By Tuesday 21/7/1430H (14/7/2009) a total of 55 patients attended to hospital and primary health care center in Khaiber city complaining of gastrointestinal symptoms after eating from one restaurant. We started an investigation to identify the food item responsible for the outbreak and determine the source of infection.
Methodology
We conduct a case control study. A case was defined as any person who ate from the restaurant between 13/7/2009 to 14/7/2009 before 11 AM (the day and time that the authorities closed the restaurant) and developed diarrhea illness within three days of food consumption. A control was defined as any person who ate from the same restaurant at the same period and did not develop diarrhea illness during the period of the outbreak. We took a sample of 50 cases and 50 controls and asked them about food consumption and symptoms and admission history.
Results
All cases, 50(100%) developed gastroenteritis manifested by diarrhea, 47(94%) fever, 31 (62%) abdominal pain, 6(12%) nausea, 44(88%) vomiting. Mayonnaise salad had the highest odd ratio (OR=18.2) (95% C.I = 6.70 -49.55), followed by mutabal as second highest association (OR=16.62) (95% C.I = 6.13 - 45.03), other food items showed no association. The samples that were taken from the restaurant food handlers showed growth of staphylococcus aureus in throat swabs of 5 of them, two of these five workers showed the same organism in the nail swab, The samples that were taken from the restaurant food items showed growth of salmonella enteritidis group D1 in mayonnaise salad and mutabal, in addition the same serotype of salmonella was isolated from 6 patients. Mayonnaise salad was locally made in the restaurant and the eggs were one of its ingredients.
Conclusion
On the basis of this investigation, it is obvious that Salmonella entiritidis was the cause of the outbreak. Mayonnaise salad and/or Mutabal were the most probable immediate source of infection. Reservoir could be either raw eggs used in mayonnaise and reached mutabal through cross contamination; or the food handlers themselves contaminating both foods.