They can be on the ground...somehow you'll have to break the cycle. I had a spray that interrupted the gestational cycle of the fleas for use in the house. However, not sure of using it around the chickens. There are some things you can use on the dogs, too.
Answer
Chickens will actually eat the ticks, and keep them down, but they can carry fleas and lice and mites. They are really hard to get rid of. It requires consistent battle for quite some time. If you let up, they will come back full force.
Put diatomaceous earth in the places that the chickens dustbathe.
paint their roosts with insecticidal paint.
Clean the entire chicken coop.
Fumigate it. Make sure that the chickens are all out, and that there is enough time for it to air out before they get back. Check the can.
Sprinkle diatomaceous earth or other pesticide all over the floor and in nesting boxes before putting down hay.dust chickens with DE or other safe pesticide.
Keep doing all this for at least 6 mos.