[5] In some people, particularly children under five years of age, persons whose immunologies are otherwise compromised, and the elderly, the infection can cause hemolytic–uremic syndrome (HUS), in which the red blood cells are destroyed and the kidneys fail.

The prophage responsible seems to have infected the strain's ancestors fairly recently, as viral particles have been observed to replicate in the host if it is stressed in some way (e.g.

[8] The periplasmic catalase is encoded on pO157 and may enhance the virulence of the bacterium by providing additional oxidative protection when infecting the host.

[citation needed] While it is relatively uncommon, the E. coli serotype O157:H7 can naturally be found in the intestinal contents of some cattle, goats, and even sheep.

[citation needed] The digestive tract of cattle lack the Shiga toxin receptor globotriaosylceramide, and thus, these can be asymptomatic carriers of the bacterium.

[citation needed] Avoiding the consumption of, or contact with, unpasteurized dairy products, undercooked beef, uncleaned vegetables, and non disinfected water reduces the risk of an E. coli infection.

Proper hand washing with water that has been treated with adequate levels of chlorine or other effective disinfectants after using the lavatory or changing a diaper, especially among children or those with diarrhea, reduces the risk of transmission.

[19] While fluid replacement and blood pressure support may be necessary to prevent death from dehydration, most patients recover without treatment in 5–10 days.

[23] The first recorded observation of human E. coli O157:H7 infection was in 1975, in association with a sporadic case of hemorrhagic colitis, but it was not identified as pathogenic then.

[24] It was first recognized as a human pathogen following a 1982 hemorrhagic colitis outbreak in Oregon and Michigan, in which at least 47 people were sickened by eating beef hamburger patties from a fast food chain that were found to be contaminated with it.