Where is Escherichia coli 0157:H7 primarily found?

Escherichia coli O157:H7 is primarily found in the intestines of humans and animals, particularly cattle. This bacterium is a specific strain of E. coli that can be harmful and is often associated with foodborne illnesses. The connection to ruminant animals, especially cows, is particularly significant because they can carry the strain without showing symptoms, leading to potential contamination of food products, especially undercooked ground beef.

While E. coli can be found in the environment, including water and soil, its most impactful reservoir is the intestines where it resides as part of the normal flora, but in the O157:H7 strain, it can also cause serious health issues upon transmission to humans. Contamination can occur through fecal matter entering water sources or through direct contact with contaminated surfaces, but the initial presence of this pathogen is in the intestines of animals. The air generally does not harbor E. coli O157:H7, as it does not survive well outside of a host environment.