Public Health Authorities in the Netherlands have investigated an ongoing outbreak of Salmonella Enteritidis (SE) since September 2023.  To date there have been 171 laboratory-confirmed cases with the presumption that the real incidence exceeds this figure by a factor of 10 to 20.

Whole genome sequencing on SE isolates from patients demonstrated two separate clusters, one associated with floor housed flocks and the other from hens with outside access.  Salmonella Enteritidis isolated from 14 laying farms could be corelated with isolates obtained from patients.

Investigation disclosed a problem of recycling eggshell that was improperly heat treated before inclusion into feed as a mineral supplement thereby perpetuating infection.

Salmonella infection should be identified proactively in flocks and not in patients.  A mandatory monitoring system such as the FDA Final Rule or state EQAPs or those imposed by individual companies are required.  It is difficult to understand how in an industrialized nation such as the Netherlands a prolonged SE outbreak could persist without appropriate diagnostic and corrective action to protect consumers. It is hoped that investigators involved will publish on the epidemiology of the extended outbreak.