Endotoxins produced by the bacteria are responsible for the symptoms.
The incubation period is 24 to 72 hours. In adults, the infection is usually not severe, but in children and infants, the infection frequently requires hospitalization, and in some cases is life threatening. Risk factors include recent family illness with E. coli, recent family illness with gastroenteritis symptoms, recent travel to an area endemic for E. coli, or exposure to untreated or contaminated water. The incidence is 3 out of 10,000 people.