By Gary M. White, MD
Multiple nits are seen attached to groin hairs.
Pediculosis pubis is an infestation of the groin by the louse Phthirus pubis. This louse has a broad, crab-like body and thick, claw-like legs. It prefers to infest areas where the adjacent hairs are farther apart than scalp hairs, e.g. the eyelashes, beard, chest, axillary region, and pubic region. There is a decreasing incidence because of the shaving and waxing of pubic hair!
The patient complains of itch in the affected areas. S/he may be aware of the infestation and say, "there are things crawling on me". Examination shows both nits on the hairs and small, crab-like creatures clutching the base of two hairs. The groin, chest, abdomen, axilla, perianal area and eyelashes should all be examined.
Small blue/green macules occasionally are occasionally seen. These dusky great blue macules (called tache bleu and maculae cerulae) are 1-3 cm in diameter often may be observed on the trunk, thighs and axilla. They are the result of reaction of the insect's saliva with bilirubin converting it to biliverdin.
OTC treatments are available and include i) permethrin 1% or ii) pyrethrins with piperonyl butoxide. Both are applied to the affected area and washed off after 10 minutes. If there is any question, all potential areas should be treated, i.e., genital and perianal area, thighs, trunk, axilla, mustache and beard. Prescription alternatives include malathion 0.5% lotion (Ovide) applied for 8–12 hours and washed off, oral ivermectin 250 µg/kg, repeated in 2 weeks, and permethrin 5% (Elimite) from the trunk to knees overnight. A fine toothed (nit) comb should be used to remove dead lice and nits. Bedding and clothing should be decontaminated (i.e., either dry cleaned or machine-washed and dried using the heat cycle) or removed from body contact for at least 72 hours. Fumigation of living areas is not necessary. Eyelid infestation should not be treated with any of the above topical agents. See pediculosis, eyelashes.
Retreatment may be needed in 3-7 days. If any one treatment results in failure, another should be tried. Sexual partners within the last 3 months should be treated if possible.
Pregnant women may be treated with either permethrin or pyrethrins with piperonyl butoxide.
Pediculosis may spread all over the abdomen, chest and axilla. Here, nits and crabs are shown in the axilla.
Homepage | FAQs | Contact Dr. White