The investigation of a food poisoning outbreak in A School, Muang district, Uthai Thani Province on June 2021

Abstract

On June 2, 2564, at 14:30, the Situation Awareness Team (SAT) of the Disease Control Office in Nakhon Sawan Province received a notification from the Public Health Office in Uthai Thani Province that there were more than 100 students from a school in Mueang District, Uthai Thani Province, who had symptoms of diarrhea, abdominal pain, and vomiting. The SAT team from the Disease Control Office in Nakhon Sawan Province, in collaboration with the Public Health Office in Uthai Thani Province, conducted a disease investigation to confirm the diagnosis, assess the epidemiological characteristics on an individual basis, and identify the risk factors and sources of the outbreak. They also proposed appropriate control and prevention measures. The study utilized a retrospective cohort study design, conducting individual interviews with suspected patients, including students and staff of the school, who experienced symptoms such as diarrhea, vomiting, abdominal pain, or neurological symptoms between May 31 and June 4, 2564. In addition to studying the environmental factors and conducting laboratory testing, the investigation found that out of the 379 individuals interviewed, there were 162 patients, resulting in a case rate of 42.74%. Among them, 159 were students, and 3 were teachers. The majority of the patients were female, accounting for 48.30%, while males accounted for 29.82%. The predominant symptoms observed were diarrhea (93.83%), followed by abdominal pain (76.54%), fatigue (47.53%), headache (44.44%), and vomiting (38.89%). The epidemiological analysis revealed that mango consumption was a significant risk factor, with an adjusted odds ratio of 2.29 (95% confidence interval 1.30-4.02, p-value 0.003). Laboratory testing identified the Bacillus cereus group from the hands of three food handlers, drinking water in the cafeteria, and water used for food preparation in the kitchen. Additionally, Escherichia coli, Staphylococcus aureus, and Bacillus cereus were found in samples of fresh milk-based "Chao Kuay" desserts. The outbreak of foodborne illness in a school in Uthai Thani Province appears to be a mixed-source outbreak, likely due to the contamination of food by Bacillus cereus during the food preparation process. Therefore, it is recommended to focus on food and water hygiene measures and ensure the cleanliness of water dispensers to prevent the recurrence of similar incidents.