Foodborne illnesses are usually infectious or toxic caused by bacteria, viruses, parasites, or chemical substances entering the body through contaminated food. The current outbreak of foodborne diseases occurred in a girls' primary school in Riyadh City, Saudi Arabia, on December 21, 2023. The current outbreak investigation aimed to confirm the existence of the outbreak, identify the source of the outbreak, determine the causative agent or organism if possible, and recommend preventive measures to be applied to prevent similar outbreaks in the future. A retrospective cohort study was conducted to study the current outbreak. Cases were defined as any person who ate during an open day in the primary school for girls on December 21, 2023 and developed any or a combination of the following symptoms: diarrhea, vomiting, fever, or abdominal pain within 36 hours of food consumption. We collected information on demographics, symptoms, and food history using a semi-structured questionnaire. We reviewed available laboratory results for cases, retained food items, and conducted an active case search to identify more cases. The data obtained was analyzed using epi info and SPSS version 23. Risk ratios (RR) and 95% confidence intervals (CI) were calculated. 145 female cases among 259 ate during an open day in the primary school in Riyadh, which indicated an attack rate of 55.98%. Of 145 cases, The ages ranged between 6-40 years. Among cases, 97.93% had abdominal pain, 57.93% had nausea, 23.44% had vomiting, 18.62 developed diarrhea, and 4.82% had fever. The incubation period ranged from 45 minutes to 5.5 hours, with a mean of 2.5 hours. Among nine food items consumed, chicken burger (relative risk 1.64, 95% CI 1.35-2), cotton candy (relative risk 1.69, 95% CI 1.4-2.04), balilah (relative risk 1.44, 95% CI 1.06-1.93) and shawarma (relative risk 1.31, 95% CI 1.05-1.64) were significantly associated with illness. Laboratory investigation of food samples ( chicken burger, chips and grape leaves) and six rectal swabs were negative. There were no hospitalizations or deaths, and all cases were discharged. Based on symptoms, incubation period, epidemiological investigation, and laboratory results there might be some differential diagnosis, but we were unable to definitively identify the source of the outbreak. The current outbreak could be caused by chemicals or toxins in Chicken Burger, Shawarma, Balilah, and cotton candy. Cross-contamination may explain why so many food items were implicated. We recommend increased supervision and periodic examinations for food handlers and more education for food handlers about food safety.

Asma completed her Master’s degree in Field Epidemiology in 2024 from King Saud University, Saudi Arabia. She is currently serving as the Head of the Communicable Disease Department in a governorate in Oman. She has one published paper and two ongoing research projects that are currently in the process of publication.