Phthirus pubis (pubic louse, cosmopolitan crab, Pediculus pubis)

Epidemiology

• most commonly affects teenagers & young adults
• transmission occurs by intimate contact, primarily during sexual intercourse
• can occur after contact with fomites such as clothing, bedding, & towels used by an infected person
• pubic hair grooming associated with pubic lice

Pathology

• found primarily on pubic hairs, but may extend to the chest armpit & facial hair (including eyelashes)

Clinical manifestations

• intensely pruritic lesions & 2-3 mm bite macules (maculae ceruleae) develop at sites of bites
• blepharitis accompanies infestations of eyelashes
• patients may be asymptomatic

Diagnostic procedures

• dermoscopy (case report with image, video)

Management

• topical permethrin 1% or malathion 0.5% kills both lice & eggs
• on eyelids, apply petrolatum for 3-4 days
• oral ivermectin effective (case report)

More general terms

• Phthirus

Additional terms

• lindane (Kwell, Scabene)
• pediculosis; phthiriasis (lice infestation, vagabond disease)
• permethrin (Elimite, Nix)