Abstract

OBJECTIVE On 4 March 2010, the Department of Epidemiological Surveillance and Intervention of the Hellenic Centre for Disease Control and Prevention was notified about an outbreak of gastroenteritis among high school pupils who had stayed at a hotel of the Prefecture of Central Macedonia from 11 to 15 February 2010, in the context of a school excursion. The aim of this study was to detect the possible source of the outbreak and to define the mode and the vehicle of disease transmission. METHOD A retrospective cohort study was conducted. Individuals who had participated in the school excursion were interviewed via a structured questionnaire, which covered demographic data and information about the disease and possible exposures. Epidata v3.1 was used for data entry and STATA v11.0 for data analysis. Relative risks (RR) and 95% corresponding confidence intervals (CI) were computed for all the risk factors tested. An association was considered statistically significant when the p value was <0.05. The presence of statistically significant independent associations was examined via multiple logistic regression using backward elimination techniques. Risk factors for which the univariate analysis showed a p value <0.05 and RR >3 were included in the multivariate analysis model. A culture was ordered for one stool sample taken from a student. The Health Directorate conducted an environmental inspection of the hotel's kitchen premises and the procedures followed during food preparation. 

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