Small, wingless insects that feed on human blood. There are 3 species: (the head louse), (the body louse), and (the crab, or pubic, louse). All have flattened bodies and measure up to 3 mm across. Head lice live on the scalp and their bite causes intense itching. They are spread by direct contact. Their tiny eggs (nits) attach to hairs close to the scalp. Body lice live and lay eggs on clothing next to the skin. They can transmit epidemic typhus and relapsing fever. Crab lice live in pubic hair or, more rarely, in armpits, beards, or eyelashes; they are usually transmitted during sexual contact (see pubic lice). Various preparations can be applied to kill lice and eggs.


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