Food poisoning outbreak in a training establishment: A retrospective cohort study

Abstract

Background: An outbreak of food poisoning occurred among recruits in a training establishment. Investigation of outbreak was undertaken with active preventive interventions concurrently to arrest the current outbreak as well as to avoid such incidents in future. Materials and Methods: A retrospective cohort study was undertaken among all recruits, regardless of presence or absence of symptoms. The risk ratios (relative risks) and attributable risks were calculated for each food item of the suspected meal to assess the association between consumption of individual food items and subsequent illness. An environmental survey was undertaken to investigate into the course of food processing and storage facilities at trainees' galley (cookhouse) and other relevant eating establishments. Results: A total of 494 recruits reported with symptoms of gastroenteritis in a span of 3 days. Of those affected, only 9 were admitted and rest recovered with treatment on OPD basis. The overall attack rate was 22.9%. No deaths were reported. It was a classical point source, single exposure gastroenteritis outbreak. When food histories and sickness histories were analyzed, the attributable risk (24.17) and relative risk (5.11) were highest for the “Flavoured milk,” which was an outsourced item. The statistical findings were substantiated with environmental and epidemiological evidence. Conclusion: Epidemiological investigation incriminated dinner of the previous day as the meal responsible for the outbreak with flavored milk as the most attributable food item.