MOST US SUPERMARKET CHICKENS INFECTED. “A 2006 study by Consumer Reports found that a staggering 83 percent of grocery market chickens it tested were infected with either campylobacter or salmonella bacteria or both … due largely to the filthy conditions in the sheds where they are raised.”
http://www.peta.org/issues/animals-used-for-food/factory-farming/chickens/chicken-industry/