Women's Conditions / Sexually Transmitted Diseases

Pubic Lice

These lice are wingless insects with six legs and a square body. They look like sea crabs, which is why they are often referred to as “the crabs.” The lice cling to pubic hair and feed on blood. The female of the species lays about 50 eggs, called nits, and attaches them to the base of a hair strand. The average life-span is 25 to 30 days.

There has been a resurgence of pubic lice that parallels increasing rates of other sexually transmitted diseases.

• Risk factors: You are more likely to get pubic lice if you or your partner have multiple or casual sexual partners. It's easier to get lice than any other STD. From just one sexual encounter with an infested person, you have a 95 percent chance of picking them up.

Named for their crab-like appearance, pubic lice are large enough to be visible, and leave little bluish marks where they bite. If your sexual partner has lice, you have a 95 percent chance of picking them up. Some of the old wives' tales are true, too. You can catch lice from dirty sheets and towels, though not from toilet seats.

• Signs and symptoms: You will know if you have contracted pubic lice because you can see them. You may also see little bluish marks in the pubic area or thighs where they've bitten you. The lice often cause itching, which is thought to be from an allergic reaction to their bites. Although crabs are found most often in the pubic area, they can be found on any other hairy part of the body, such as the chest, armpits, beard, and eyelashes. They normally leave the hair on the head to their cousins, body lice.

• Cause: Pubic lice is caused by a parasite known as Phthirus pubis that is transmitted by close body contact, most often by sexual intercourse. Since the lice can live away from their host for 24 to 48 hours, there are other possible modes of transmission such as sheets and towels (but not toilet seats).

• Incubation period: Eggs hatch in seven to 10 days. But depending on the number of lice transmitted, it could be two to four weeks before you notice anything.

• Possible health affects: Having pubic lice raises the suspicion of other STDs.

• Diagnosis: You can tell if you have pubic lice just by looking for them. This is how your doctor will diagnose them.

• Treatments: Shaving the hair is unnecessary. Recommended treatment regimens are either a 1 percent lindane shampoo (Kwell), applied for four minutes and then washed off, or a 1 percent permethrin cream rinse (Rid) which is washed off after 10 minutes. Both of these pesticide treatments require a prescription, with lindane being the less expensive. Lindane should not be used by people with extreme dermatitis because it could cause seizures.

You can buy other pesticide treatments, containing pyrethrin with piperonyl butoxide (A-200, Rid), without a prescription. They are applied for 10 minutes and then washed off. If you are allergic to ragweed, you should avoid these products. There are also products for inanimate objects such as furniture. These should not be used on humans or animals.

If you have lice clinging to your eyelashes, do not use any of these pesticide treatments to get rid of them. Instead, put some Vaseline on the edges of your lids twice a day for 10 days, which will smother the lice. You can also pluck them and the nits off with tweezers.

• Follow-up: You should be re-examined after a week if the lice do not disappear. It is normal to still feel itchy for several days after treatment. All sex partners from the last month should be notified and treated. Avoid sexual contact until the lice and nits are gone. Clothing and bed linen used in the two days prior to treatment should be washed and dried, or dry cleaned.

• Prevention: There is no certain prevention, but since lice are mostly spread in environments where there is lack of good hygiene, avoid using unclean towels, bedding, or clothing. Using a latex condom will not protect you from pubic lice because it does not cover the pubic hair

• Pregnancy: Pregnant or breastfeeding women should not use lindane shampoo or a pesticide containing pyrethrin with piperonyl butoxide.

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