Contributing Factors in a Successful Foodborne Outbreak Investigation: an Analysis of Data Collected by the Foodborne Diseases Active Surveillance Network (FoodNet), 2003-2010

Background. Foodborne disease is estimated to cause 48 million illnesses annually in the US resulting in 3000 deaths [1]. Although most infections occur as sporadic cases, outbreak surveillance offers valuable insight about the foods and pathogens responsible for illnesses [2]. A total of 1632 foodborne disease outbreaks were reported during 20112012 [3] and recent data indicates an overall decrease in the number of outbreaks reported each year [4]. Understanding which factors contribute to the successful identification of a food vehicle in a foodborne outbreak investigation is crucial for improving outbreak response [5-10]. The purpose of this study was to describe outbreak characteristics and to determine which may be associated with the success of a foodborne outbreak investigation (i.e. one in which a food vehicle has been reported). Methods. A foodborne disease outbreak was defined as the event in which two or more people acquired similar illnesses from consuming the same food or beverage.Outbreaks occurring in FoodNet sites during 2003 through 2010 were included in the analysis. Results. Data were available for 1441(87%) of the 1655 foodborne disease outbreaks documented in FoodNet Outbreak Supplement Forms from 2003 through 2010. A food vehicle was identified in 692 of the 1441 (48%) outbreaks. Six outbreak characteristics remained statistically significant in both univariate and multivariate analyses: environmental and/or food culture collection, FDA or state agriculture involvement, outbreak size, case-control studies, and number of fecal specimens tested for norovirus. Conclusions. Less than half of foodborne outbreaks examined here resulted in a food vehicle being identified. Having more robust resources available for outbreak detection and investigation may improve likelihood of a food vehicle being identified. CONTRIBUTING FACTORS IN A SUCCESSFUL FOODBORNE OUTBREAK INVESTIGATION: AN ANALYSIS OF DATA COLLECTED BY THE FOODBORNE DISEASES ACTIVE SURVEILLANCE NETWORK (FOODNET), 2003-2010