Yup, chickens will get worms from time to time. But stopping them from eating earth worms is crazy. Anyone that free range chickens knows they will be eating worms, bugs and anything they want and can catch. This is what they ate long before we came up with special diet for them. Do all the preventive measures to keep your chickens healthy and do what you can to get them well if they get sick. But, let them eat what they like. Remember, there is such a thing as over medicating, that is what has cause the super bug in humans.