Researchers have discovered a new strain of salmonella in pigs, known as ST34, has spread with the aid of a bacterial virus. The Quadram Institute stated that this new strain of salmonella is dominant in pigs and has spread on a global scale.
The ST34 strain is a type of Salmonella called Typhimirium which accounts for a quarter of all Salmonella infections and over half in the UK. Typhimirium has increased as a proportion of all Salmonella infections for more than a decade mainly due to the emergence of this new strain.
Unlike Enteritidis, a related Salmonella, that has been largely controlled in layer hen flocks in UK, there has been little success in managing Typhimirium.
Public Health England (PHE) data has been used to analyse the genome sequence from human infections and indicated that a bacterial virus known as mTmV infected ST34 on multiple occasions from around 2002. By analysing the population structure of ST34 it was evident that Salmonella harbouring the mTmV virus in its genetic material became numerous over time and gained an advantage over the salmonella that lacked the virus. It also carried a gene called sopE encoding a toxin known to help Samonella to infect animal hosts causing diarrhoea and passed on to new hosts via food and feed.
It is hoped that the research will assist with understanding how and why new strains of Salmonella emerge in livestock and that strategies can be developed to reduce its occurrence.
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