Chicken lice are specialized for eating bird feathers and cannot infest humans. Chicken mites mainly spread via direct contact from bird to bird, though they sometimes hitchhike on human handlers to get to their next host. Although they may temporarily climb on humans, they cannot live on them.
Lice are often highly specialized for their hosts, and even to specific parts of the host species' bodies. Some species of chicken lice are able to live anywhere on the bird due to their ability to consume blood as well as feathers, but this ability does not extend to them being able to live on humans rather than birds. Lice spend their entire lives on their hosts and cannot live long without them. The primary louse that infests humans is not closely related to chicken lice and subsists entirely upon blood.