This inflammatory reaction is caused by toxins secreted by the bacteria, and is believed to be the cause of hemorrhagic colitis. Hemorrhagic colitis is characterized by the sudden onset of abdominal pain and severe cramps, followed within 24 hours by diarrhea. As the disease progresses, the diarrhea becomes watery and then may become grossly bloody - bloody to naked eye.
Vomiting can also occur, but there is usually no fever.
An incubation period of less than 24 hours would be unusual, however. In most infected individuals, the intestinal illness lasts about a week and resolves without any long term problems. Antibiotics do not improve the illness, and some medical researchers believe that these medications can increase the risk of complications. Therefore, apart from good supportive care, such as close attention to hydration and nutrition, there is no specific therapy. Most individuals recover within two weeks.