Outbreak Investigation of Food Poisoning in a School, Bangrak District, Bangkok, Thailand, May 2015

Abstract

Background: On May 27, 2015 at 03:40 p.m. the Public Health Center 23 Sipraya was informed by the nurse at allboy school that there were 42 patients infecting with several symptoms of watery diarrhea showing nausea, vomiting and abdominal pain. The SRRT of Public Health Center 23 Sipraya started the investigation and had controlled the outbreak during May 28-29, 2015.
Methods: The investigation was aimed to confirm preliminary diagnosis and disease outbreak, characterization of the disease and the spread of the disease, in addition to causes and factors contributing to the outbreak, with the goals to control and prevent the outbreak of disease. The descriptive and case-control study were conducted.
Results: Total number of patients were 47 cases, 45 of them were grade 1-6 students, 2 were teachers, only one case was a female. The median of age for the patients showed 6 years old with a distribution from a minimum of 5 years old and to a maximum of 50 years, who was a teacher. Most class specific attack rate were grade 1 students (6.53%), next were grade 4 students (2.60%). Onset of illness occurred at a mean of 3.7 hours after eating (range: 2-10 hours). The patients experienced the symptoms of diarrhea (100.00%), abdominal pain (85.00%), nausea (4.25%) and vomiting (4.25%), no patients were hospitalized (as outpatients). The result of the case-control study revealed that the illness was strongly associated with eating Chinese steamed wonton (OR = 18.90, 95% confidence interval 5.11- 69.78, p-value < 0.0001). The samples of stool (rectal swab culture) obtained from the ill persons were positive for Staphylococcal aureus; 3 in 4 cases of ill persons and 24 persons of the food handlers without diarrhea were tested positive for Staphylococcus aureus 4 cases, Salmonella gr. E 1 case and Salmonella gr. B 1 case. The hand swabs in 24 persons of the food handlers without diarrhea were deemed positive for Coliform bacteria 2 cases. The samples of tap water and drinking water from water dispenser in front of classroom and canteen were not founded containing bacterial pathogen.
Conclusions: The prevention and control measures were recommended by avoiding to keep food at the room temperature for a long time before serving (the students in the afternoon), health education on food sanitation, personal hygiene and ways to combat diarrhea including collaboration of Public Health Officers, Pathum Thani province for controlling the standard of restaurants and food vendors. We conducted a close surveillance for another two days, there were no patients found.