Hemorrhagic colitis is a type of gastroenteritis in which certain strains of the bacterium Escherichia coli (E. coli) infect the large intestine and produce a toxin (Shiga toxin) that causes bloody diarrhea and other serious complications.
Hemorrhagic colitis can occur in people of all ages but is most common among children and older people. In North America, the most common strain of E. coli that causes hemorrhagic colitis is E. coli O157:H7. These bacteria naturally occur in the intestines of healthy cattle. Outbreaks can be caused by eating undercooked ground beef or by drinking unpasteurized milk or juice and contaminated water. The disease can be transmitted from person to person, particularly among children in diapers.
E. coli toxins damage the lining of the large intestine. If they are absorbed into the bloodstream, they can also affect other organs, such as the kidney.
Severe abdominal cramps begin suddenly along with watery diarrhea, which typically becomes bloody within 1 to 3 days. The diarrhea usually lasts 1 to 8 days. Fever is usually absent or mild but occasionally can exceed 102° F (38.9° C).
About 2 to 7% of people with hemorrhagic colitis develop a severe complication called hemolytic-uremic syndrome (see see Thrombotic thrombocytopenic purpura (TTP) and hemolytic-uremic syndrome (HUS)). Symptoms include anemia (characterized by fatigue, weakness, and light-headedness) caused by the destruction of red blood cells (hemolytic anemia), a low platelet count (thrombocytopenia), and sudden kidney failure. Some people with hemolytic-uremic syndrome also develop complications of nerve or brain damage, such as seizures or strokes. These complications typically develop in the second week of illness and may be preceded by increasing fever. Hemolytic-uremic syndrome is more likely to occur in children younger than 5 years and in older people. Even without hemolytic-uremic syndrome and its complications, hemorrhagic colitis may cause death in older people.
A doctor usually suspects hemorrhagic colitis when a person reports bloody diarrhea. To make the diagnosis, a doctor has stool specimens tested for strains of E. coli. Sometimes, the doctor performs a stool test to detect the toxin produced by the E. coli. Other tests, such as colonoscopy, may be performed if a doctor suspects that other diseases may be causing the bloody diarrhea.
The most important aspect of treatment is drinking enough fluids. Sometimes so much fluid is lost, however, that a doctor has to replace them intravenously. Antibiotics are not given because they increase the risk of developing hemolytic-uremic syndrome. People who develop complications are likely to require intensive care in the hospital and may need kidney dialysis (see see Dialysis).
Last full review/revision August 2012 by Thomas G. Boyce, MD, MPH