A Food Poisoning Outbreak in the Policemen at the Royal Thai Government House, Bangkok, March 2011

Abstract

Background: On 16 March 2011, a cluster of food poisoning among policemen in charged for the Crowd Control Subdivision (CCS), at Royal Thai Government House (RTGH) was notified to Bureau of Epidemiology. Outbreak investigation was initiated on the same day to verify diagnosis, describe magnitude, identify source and risk factors of infection, and recommend prevention and control measures.
Methods: We conducted a retrospective cohort study among all policemen of CCS at RTGH. A suspected case was a policeman of CCS in the affected shift who had diarrhea with either abdominal pain, nausea, vomiting, or fever during 16-18 March 2011. Environmental survey of the cooking areas as well as rectal swab of cases and food handlers, and food cultures were assessed.
Results: Of the 52.87% policemen available (92/174), 51 were suspected cases (attack rate=55.43%). Median age of cases was 28 years old (range=24-44). The epidemic curve showed common source outbreak pattern with median incubation period of 13.15 hours (range=3.00-24.00). Common symptoms included diarrhea and abdominal pain (100%), nausea (35.30%) and fever (17.60%), no hospitalization. Fried-rice with crab was the only suspected food (RR=infinity, p-value <0.001). Rectal swab of five from seven patients and one cook helper were positive for Vibrio parahaemolyticus. Leftover crab used for fried-rice preparation was positive for Aeromonas caviae and E. coli. All raw food materials were put in the same ice bucket. Ready to eat crab was reheated and put above the fried-rice 2.5 hours before eating. Cook and food handlers used bare hand while cooking.
Conclusions: The outbreak was likely caused by Vibrio parahaemolyticus. Fried-rice with crab and food handler with unhygienic food preparation was the suspected source. Improved personal hygiene and food sanitation was recommended.