Introduction
On 15 November 2020, the General Health Directorate reported that an unexpected number of gastrointestinal illnesses had presented to the security forces hospital in Dammam. The patients were all students at a security campus in Abqaiq with a history of eating dinner at the same security campus. Our aims were to confirm the existence of the outbreak, define the cases, identify the source of the outbreak, determine the causative agent or organism, if possible, and its mode of transmission, and to recommend measures to be applied in order to prevent similar outbreaks in the future.
Methodology
1:2 ratio case-control study was conducted for the security campus students where a gastrointestinal illness had occurred among the students. All cases met the case definition (persons who resided in the security facility campus and ate any of the meals on 15 November 2020, and during 2-10 hours had any of these symptoms (abdominal pain, nausea or vomiting, diarrhea) .The controls were persons who ate the same food in the security campus and did not report any symptoms. Data was collected from the study group on demographics, symptoms and food history by using a pre-structured food-poisoning questionnaire. Environmental inspection supported the investigation in addition to the laboratory results for cases, food handlers, food items and the environment.
Results
Out of 800 students who had all the meals on the day of the incident, 106 students experienced symptoms of illness as follows: vomiting 90%, nausea 89%, diarrhea 73% and abdominal pain 69%. Laboratory analysis (throat swabs) affirmed the presence of Staphylococcus aureus bacteria. Analytic investigation showed that this illness was strongly associated with consumption of the salad with (OR= 34.50, P-value =0.00, 95%CI = 17.54-67.92).
Conclusion
This investigation revealed that the salad was the causative food item, and this outbreak was most likely caused by Staphylococcus aureus bacteria. This conclusion was based on symptoms, incubation period, the epidemiological investigation, and laboratory results. It has been revealed that negligence in the maintenance of the cooking or storage appliances by the food handlers, in addition to the low quality of sanitation of the raw food, induced the growth of a harmful Staphylococcus aureus and its toxins, which led to the outbreak. Periodic examination of the food handlers, and regular maintenance of the kitchen utilities and food reserving trollies, are recommended.