I just learned that the CDC has announced two outbreaks (one, two) caused by different strains of E.coli 0157 H7. The food vector has not been identified in either case. In both cases the CDC recommends:
Washing hands
Cooking meals thoroughly
Avoid cross contamination
Wash fruit and vegetable
Avoid raw milk, other unpasteurized dairy products, and unpasteurized juices
Additionally if you show symptoms of E. coli 0157 H7 please seek medical assistance.
Check out my series on the five CDC foodborne illness risk factors for more information on how to limit food poisoning if you are producing food.