Pediculosis pubis

Complications are usually as a result of persistent scratching and include thickening of the skin, darkened skin, and secondary bacterial infection including impetigo, conjunctivitis and blepharitis.[1][8]

Pubic lice are usually transmitted from one person to another during vaginal, oral, anal or manual sex, whether a condom is used or not.[4][8][10] One sexual encounter with an infected person carries a high risk of catching pubic lice.[11] In some circumstances transmission can occur through kissing and hugging, and less likely via bedding, clothing and towels. The lice spread more easily in crowded conditions where the distance between people is close, allowing the lice to crawl from one person to another.[1][8]

Infestation on the eyebrows or eyelashes of a child may indicate sexual exposure or abuse.[6]

Crab lice

Pubic lice (Pthirus pubis) have three stages: the egg (also called a nit), the nymph, and the adult. They can be hard to see and are found firmly attached to the hair shaft. They are oval and usually yellow to white. Pubic lice nits take about 6–10 days to hatch. The nymph is an immature louse that hatches from the nit (egg). A nymph looks like an adult pubic louse but it is smaller. Pubic lice nymphs take about 2–3 weeks after hatching to mature into adults capable of reproducing. To live, a nymph must feed on blood. The adult pubic louse resembles a miniature crab when viewed through a strong magnifying glass. Pubic lice have six legs; their two front legs are very large and look like the pincher claws of a crab—thus the nickname "crabs". Pubic lice are tan to grayish-white in color. Females lay nits and are usually larger than males.[6] To live, lice must feed on blood. If the louse falls off a person, it dies within 1–2 days. Eggs (nits) are laid on a hair shaft. Females will lay approximately 30 eggs during their 3–4 week life span. Eggs hatch after about a week and become nymphs, which look like smaller versions of the adults. The nymphs undergo three molts before becoming adults. Adults are 1.5–2.0 mm long and flattened. They are much broader in comparison to head and body lice. Adults are found only on the human host and require human blood to survive. Pubic lice are transmitted from person to person most-commonly via sexual contact, although fomites (bedding, clothing) may play a minor role in their transmission.[4][12]

Pediculosis pubis is an infestation by the pubic louse, Pthirus pubis, a wingless insect which feeds on blood and lays its eggs (nits) on mainly pubic hair. Less commonly, hair near the anus, armpit, beard, eyebrows, moustache, and eyelashes may be involved.[1][2][3] Although the presence of pubic lice is associated with the presence of other sexually transmitted diseases, pubic lice do not spread infectious diseases.[13]

Nit comb

At first, treatment is usually with topical permethrin 1% cream, which can be bought over the counter without a prescription. It is applied to the areas affected by pubic lice and washed off after 10 minutes.[6] Brands of permethrin include 'Lyclear', available in the UK as a creme rinse or dermal cream at 5% strengths.[15][16] In the US, common permethrin brands include NIX, Actin and Elimite.[17]

An alternative is the combination of pyrethrins and piperonyl butoxide, in a topical application, which include the brands Licide, and A-200, Pronto and RID shampoos.[14][18] These medications are safe and effective when used exactly according to the instructions in the package or on the label.[6] To kill newly hatched lice, both treatments can be repeated within the following seven to ten days.[5][19]

European guidelines state alternatives to permethrin as including either the application of 0.2% phenothrin (washed off after two hours), or 0.5% malathion lotions (washed off after 12 hours).[2] The CDC states alternatives as topical 0.5% malathion or oral ivermectin.[14]

Lindane is still used in a shampoo form in some non-European countries. Its licence was withdrawn by the European Medicines Agency in 2008.[2] It may be considered as a last resort in some people who show resistance to other treatments, but is not recommended to be used for a second round of treatment.[2][4] Lindane is not recommended in pregnant and breastfeeding women, children under the age of two years, and people who have extensive dermatitis.[4][6] The FDA warns against use in people with a history of uncontrolled seizure disorders and cautious use in infants, children, the elderly, and individuals with other skin conditions (e.g., atopic dermatitis, psoriasis) and in those who weigh less than 110 lbs (50 kg).[6][20] Carbaryl has been used since 1976 but found to have the potential to cause cancer in rodents and not to be as effective as previously thought. It is either not used at all or its use is restricted.[2][21]

Sexual partners should be evaluated and treated, and sexual contact should be avoided until all partners are better. Because of the strong association between the presence of pubic lice and sexually transmitted infections (STIs), affected people require investigation for other STIs.[6]

Infestation of the eyes is treated differently from other parts of the body. Lice can be removed with forceps or by removing or trimming the lashes.[22] Eyelashes may be treated with a gentle petroleum jelly for occlusion.[22]