A national news paper had a prominent news report on Tuesday 18/8/1424 H (14 October 2003 G) regarding an unusual incident of sudden onset of abdominal colic and vomiting among more than 35 students at a boys primary school at the National Guard residence compound in Dammam, Saudi Arabia, after eating food bought from the school canteen the day before. 26 students had been transported from the school to the emergency departments. One student needed gastric lavage and another needed hospitalization. The Field Epidemiology Training Program (FETP) decided to investigate this outbreak in order to identify cases and the implicated food, determine factor(s) associated with the occurrence of the outbreak, establish measures to control and contain the spread of the outbreak, and place recommendations to prevent similar outbreaks in future.
Methodology
a case-control study was carried to investigate this outbreak. A case was defined as any student from the school who had sudden symptoms of nausea, abdominal colic, vomiting or diarrhea, after eating or dinking food or drinks bought from the school canteen on Monday 17/8/1424 H. A control was selected randomly from the same class of each case. Data was collected by interviewing both cases and controls using a uniform pre-structured questionnaire. Data was entered and analyzed using SPSS version 10 soft ware for Windows.
Results
67 students met our case definition. Another 67 students were selected as controls. 33 (49.3 %) of the cases consulted the health services of the National Guard. The most common symptoms reported were abdominal colic (92.5%) followed by fever (34.3%), headache (34.3%), vomiting (31.3%), nausea (22.4%) and diarrhea (16.4%). Most of the cases were from the 6th grade (68.7%). The rest of the cases were distributed almost equally between other grades. The ages of cases ranged from 6-14 years (median 12 years) The Incubation Period ranged from 15 minutes - 8.5 hours (median min.). A high OR was found for eating za'atar fata'yer (OR =3.9, 95% CI = 1.9-8.0) and drinking bottled water (OR= 8.6, 95% CI= 1.9-39.5) bought from the school canteen. Other food items were not significant. Stratified analysis of exposure to za'atar fata'yer and getting disease in different grades showed a significant OR for students of the sixth grade only (OR = 6.2, 95% CI= 2.36-16.11). Further analysis of exposure to the bottled water failed to procure any real association. All the stool samples collected from the cases, the gastric lavage sample, and Za'atar fateera sample were negative for Food Borne Disease pathogens. All the swabs and samples obtained from the school canteen worker were negative. Some of the swabs of the bakery workers had grown staph. aureus and E. coli. Fata'yer samples collected from the bakery had also grown staph. aureus and E. coli. The school canteen and the canteen supplier warehouse environments were not suitable for storing food, and the bakery workers were not strict on wearing gloves and head covers.
Conclusion
The short incubation period of mostly upper gastrointestinal symptoms in this outbreak suggest food borne intoxication. Bacterial enterotoxins most likely staph. aureus were the causative agent of the outbreak. Za'atar fatayer served in the school canteen was the most probable implicated food item. Contamination from food handlers and poor storage and transportation method are the most likely contributing factors. We recommended composition of an internal inspection team in the school to supervise the canteen and the supplier using a special form to be sent weekly to the preventive office; correction of the school canteen environment; emphasis on the use of safe raw materials from safe sources; application of HACCP (Hazard Analysis Critical Control Point Evaluation) in the inspection of food safety in the food industry rather than depending on the final product analysis.