Pediculosis pubis - Anogenital in
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Synopsis
Epidemiology is difficult to elucidate as the infection is likely under-recognized and can be treated without presentation to a health care provider. However, this condition is more common in sexually active individuals. Lice live on terminal hair, typically in the pubic and perianal regions, although infestations may also be noted in the eyelashes (pediculosis palpebrarum), eyebrows, and other facial hair, as well as chest and axillary hair. Scalp infestation may also be seen in tightly curled hair. The lice are not adapted for crawling.
The incubation time is less than one week from contact, although it has been found to be longer in some cases. The eggs (nits) are cemented to hair shafts with chitin and are difficult to remove. Lice hatch in approximately 6-10 days. The lifespan of the louse is less than 1 month. The lice are not able to survive without feeding within 24 hours.
Although the bites of the lice are thought to be painless, the majority of those infected will present with extreme pruritus; one study suggests up to 86% will complain of pruritus. This is thought to be secondary to a reaction to the saliva and/or the anticoagulant injected into the skin by the louse during feeding.
Codes
ICD10CM:B85.3 – Phthiriasis
SNOMEDCT:
71011005 – Pediculosis pubis
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Differential Diagnosis & Pitfalls
Most commonly, pediculosis pubis is mistaken for another form of infestation.Pediculosis capitis and pediculosis corporis can be distinguished based on the prevailing location of the lice (pediculosis capitis is predominantly on scalp hair, while pediculosis corporis is predominantly identified on clothing) and the physical appearance of the lice (pediculosis capitis, corporis lice are more slender).
Other considerations include:
- Scabies
- Folliculitis
- Other arthropod bites / stings
- Neurotic excoriations
- Delusions of parasitosis
- Irritant contact dermatitis
- Other causes of anogenital itch, including tinea cruris, allergic contact dermatitis, and candidiasis
- Peripilar hair casts – usually scalp hair affected
- Pityriasis amiantacea – usually scalp hair affected
- Trichomycosis axillaris – axillary and pubic hair may be affected
- White piedra – pubic, axillary, and facial hair may be affected
- Black piedra – usually scalp hair affected
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Last Reviewed:12/20/2017
Last Updated:12/20/2017
Last Updated:12/20/2017
Patient Information for Pediculosis pubis - Anogenital in
Overview
Pubic lice (pediculosis pubis), also known as crab lice or crabs, is a louse (a type of wingless, bloodsucking insect) that can live and multiply (infest) on skin that grows pubic hair. Pubic lice most commonly affect the pubic hair, but other hair-bearing areas, such as the armpits and eyelashes, eyebrows, or scalp, may also be affected. The infestation usually causes itching, but it can occur without any symptoms. It is spread by close physical contact or contaminated clothing, bedding, or towels (fomites). Pubic lice infestations may occur with other sexually transmitted diseases.Who’s At Risk
Men are more commonly affected by public lice, possibly because they have more coarse body hair.This infestation is most frequent between the ages of 15–40 in people who are sexually active.
Signs & Symptoms
Lice and their eggs (nits) may attach themselves to the hair in the pubic region and other areas. Lymph nodes in the groin area may be swollen. Slate blue spots may be seen at the bite sites.Self-Care Guidelines
Always use safe sex practices, including avoidance of intimate contact with partners affected with pubic lice.When to Seek Medical Care
See your doctor for evaluation if you think you might have pubic lice.Treatments
Your doctor may:- Treat the infestation with permethrin cream rinse OR pyrethrins with piperonyl butoxide. Treatment with typical insecticides may be repeated after 1 week.
- Try malathion 0.5% lotion OR ivermectin, an oral medication, taken in one dose and repeated after 2 weeks.
- Treat any sex partners you have had within the previous month, as recommended by the Centers for Disease Control (CDC).
Avoid sexual contact until you and your partner(s) have been treated and reevaluated to be sure the infestation is no longer present.
References
Bolognia, Jean L., ed. Dermatology, pp.1326-1328. New York: Mosby, 2003.
Freedberg, Irwin M., ed. Fitzpatrick's Dermatology in General Medicine. 6th ed. pp.2286, 2287-2289. New York: McGraw-Hill, 2003.
Pediculosis pubis - Anogenital in
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