STX2 and infection: Some of the subtypes of stx2 have been significantly associated with the most severe infection (Friedrich et al., 2002), while some other subtypes of both stx1 and stx2 seemed to be primarily associated with a milder course of the disease or confined to animal hosts (Friedrich et al., 2002; Bielaszewska et al., 2006; Persson et al., 2007; Scheutz et al., 2012).