Pubic lice
Key points
- Pubic lice are small, six-legged creatures that invade the genital hair region and infest it with their eggs.
- Pubic lice are known scientifically as Phthirus pubis.
- An examination of the external genital region typically reveals small gray-white oval eggs (nits) attached to the hair shaft and may reveal adult lice.
- If another treatment is recommended, it should be done 4 days to 1 week later.
Alternative names
Pediculosis - pubic lice; Lice - pubic; Crabs
Definition
Pubic lice are small, six-legged creatures that invade the genital hair region and infest it with their eggs. These lice can also infest armpit hair and eyebrows, but they are drawn to the pubic region.
Causes, incidence, and risk factors
Pubic lice are known scientifically as Phthirus pubis. Lice infestation is a common sexually-transmitted condition and is found mostly in adolescents. Transmission generally occurs during sexual activity, but it can occur through physical contact with contaminated objects such as toilet seats, sheets, and blankets. Some women have acquired it while trying on swimming suits at a store.
The presence of pubic lice is heralded by moderate to severe itching in the area covered by pubic hair. This itch is frequently worse at night. Because the crab louse requires human blood to survive, it buries its head inside a pubic hair follicle. It excretes a substance into the skin that causes the itching.
Sometimes the bite can cause an inflammatory skin reaction that is bluish gray in color. Although the lice do not cause a rash, the constant scratching and digging can cause the skin to become raw, and secondary infections may develop.
On close inspection, adult lice (1.2 mm in diameter) may be seen. A magnifying glass makes the lice more easily visible, and will show the small egg sacs or "nits" that are attached to the pubic hairs, usually at the base.
Although pubic lice appear to prefer the pubic area, they can also thrive on the eyelashes. In young children, pubic lice may be a cause of blepharitis (an eye infection) and their eyelashes should be examined with a high-powered magnifying glass for evidence of lice.
In addition to pubic lice, there is body lice (Pediculus humanis corporis) and head lice (Pediculus humanis capitis).
Risk factors include:
- Being a sexually-active adolescent
- Having multiple sexual partners
- Having sexual contact with an infected person
- Sharing bedding or clothing with an infected person
Symptoms
- Itching in pubic hair region
- Eggs (nits) or actual adult lice may be seen
- Genital lesions due to bites
- Other genital lesions consisting of scratched areas and possibly secondary infections
Written and revised by
Andrey Nailor, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
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