Authorities in Denmark and Sweden are investigating the source of a Salmonella Braenderup outbreak affecting both nations.  Since mid-April in Sweden, 17 females and 5 male patients have been diagnosed.  In Denmark between late March and through April, 24th cases of Salmonella Braenderup were reported with a gender ratio of 17 females to 7 males.

The isolates from various patients have been sequenced and were all Type-22 with close similarity suggesting a common vehicle of infection.  The disproportionate gender ratio of 3:1 is uncommon for a foodborne infection unless the pathogen is associated with a specific food item favored by either gender.  The cases are widely distributed among regions in both Denmark and Sweden with an wide range of ages among patients.

Salmonella Braenderup was identified in an outbreak involving 35 cases in the U.S. in 2018.  In this outbreak, the vehicle of infection was presumed to be eggs derived from a specific complex holding two million hens.  The pathogen was isolated from the environment of the packing plant and from manure beneath cages in the complex that subsequently underwent depletion and decontamination.  Since restocking, upgrades to plant finishes, inclusion of an organic acid complex in feed and imposition of enhanced biosecurity and intensive testing, no additional cases have been diagnosed in the U.S.