ADAMTS13 and thrombotic thrombocytopenic purpura: The most widely described association between an infectious agent and TTP is that of Shiga toxin released from E. coli, predominantly types O157:H7 [4, 5]. E. coli bacterial toxins are considered to be a main cause of TTP with no renal abnormalities in hemorrhagic colitis patients [5]. E. coli toxins are also believed to decrease ADAMTS13 activity, thereby resulting in abnormally large von Willebrand factor multimers in plasma which in turn cause the disseminated platelet thrombi characteristic of TTP [6, 7].