Food Poisoning Outbreak in a Military Establishment

BackgroundAn outbreak of food poisoning involving 121 persons of a military establishment was investigated.MethodsOn investigation, a total of 94 persons became ill, with an attack rate of 77.7%. The symptoms included nausea, vomiting, abdominal pain, diarrhoea, weakness and fever. The mean incubation period was 2.3 hours while the median was 1.7 hours. Retrospective cohort study incriminated raita as the food item responsible for the outbreak, with a risk ratio of 21.35. Left over food was not available for laboratory analysis. There were no deaths and all affected persons recovered within 24 hours.ResultCoagulase positive staphylococci were cultured from the vomitus and stool samples of cases. Nasal and fingernail swabs collected from food handlers also showed staphylococcal growth. The most likely cause of contamination of raita with the enterotoxin could be the staphylococci which had colonised the bodies of food handlers.ConclusionThe aggravating factor was the storage of raita at room temperature before its consumption, which provided ideal conditions for enterotoxin formation.