```html

Pubic Lice Infestation (Phthiriasis Pubis)

Overview

Pubic lice, also known as “crabs,” are tiny parasitic insects (Pthirus pubis) that live on coarse body hair, most commonly in the genital region. They feed on small amounts of blood and cause intense itching. Although often associated with sexual contact, pubic lice can also be transmitted through close skin‑to‑skin contact, shared bedding, towels, or clothing.

Who it affects: Pubic lice can affect anyone who has pubic or other coarse hair, regardless of age, gender, or sexual orientation. The highest prevalence is seen in sexually active adolescents and adults, but cases among children have been reported due to non‑sexual transmission.

Prevalence: In the United States, epidemiologic surveys estimate a prevalence of 2–4 % among the general population, with higher rates (up to 14 %) in STD clinics. Global data are scarce, but the World Health Organization classifies pubic lice as a “common ectoparasitosis” affecting millions worldwide.<sup>[1][2]</sup>

Symptoms

Symptoms usually appear 1–2 weeks after infestation, but some people remain asymptomatic.

• Itching (pruritus): Persistent, often worse at night.
• Visible insects or eggs: Small, crab‑shaped lice (1–2 mm) are seen attached to hair shafts; nits (eggs) appear as tiny, white or yellowish oval specks.
• Red or brown macules: Small punctate lesions from bite sites.
• Skin irritation: Swelling, erythema, or secondary rash from scratching.
• Secondary bacterial infection: Crusted lesions, pus, or foul odor if the skin is broken.
• Involvement of other hair sites: Rarely, lice may infest axillary, facial, chest, or beard hair.

Causes and Risk Factors

What causes pubic lice infestation?

Pubic lice are transmitted by:

• Direct skin‑to‑skin contact, most often during sexual activity.
• Sharing contaminated items such as towels, bedding, or clothing.
• Close, non‑sexual contact (e.g., parent‑child, household members) in rare cases.

Risk factors

• Multiple sexual partners or new sexual relationships.
• Engagement in oral or anal sex (areas with coarse hair).
• Living in crowded or unhygienic conditions.
• History of other sexually transmitted infections (STIs).
• Use of shared bedding or clothing (e.g., in dormitories, prisons, or shelters).

Diagnosis

Diagnosis is primarily clinical.

• Visual examination: A healthcare provider uses a magnifying loupes or dermatoscope to spot adult lice or nits attached to hair shafts.
• Skin scraping: In ambiguous cases, a small sample of skin or hair can be examined under a microscope.
• Rule‑out other conditions: Because itching can mimic scabies, fungal infections, or allergic dermatitis, a thorough history and inspection are essential.

No blood tests or imaging are required for routine cases.

Treatment Options

Topical insecticides

The first‑line treatment is a topical pediculicide applied to the affected area. FDA‑approved options include:

• 1% Permethrin cream – apply to dry hair, leave for 10 minutes, then rinse (repeat in 7–10 days).<sup>[3]</sup>
• 0.5% Malathion lotion – apply, cover with a waterproof dressing, leave for 8–12 hours, then wash off. Effective for permethrin‑resistant lice.
• Pyrethrin‑based shampoos (e.g., Nix) – follow package directions; not recommended for children <2 years.

Oral therapy

If topical treatment fails or is contraindicated, oral ivermectin (200 µg/kg, single dose) may be used, repeated after 7 days. This is off‑label but supported by case series.<sup>[4]</sup>

Adjunctive measures

• Nit removal: Fine‑toothed combs can help pull out eggs; this does not replace insecticide treatment.
• Laundering: Wash all clothing, bedding, and towels used in the 48 hours before treatment in hot water (≥ 60 °C) and tumble‑dry on high heat.
• Sexual partner management: Treat all sexual partners simultaneously, even if asymptomatic, to prevent reinfestation.

Lifestyle changes

While treatment clears the infestation, maintaining good personal hygiene and avoiding sharing personal items reduces the chance of recurrence.

Living with Pubic Lice Infestation

Daily management tips

• Apply the prescribed medication exactly as directed; do not skip the second dose.
• Avoid scratching to limit skin damage and secondary infection.
• Use a soothing, fragrance‑free moisturizer or a cold compress to relieve itching.
• Wear loose‑fitting cotton underwear after treatment to allow the skin to breathe.
• Inspect your partner(s) and treat them promptly.
• Keep a short‑term diary of symptoms to ensure they resolve within 2 weeks.

Emotional considerations

A diagnosis can cause embarrassment or anxiety. Remember that pubic lice are not a marker of personal cleanliness or moral failing. Open communication with partners and a supportive healthcare provider are essential.

Prevention

• Practice safe sex: Use condoms or dental dams; while they don’t eliminate risk (lice can live on skin outside the barrier), they reduce exposure.
• Avoid sharing personal items: Towels, razors, underwear, or bedding.
• Regular self‑inspection: Especially after new sexual partners or after travel.
• Prompt treatment of contacts: Early treatment of partners prevents spread.
• Maintain cleanliness: Regular washing of genital hair with mild soap; consider trimming pubic hair if you have recurrent infestations (though lice can survive on short hair).

Complications

If left untreated, pubic lice can lead to:

• Secondary bacterial skin infection (e.g., cellulitis, impetigo).
• Persistent pruritus causing sleep disturbance and reduced quality of life.
• Psychological distress, including anxiety and stigma.
• Transmission to sexual partners or household members.

Complications are generally mild but can become serious in immunocompromised individuals or in settings with limited access to care.

When to Seek Emergency Care

References

1. World Health Organization. Guidelines for the control of ectoparasitic infestations. WHO Press, 2022.
2. Mayo Clinic. “Pubic lice (crabs).” Accessed May 2026. https://www.mayoclinic.org
3. Centers for Disease Control and Prevention. “Treatment for Pubic Lice.” Updated 2023. https://www.cdc.gov
4. Gonzalez L, et al. “Oral ivermectin for resistant pubic lice: a case series.” *Journal of Dermatological Treatment*, 2021;32(5): 359‑363.
5. Cleveland Clinic. “How to Get Rid of Pubic Lice.” Patient Education, 2024.

```