Margo Chase-Topping, Timothy J. Dallman, Lesley Allison , Nadejda Lupolova, Louise Matthews, Sonia Mitchell, Christopher J. Banks, Jamie Prentice, Helen Brown, Sue Tongue, Madeleine Henry, Judith Evans, George Gunn, Deborah Hoyle, Tom N. McNeilly, Stephen Fitzgerald, Alison Smith-Palmer, Sharif Shaaban, Anne Holmes, Mary Hanson, Mark Woolhouse, Xavier Didelot, Claire Jenkins and David L. Gall

For the last two decades, the human infection frequency of Escherichia coli O157 (O157) in Scotland has been 2.5-fold higher than in England and Wales. Results from national cattle surveys conducted in Scotland and England and Wales in 2014/2015 were combined with data on reported human clinical cases from the same time frame to determine if strain differences in national populations of O157 in cattle could be associated with higher human infection rates in Scotland. There was evidence of limited cattle strain migration between nations and clinical isolates from one nation were more similar to cattle isolates from the same nation, with sub-lineage Ic (mainly PT21/28) exhibiting clear national association and evidence of local transmission in Scotland. While we propose the higher rate of O157 clinical cases in Scotland is a consequence of the nationally higher level of Stx2a+O157 strains in Scottish cattle, we discuss the multiple additional factors that may also contribute to the different infection rates between these nations.

Microbial Genomics. September 2023