In the periodbetween 18 and 20 April 2011 a total of 47 patients attended to Hail General Hospital in Hail City complaining of gastrointestinal symptoms after eating at a restaurant. We started an investigation to identify the food item responsible for the outbreak and determine the source of infection.
Methodology
A case control study was conducted. A case was defined as any person who ate from the restaurant between 18/4/2011 to 20/4/2011 and developed gastrointestinal illness within two days of food consumption. A control was defined as any person who ate from the same restaurant during the same period and did not develop gastrointestinal illness during the period of the outbreak. We took a sample of 47 cases and 47 controls and asked them about food consumption and symptoms and admission history.
Results
Out of all the cases, 47(100%) developed gastroenteritis manifested by diarrhea, fever, abdominal pain, nausea and vomiting. Those who had eaten chicken shawarma 87.7%became sick (OR=73.5, 95% C.I =19.3-279.3). Salmonella enteritidis group D was isolated from 47(100%) of cases who gave stool or rectal swabs specimens. All cultures that were taken from the restaurant food items showed no growth for any pathogen. For the food handler cultures, all stool samples were positive for R. Ornithionlyt except two were negative but all their under nail samples were positive for enterobacter. Mayonnaise was made in the restaurant by blending egg yolks, oil and garlic by restaurant workers.
Conclusion
This common source outbreak of salmonella resulted from restaurant prepared mayonnaise served with the shawarma between 18/4/2011 to 20/4/2011. The serotype enteritidis suggest that the organism originated from the egg products. Heavy contamination probably resulted from temperature abuse of mayonnaise and eggs causing high infectivity.