Description and Size
Pubic Lice “Crab Lice”
Adult pubic lice are 1.1–1.8 mm in length. Pubic lice typically are found attached to hair in the pubic area but sometimes are found on coarse hair elsewhere on the body (for example, eyebrows, eyelashes, beard, mustache, chest, armpits, etc.). Pubic lice infestations (pthiriasis) are usually spread through sexual contact. Dogs, cats, and other pets do not play a role in the transmission of human lice. An infestation can be avoided by not having sex or by having sex only with one uninfested partner. Pubic lice can also be contracted from bedding and towels used by an infested person, so it’s important to avoid contact with any item – including clothing – that a person who’s infested has used.
Head Lice
Adult head lice are roughly 2–3 mm long. Head lice infest the head and neck and attach their eggs to the base of the hair shaft. Lice move by crawling; they cannot hop or fly. Head lice infestation, or pediculosis, is spread most commonly by close person-to-person contact. Dogs, cats, and other pets do not play a role in the transmission of human lice. Although they are a nuisance, they do not transmit any known diseases. Personal hygiene or cleanliness in the home or school has nothing to do with getting head lice. The egg of the lice is called a “nit” and are cemented to hair shafts and are very unlikely to be transferred successfully to other people. Many nits are more than ¼ inch from the scalp. Such nits are usually not viable and very unlikely to hatch to become crawling lice, or may in fact be empty shells, also known as ‘casings’.
Body Lice
Adult body lice are 2.3–3.6 mm in length. Body lice live and lay eggs on clothing and only move to the skin to feed. Body lice are known to spread disease. Body lice infestations (pediculosis) are spread most commonly by close person-to-person contact but are generally limited to persons who live under conditions of crowding and poor hygiene (for example, the homeless, refugees, etc.). Dogs, cats, and other pets do not play a role in the transmission of human lice. Improved hygiene and access to regular changes of clean clothes is the only treatment needed for body lice infestations.