Increased release of Stx2 compared with Stx1 might contribute to the high HUS risk that has been associated with Stx2-producing EHEC [18,19]: as EHEC are non-invasive and do not cross the intestinal epithelium and cause systemic infection, it is likely that HUS is caused by Stx released into the gut lumen which subsequently gets access to the bloodstream. Here, STX1A is linked to hemolytic-uremic syndrome.