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Foodborne outbreak in Ahad Rafidah, Saudi Arabia, February 2009.


On Friday 27 February 2009 at 5.30 pm several cases of gastroenteritis arrived at the emergency department of Ahad Rafidah Hospital. They were complaining of diarrhea, abdominal pain and fever. Interviews revealed that all people who were sick belong to one extended family who attended reception dinner at the home of one of the members on Wednesday 25 February at 9.30pm. We started an investigation to identify the food item responsible for the outbreak and determine the cause of infection.


A retrospective cohort study was conducted. Person to person interviews with all family members, who attended the dinner in Wednesday 25 February at 9.30 pm, was done. Case definition included any one of the guests who developed any of the following symptoms: diarrhea, nausea, vomiting, abdominal pain, or fever, after eating dinner on Wednesday 25 February at 9.30 pm.


Out of the 35 guests 27 matched the case definition with attack rate of 77.1%. Gastroenteritis was most commonly manifested by abdominal pain (100%) and diarrhea (92%). The average incubation period of the disease was 50 hours. Meat and rice were significantly associated with the illness, with RR= 9, (95% CI=1.42-57.12), RR= 3.7, (95% CI= 1.11-12.36) respectively. Out of the 24 stool samples collected from cases 5(20.8%) positive for salmonella, 4 (16. 4%) positive for Amoeba and 4 (16. 4%) positive for both.


Dependent on the incubation period, clinical pictures and stool cultures; salmonella was considered the causative agent of this foodborne outbreak in presence of co infection by entamoeba histolytica. Rice and meat served in the dinner were the incriminated food items.