Infectious Diseases 2019

Infectious Diseases 2019

An international outbreak of S. Enteritidis linked to eggs from Poland

Lancet Infect Dis - 2019 29 May, 2019

18 EU and EEA countries identified 1209 S. Enteritidis outbreak cases between May 1, 2015, and Oct 31, 2018, of which 838 were confirmed and 371 were probable. 509 (42%) cases were reported in 2016, after which the number of cases steadily increased. The case-control study results showed that cases more often ate in food establishments than did controls, but no specific food item was identified. Recipe-based food trace-back investigations among cases who ate in food establishments identified eggs from Poland as the vehicle of infection in October, 2016. Phylogenetic analysis identified two strains of S Enteritidis in human cases that were subsequently identified in salmonella-positive eggs and primary production premises in Poland, confirming the source of the outbreak. The eggs originated from Polish farms with a Salmonella-negative status. 
Following the withdrawal of the concerned eggs in Europe and the implementation of control measures in Poland, a sharp decrease in the number of cases was observed. However, in March, 2017, the number of reported cases increased again, with peaks in May and September. The increase continued in 2018, with a similar temporal pattern. Since 2018, routine sampling of laying hens at the farms have been intensified, but the source of the re-emergence remains unknown.