E. coli is a common kind of bacteria that lives in the intestines of animals and people. There are many strains of E. coli and most do not cause serious illness. However, there are some strains that produce a toxin that can cause severe illness.
These strains are called “shiga toxin-producing E. coli”. E. coli 0157:H7 is the name of one of the most common toxic strains of this type of bacteria. It is found in the intestines of some cattle, deer, goats and sheep.