A recent study has demonstrated the benefits of interagency collaboration during foodborne illness outbreak investigations. The study was conducted by researchers from the U.S. Food and Drug Administration’s Center for Food Safety and Applied Nutrition (FDA’s CFSAN) and the U.S. Centers for Disease Control and Prevention (CDC).

The focus of the study was Sample-Initiated Retrospective Outbreak Investigations (SIROIs), which are initiated by the recovery of pathogenic microbial isolates from food product or environmental samples, followed by the identification of a cluster of genetically related clinical isolates, with subsequent epidemiologic and traceback investigations confirming a link between a suspect vehicle and illnesses. SIROIs, which are used by used by federal public health and regulatory partners in the U.S., are enabled by the increasing use of whole genome sequencing (WGS) for isolates of foodborne pathogens, as well as the ability to share and compare data on public platforms.

According to an analysis of two case studies, SIROIs allow for earlier hypothesis generation, followed by targeted collection of information about food exposures and the foods and manufacturer of interest, to confirm a link between the illnesses and their source. SIROIs often lead to earlier action that could reduce the breadth and burden of foodborne illness outbreaks, and include other benefits like insight into foodborne illness attribution, international collaboration, and opportunities for enhanced food safety efforts among industry. On the other hand, there exist challenges to SIROIs, such as resource intensiveness, variability of epidemiologic and traceback data, and an increasingly complex food supply chain.

The two case studies investigated were a 1) 2018 outbreak of illnesses caused by ice cream contaminated with Listeria monocytogenes, and 2) a 2018 outbreak of Salmonella Agbeni illnesses possibly linked to cake mix. These two outbreaks were chosen as they required the mobilization of a significant number of public health professionals and resources at the local, state, and federal level. Additionally, evidence produced during the SIROIs led to product recalls, facility inspections, sampling activities, and communications to warn the public about the recalled products.