Usually a mild gastrointestinal illness that occurs 3 to 5 days after eating contaminated food. Severe complications, however, can arise. Hemorrhagic colitis is distinguished by the sudden onset of severe abdominal cramps, little or no fever, and diarrhea that may become grossly bloody. Although less than 5 percent of E. coli O157 disease cases develop hemolytic uremic syndrome (HUS), it is a severe, life-threatening illness. HUS is a disease characterized by red blood-cell destruction, kidney failure, and neurological complications, such as seizures and strokes. Most HUS cases are children under 5 years old, although the feeble elderly may also be at risk.