Enterohemorrhagic E. coli is one of several intestinal types of E. coli that infect animals and humans. The O157:H7 strain is the member of the group most often associated with a particularly severe form of diarrhea and the most common cause of a unique, sometimes fatal syndrome (hemolytic-uremic syndrome [HUS]) that causes kidney failure (although this happens mainly in the very young and old). The bacteria was discovered in 1977, and first reports of infections followed in 1982.

E. coli accounts for about 2% of all cases of diarrhea in the Western world and at least one-third of cases of hemorrhagic colitis, a potentially deadly inflammation of the colon. The bacteria also accounts for the majority of episodes of HUS, especially in children. Ten percent of individuals with E. coli O157:H7 infection develop HUS; 5% of those will die of the disease. Some who...