Shiga toxin (Stx) production, especially Stx1a, Stx2a, Stx2c, and Stx2d, has been implicated in causing severe disease and HUS, and STEC carrying Stx2b are mainly associated with diarrheal disease (Friedrich et al., 2002; Jelacic et al., 2003; Bielaszewska et al., 2006). The gene discussed is STX1A; the disease is diarrheal disease.