STX1A and hemolytic-uremic syndrome: The much higher frequency of antibodies to Stx2 than to Stx1 in controls together with the observation of a high prevalence of Stx2/Stx2c-producing STEC in beef cattle [37], as well as in stools from post-enteric HUS cases in Argentina [8], [31], suggest that Stx2-producing strains are much more common than Stx1-producing ones.