On 17th Nov 2010, an outbreak of acute gastroenteritis occurred among labourers at the Rass Laffan Industrial City. The aim of this study was to identify the agent and the source of the outbreak in order to stop it, develop control measures and prevent future outbreaks. A case-control study was conducted to study this outbreak. A total of 85 cases were randomly selected as well as 85 controls. Both groups completed a structured questionnaire. In addition, stool culture from patients and food handlers as well as food samples were investigated to determine the pathogen and the possible source of infection.
About 300 labourers developed the disease; attack rate is 28.5%. Diarrhoea and abdominal cramps were the most common symptoms. The median incubation period was 15 hours. Cases were more likely than controls to have eaten macaroni salad 97.6% and 27.3% respectively with OR 109.3 (CI: 25-484). Stool culture of 6 patients and 3 food handlers were positive for Salmonella group D and none of the food item showed microbial growth. The findings of this study indicate that the causative agent of this outbreak is Salmonella group D and the possible source of infection is macaroni salad, which was mixed with raw eggs.