The crab louse (pubic louse, Phthirus pubis, the "crabs") may be found in men and women of all ages.
Risk factors:
(1) sexual activity
(1a) multiple partners
(1b) homosexual contact in males
(1c) younger age (under 25 years in females)
(2) contact with someone with lice on exposed hairs
(3) contact with a family member (children may acquire from parents)
While the crab louse may be acquired from sexual contact or child abuse, its presence is not definitive evidence for those activities.
Clinical findings:
(1) pruritis
(2) blue spot 2-3 mm in diameter at the site of a bite (as opposed to the red spot of the body louse)
Locations of lice:
(1) pubic hairs
(2) axillary hair
(3) eyelashes
(4) back hair
(5) facial hair
(6) chest hair
Associated disease or complications:
(1) sexually transmitted disease
(2) secondary infection of excoriations
