusted OR=5.49, 95% CI 1.08-27.98), p-value=0.04.
Conclusions and recommendation: The causative agent of this food poisoning outbreak was likely Norovirus which was compatible with prominent clinical presentation of upper gastrointestinal tract and consumption of fresh oyster. The food sanitation needed to be improved as evidence by bacterial contamination in the kitchen and food handlers. Frequent hand washing, disinfecting contaminated surfaces and washing fabrics by hot water were recommended to minimize the likelihood of disease spreading.