Pubic or “crab” lice are parasitic insects that survive by feeding on human blood.
Pubic lice are parasites different from head or body lice and are usually found in the pubic hair. They can also be found in coarse body hair, such as eyebrows, beard, chest, or armpit hair.
Pubic lice have forms:
- the egg (also called a nit),
- the nymph,
- and the adult.
Nit: Nits are lice eggs. They can be hard to see and are found firmly attached to the hair shaft. They are oval and usually yellow to white. Pubic lice nits take about 6-10 days to hatch.
Nymph: The nymph is an immature louse that hatches from the nit (egg). A nymph looks like an adult pubic louse, but it is smaller. Pubic lice nymphs take about 2-3 weeks after hatching to mature into adults capable of reproducing. To live, a nymph must feed on blood.
Adult: The adult pubic louse resembles a miniature crab when viewed through a strong magnifying glass. Pubic lice have six legs; their two front legs are large and look like the pincher claws of a crab. This is how they got the nickname “crabs.” Pubic lice are tan to greyish-white in colour. Females lay nits and are usually larger than males. To live, lice must feed on blood. If the louse falls off a person, it dies within 1-2 days.
Adult pubic lice are 1.1-1.8 mm in length. Pubic lice typically are found attached to hair in the pubic area. Still, they are sometimes found on coarse hair elsewhere on the body (for example, eyebrows, eyelashes, beard, moustache, chest, armpits, etc.).
Pubic lice infestations (pthiriasis) are usually spread through sexual contact. Dogs, cats, and other pets do not play a role in transmitting human lice.
Where Are Pubic Lice Found?
Pubic lice are usually found in the genital area of pubic hair. Still, they may occasionally be found on other coarse body hair, such as hair on the legs, armpits, moustache, beard, eyebrows, or eyelashes.
Pubic lice on the eyebrows or eyelashes of children may be a sign of sexual exposure or abuse. Lice found on the head is generally head lice, not pubic lice.
Note: Animals do not get or spread pubic lice.
Symptom Overview
Pubic lice can cause itching, blue spots, and sores in the infected area. Grey-white lice or hair nits (the egg form of pubic lice) may also be visible.
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Treatment
Prescription or over-the-counter shampoos or solutions can be used to treat pubic lice.
Warning: Do not use lice medications to eliminate lice in eyebrows and eyelashes.*
1. Wash & towel dry the infected area.
2. Carefully follow the instructions in the package or on the label. Thoroughly saturate the pubic hair and other infested areas with lice medication. Leave the medication on the hair for the time recommended in the instructions. After waiting the recommended time, carefully remove the medication by following the instructions on the label or in the box.
3. Most nits will still be attached to hair shafts following treatment. Nits may be removed with fingernails, tweezers or a fine-toothed comb.
4. Put on clean underwear and clothing after treatment.
5. Clothing, towels, and bedding: Machine-wash and machine-dry the items that the infested person used during the 2-3 days before treatment. Use hot water (at least 130°F) and the hot dryer cycle.
6. Items that cannot be laundered can be dry-cleaned or stored in a sealed plastic bag for two weeks.
7. Inform all sex partners from within the previous month that they are at risk for infestation and should be treated.
8. Avoid sexual contact with a sex partner(s) until you and your partners have been successfully treated and reevaluated to rule out persistent infestation.
9. Repeat treatment in 9-10 days if live lice are still found.
10. Persons with pubic lice should be evaluated for other sexually transmitted diseases (STDs).
*Special instructions for treatment of lice and nits found on eyebrows or eyelashes:
1. If only a few live lice and nits are present, removing these with fingernails or a nit comb may be possible.
2. If additional treatment is needed for lice or nits on the eyelashes, careful application of ophthalmic-grade petrolatum ointment (only available by prescription) to the eyelid margins 2-4 times a day for ten days is adequate. Regular Vaseline* should not be used because it can irritate the eyes if applied.
Prevention of crabs
• Sexual partners should be treated at the same time as the case.
• Wash bedding all clothing, including night clothes and bath towels used while infestation was present in hot, soapy water or dry clean
• testing to exclude other sexually transmitted infections (STIs) is advisable, as people infested with pubic lice will have another sexually transmitted infection.
You can learn more about the risk of contracting an STD by doing a Quiz, the STD Quiz.
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