I have a microbiology degree:
E. coli is a normal, natural part of our gut flora. However, there are a large number of strains, a small number of which can be pathogenic. Strains spread from one person to another largely through the fecal-oral route. Although large-scale contaminated food outbreaks get lots of media attention, it happens all the time on smaller scales, as evidenced by the fact that people living in the same area tend to have similar populations in their guts. This is why you can go to Mexico, for instance, and pick up a strain that leaves you on the toilet for a few days, while the natives, who are used to it, cope just fine.
Also, Gestalt, Being a vegetarian isn’t all that much of a protection. Norwalk virus, for instance, infamous for cruise ship outbreaks, is also usually spread through the fecal-oral route, but via lettuce and other salad greens. Raw plant food doesn’t have the added protection of cooking to destroy any germs present.