Pubic lice

Definition

A species of sucking louse, Pthirus pubis (family Pthiridae), that infests human pubic hair and occasionally other coarse body hair; characterized by a short, broad crab-like body and strong claws adapted for grasping hair shafts. The infestation (pediculosis pubis) is primarily transmitted through sexual contact but may spread via shared bedding, clothing, or towels.

Etymology

Example

In clinical practice, pubic lice nits are often detected attached to the base of pubic hair shafts, appearing as tiny tan or white ovoid capsules that resist easy removal—unlike dandruff or hair casts—prompting differential diagnosis from other genital dermatological conditions.

Synonyms

• crab louse
• crabs (colloquial)

Related Terms

• Pthirus pubis
• Pthiridae
• Pediculosis
• Head lice
• Body lice
• Phthiraptera
• Ectoparasite
• nit

Usage Notes

The term refers specifically to the species Pthirus pubis, not merely any louse found in the pubic region; other louse species (e.g., Pediculus humanus capitis) may occasionally infest atypical sites. 'Crab louse' is the traditional synonym reflecting the species' dorsoventrally flattened, crab-like morphology with laterally extended legs. In epidemiological contexts, pubic lice infestations are classified as sexually transmitted infestations (STIs), though this classification does not apply to head or body lice.