Chickens should not get fleas based on the fact that parasites are very temperature sensitive and don't like to be on a host that has the wrong body temperature. Dog and cat fleas prefer about 101 degrees. A chicken's body temperature is around 105. Humans, on the other hand, are closer to 97 degrees. For that reason, you might find dog and cat fleas on a human or chicken if there is no other food source, but you shouldn't find a flea infestation on them.
Chickens are more likely to have lice or mites. Mites can be red or brown and are very tiny. Lice tend to be a light brown or yellow color. Fleas are larger and darker than lice and mites, so it should be easy to tell them apart.