Title : Food poisoning outbreak caused by bacillus cereus at a secondary school in Uganda july 2023
Abstract:
Introduction: Bacillus cereus is a foodborne bacterial pathogen. Infection causes abdominal pain and diarrhoea; incubation is typically 4-16 hours. On July 20, 2023, Uganda Ministry of Health was notified of a suspected food poisoning outbreak at Nakanyonyi Secondary School in Mukono District. We investigated the incident and recommended control measures.
Methods: We defined a case as sudden onset of abdominal pain, diarrhoea or vomiting from July 19–20, 2023 in a student or staff member at Nakanyonyi Senior Secondary School. We found cases by reviewing school and health facility records and created a line list. We subjected cases to a questionnaire and conducted descriptive epidemiology and environmental assessments. We tested our hypothesis in a cohort of all boarding students.
Findings: Among 267 cases (all students), 13% were commuters and 87% were boarders. The most common symptoms included abdominal pain (100%), diarrhoea (92%), and vomiting (16%). The epidemic curve indicated a point-source outbreak with onsets occurring 6-36 hours after eating school lunch or dinner. Posho and beans from the same bags were consumed on preceding days with no illness reported, suggesting that the food was contaminated during preparation on that day. Nearly all 299 cohort members ate the food for lunch and/or dinner on July 19; 229 (78%) of 295 students who ate the school lunch and/or dinner and none (0%) of the 4 students who ate neither meal became ill (RR=7.8; 95%CI 0.56-108). Attack rates were similar for those who ate only lunch (80%), only dinner (77%), or both (78%). Bacillus cereus was isolated from leftover samples of the cooked food.
Conclusion: This was a point-source outbreak likely caused by Bacillus cereus in food cooked at school; the mechanism of contamination was unknown. Proper food handling, preparation, and storage were emphasized to prevent repeat occurrences.
Audience Take Away:
- The audience will gain some insight on the intricacies involved in investigating and managing outbreaks of food borne illnesses including the rigorous process of tracing the source of contamination, identifying affected individuals, and implementing control measures. They will also appreciate the complexities involved in public health emergency responses.
