Hemolytic uremic syndrome (HUS) is a disease that usually affects infants and children. The most common form of HUS is caused by consuming food or water contaminated with strains of Escherichia coli bacteria called enterohemorrhagicE coli. The first symptoms of infection include diarrhea, which may be bloody. Toxins released by the bacteria are thought to damage the intestines and then spread through the blood to the kidneys. Hemolytic uremic syndrome may develop within 1 week of the appearance of diarrhea and is considered the most common cause of sudden kidney failure in children. Atypical HUS is a less common form and is associated with improper function of the complement system, blood proteins involved in the natural immune response. This form of HUS is sometimes hereditary and recurrent. The March 14, 2012, issue of JAMA includes an article on enterohemorrhagic E coli .