Pubic Lice
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Also called
"crabs," pubic lice are parasitic insects found in the genital area of
humans. Infection is common and found worldwide.
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Pubic lice
are usually spread through sexual contact. Rarely, infestation can be
spread through contact with an infested person's bed linens, towels, or
clothes. A common misbelief is that infestation can be spread by sitting
on a toilet seat. This isn't likely, since lice cannot live long away from
a warm human body. Also, lice do not have feet designed to walk or hold
onto smooth surfaces such as toilet seats.
Infection in
a young child or teenager may indicate sexual activity or sexual abuse.
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Pubic lice
are generally found in the genital area on pubic hair; but may
occasionally be found on other coarse body hair, such as hair on the legs,
armpit, mustache, beard, eyebrows, and eyelashes. Infestations of young
children are usually on the eyebrows or eyelashes. Lice found on the head
are not pubic lice; they are head lice.
Animals do
not get or spread pubic lice.
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Itching in
the genital area. Nits (lice eggs) or crawling lice may be seen.
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There are
three stages in the life of a pubic louse: the nit, the nymph, and the
adult.
Nit:
Nits are pubic lice eggs. They are hard to see and are found firmly
attached to the hair shaft.
They are
about the size of the mark at the end of this arrow 
. They are oval and usually
yellow to white. Nits take about 1 week to hatch.
Nymph:
The nit hatches into a baby louse called a nymph. It looks like an adult
pubic louse, but is smaller. Nymphs mature into adults about 7 days after
hatching. To live, the nymph must feed on blood.
Adult:
The adult pubic louse is about this size 
and resembles a miniature crab
when viewed through a strong magnifying glass. Pubic lice have six legs,
but their two front legs are very large and look like the pincher claws of
a crab; this how they got the nickname "crabs." Pubic lice are tan to
greyish-white in color. Females lay nits; they are usually larger than
males. To live, adult lice need to feed on blood. If the louse falls off a
person, it dies within 1-2 days.
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By looking
closely through pubic hair for nits, nymphs, or adults. Finding a nymph or
adult may be difficult; there are usually few of them and they can move
quickly away from light. If crawling lice are not seen, finding nits
confirms that a person is infested and should be treated. Diagnosis should
be made by a health care provider if you are unsure about infestation or
if treatment is not successful.
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A 1%
permethrin or pyrethrin lice shampoo, also called pediculicide
peh-DICK-you-luh-side, is recommended to treat pubic lice. These products
are available with out a prescription at your local drug store. Medication
is generally very effective; apply the medication exactly as directed on
the bottle. A prescription medication, called Lindane (1%) is available
through your health care provider. Lindane is not recommended for pregnant
or nursing women or for children less than 2 years old.
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- Wash the infested area; towel dry.
- Thoroughly saturate hair with lice medication. If using permethrin or pyrethrins,
leave medication on for 10 minutes; if using Lindane, shampoo should only
be left on for 4 minutes. Thoroughly rinse off medication with water. Dry
off with a clean towel.
- Following treatment, most nits will still be attached to hair shafts. Nits
may be removed with fingernails.
- Put on clean underwear and clothing after treatment.
- To kill any lice and nits that may be left on clothing or bedding, machine
wash those washable items that the infested person used during the 2-3 days
before treatment. Use the hot water cycle (130o F) of the washing machine
to wash clothes. Use the the hot cycle of the dryer for at least 20 minutes
to dry clothes.
- Dry clean clothing that is not washable.
- Inform any sexual partners that they are at risk for infestation.
- Avoid any sexual partners until partners have been treated and infestation
has been cured.
- Retreat in 7-10 days if lice are still found.
If only a few
nits are found, it may be possible to remove live lice and nits with your
fingernails or a nit comb.
If additional
treatment is needed for pubic lice nits found on the eyelashes, applying
an ophthalmic- grade petrolatum ointment (only available by prescription)
to the eyelids twice a day for 10 days is effective. Vaseline* is a kind
of petrolatum, but is likely to irritate the eyes if applied.
* Use of
trade names is for identification only and does not imply endorsement by
the Public Health Service or by the U.S. Department of Health and Human
Services.
This fact
sheet is for information only and is not meant to be used for
self-diagnosis or as a substitute for consultation with a health care
provider. If you have any questions about the disease described above or
think that you may have a parasitic infection, consult a health care
provider.
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Andropause
