Salmonella is associated with a large number of cases of foodborne infection resulting in diarrhea and, in some cases, more severe complications. Half of all Salmonella infections in the European Union are linked to pigs, and a new strain called ST34 is currently dominant in this livestock animal. ST34 has now spread in pig populations worldwide and is pandemic.  

The ST34 strain is a type of Salmonella Typhimurium, which accounts for a quarter of all Salmonella infections. New multidrug-resistant (MDR) strains of Typhimurium are known to have emerged repeatedly since surveillance records began over 60 years ago. In the UK, over half of all Typhimurium infections are now caused by the ST34 strain. Typhimurium has been increasing as a proportion of all Salmonella infection for more than a decade, largely due to the emergence of this new strain in pigs.