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The STI Files: Pubic Lice

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Stat: There are about 3 million new cases of pubic lice treated in the United States each year.

What is it exactly? Pubic lice is also called "crabs." It is caused by very tiny insects that live in the pubic hair and feed on human blood. The scientific name for pubic lice is Pediculosis pubis. Pubic lice are not the same as body lice.

About how many people have it? There are about 3 million new cases of pubic lice treated in the United States each year. It is unknown how many people have it at any one time.

How is it spread? Pubic lice are often spread through sexual contact, though genital contact or sexual intercourse is not necessary for transmission. In a few cases, pubic lice have been spread through contact with bed linens, towels, or clothes because lice can live for 24 hours off a human body. It is unlikely, though, that this can be spread by toilet seats because lice do not have feet designed to walk or hold on to smooth surfaces.

Animals do not get or spread pubic lice.

What are its symptoms? The primary symptom is itching in the pubic area. The itching is caused by an allergic reaction to the lice bites and usually starts within 5 days after infection. Some people get blue spots where they were bitten.

Scratching may spread the lice to other parts of the body with coarse body hair, such as hair on the legs, armpit, mustache, beard, eyebrows, and eyelashes.

How is it diagnosed? Self diagnosis is possible, but difficult. May require microscopic examination of a skin scraping or biopsy.

Is it treatable? Yes. There are lotions and shampoos that will kill pubic lice. You can get these from a doctor or at a drug store. Some of the medications in these products should not be used by pregnant women, breast feeding women, or young children. Be sure to check with your doctor if you have any questions.

When a person uses these medications, they must also clean anything that might have lice on it. They should put on clean cloths and wash all dirty clothes, bed linens, and towels in very hot water. If something can't be washed, it needs to be put in a sealed plastic bag for 2 weeks to make sure the lice are killed.

The person might still itch even after the lice have been killed because the skin takes time to heal. Something like calamine lotion may help during this time.

Is it curable? Yes, but you can get infected again. If you are infected, make sure all of your sexual partners are treated at the same time that you are treated.

Can it affect fertility? There are no known effects of pubic lice on fertility.

Can it cause death? Pubic lice do not cause anything more than discomfort and inconvenience, though people who scratch the bites may get more bacterial infections.

How can we protect against it? The vast majority of public lice cases occur from sexual contact, so the best way to avoid public lice is to abstain from genital contact. Unfortunately for people who do participate in genital contact, there are no known ways to protect from public lice, including condoms. It is very rare for two people who have been checked by a doctor and only have sex with each other to get pubic lice.

Want to find out about other STIs?

written 29 Apr 2007 . updated 13 Dec 2012

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