What are pubic lice?
A pubic louse is a small, crab-like parasite that lives among the hairs in the pubic area. They are transmitted through close bodily contact, which is why pubic lice are regarded as a sexually transmitted infection (STI).
What is a pubic louse?
The pubic louse (Phthirus pubis) is a crab-like parasite that lives by preference in the hair of the pubic area. It is sometimes also found in the armpit hair, the beard area or between the eyelashes. It lives on blood, which it sucks (especially in the evening) from the skin near the hair follicles. Throughout its adult life it keeps laying eggs (nits), on average 2 to 3 a day, which hatch after about 10 days; after 2 weeks the young lice are themselves adult and able to reproduce.
What are the signs?
Itch is the main feature; sometimes the skin is scratched open until it bleeds.
How does infection occur?
Pubic lice are transmitted through close bodily contact, in practice almost always sexual contact. The louse cannot survive longer than about 48 hours off the skin, so other routes are not very common, though in theory they could be transmitted via, for example, towels recently used by someone carrying them.
How is the diagnosis made?
Persistent itch in the pubic hair area is the main clue, all the more if the partner develops similar complaints. The small lice are not always easy to see with the naked eye; the small grey-white nits, glued to the pubic hairs, are sometimes more noticeable. When pubic lice occur in the eyelashes, they can cause, besides itch, inflammation of the eyelids (blepharitis), which is fairly common especially in infected children.
How is it treated?
Pubic lice can be treated adequately with the same medicines used for head lice, such as permethrin, available without prescription (read the instructions before use). Bedding and clothing should be washed. Partners must treat themselves at the same time, even without itch, to prevent reinfection. Lice and nits in the eyelashes must not be treated with chemical products; they can be removed one by one with tweezers, or, alternatively, the eyelashes can be treated with petroleum jelly to smother the lice, applied twice a day for 3 weeks.
What is the outlook?
When treatment is carried out correctly, the pubic lice will not return. Because the infection is regarded as an STI, it may be worth having an STI screening (depending on the situation).
When to see a doctor
See a doctor or sexual-health clinic for persistent itch in the pubic area, if you find lice or nits, or if a partner is affected, and consider a full STI check.