The head louse is an obligate ectoparasite of humans that causes head lice infestation. Head lice are wingless insects spending their entire lives on the human scalp and feeding exclusively on human blood. A head lice infestation results from the direct transfer of lice from the hair of one person to the hair of another through head-to-head contact. To survive, an adult head louse must feed on blood. An infestation does not result from dirty hair or poor hygiene, and it can occur in hair of any length or condition