On Saturday 26th of February 2011, 39 cases suffering from pain in the abdomen associated with severe diarrhea were reported from two private health care centers in Ha'il. The victims were a group of construction workers in the company responsible for construction of new Ha'il university buildings. On the next day the health and municipal authorities visited the site, and laboratory investigations were done. Field Epidemiology Training Program (FETP) team was asked to investigate the outbreak.
Methodology
A descriptive followed by case control studies was conducted. Self-administered questionnaire was used to extract relevant information from cases and controls. A case was defined as any person who had eaten from the company's restaurant on Friday 25th of February 2011 and had developed - within 12 hours - any gastrointestinal tract symptoms such as abdominal pain, diarrhea, vomiting, or fever. Any person who had eaten the same food at the same time and had not developed any gastrointestinal symptoms was considered as a control. Environmental investigation was done and laboratory investigations were obtained.
Results
A total of 76 persons (38 cases and 38 controls) filled the questionnaire. One case was excluded since they did not fulfill the case definition. All cases developed diarrhea and abdominal pain 38 (100%), but few developed vomiting and fever. A strong association between consuming green salad and the appearance of symptoms was revealed (Attack Rate = 72.09%; Odds Ratio = 9.60; 95% Confidence Interval = 3.30 - 27.92); laboratory results showed the presence of Staphylococcus aureus in the green salad and some other items as well as in the swabs obtained from food handlers. Environmental investigation showed below standard restaurant hygiene.
Conclusion
Improper food handling practices contributed to the development of this outbreak. The Green Salad was the implicated food item, and most likely staphylococcus aureus was the organism responsible for this outbreak.