Pijnacker R, et al. - In this work, a large multi-country outbreak of Salmonella enterica serotype Enteritidis in the EU and European Economic Area (EEA) was reported. Researchers defined a confirmed case as a laboratory-confirmed infection with the outbreak strains of S Enteritidis based on whole-genome sequencing (WGS), and a probable case as laboratory-confirmed infection with S Enteritidis with the multiple-locus variable-number tandem repeat analysis outbreak profile. Eight hundred thirty-eight confirmed and 371 probable cases were reported in 18 EU and EEA countries. As per the case-control study, cases more often ate in food establishments but were identified not to be linked to any specific food item. Performing recipe-based food trace-back investigations among cases who ate in food establishments, they recognized eggs from Poland as the vehicle of infection in October 2016. Two strains of S Enteritidis were identified in human cases that were subsequently identified in salmonella-positive eggs and primary production premises in Poland, confirming the source of the outbreak. The number of cases decreased following implementation of control measures, but these increased again in March 2017, and the increase continued into 2018. This indicates continuous entery of the outbreak strains in the food chain, although they identified changes in strain population dynamics and fewer cases indicating some effects of control measures. This outbreak thereby underscores the public health value of multi-country sharing of epidemiological, trace-back, and microbiological data. They suggest routine use of WGS in salmonella surveillance and outbreak response as promising to identify and stop outbreaks in the future.