Generally, STEC strains only expressing stx1 are associated with mild disease or asymptomatic carriage, while strains expressing both stx1 and stx2 are associated with greater pathogenicity, and strains expressing stx2 alone are recognized as ‘high risk’ due to their association with severe disease outcomes such as hemolytic uremic syndrome (HUS) and bloody diarrhea [2,3]. This evidence concerns the gene STX2 and hemolytic-uremic syndrome.