Crabs, or pubic lice, are tiny, barely visible parasites (scientific name Pthirus pubis ) that live in the pubic area and cause itching. ("Lice" is plural; the singular is "louse"). Pubic lice are commonly called crabs because they are shorter and rounder than head lice and body lice, making them resemble crabs. They are usually found in the pubic hair, but can also be found in other body areas with short hair (eyelashes, eyebrows, armpits, mustache).

Crabs are parasites that can infect the human body. They are spread by personal contact, usually during sexual activity. They may be spread by sharing personal items, such as bedding, towels, and clothing, but this form of transmission is less common.

A risk factor is something that increases your chance of getting a disease or condition.

•  Sexual contact with people who have crabs

•  Contact with contaminated items, such as:

•  Bedding

•  Towels

•  Clothing

•  Toilet seats

•  Furniture

Symptoms include:

•  Itchiness (can range from mild to severe)

•  Tiny blue-gray bumps stuck to the skin called macula caerulea

•  Skin breaks and possible infection (caused by scratching)

The doctor will ask about your symptoms and medical history, and perform a physical exam. The doctor will examine your pubic area for lice and lice eggs (called nits) and macula caerulea. Because 33% of patients with crab lice have other sexually transmitted diseases (including HIV infection), your doctor may choose to do other blood, vaginal/cervical, and/or urine tests.

Treating crabs involves applying over-the-counter shampoo containing insecticide, such as permethrin or Lindane. (Note: Lindane should not be used by pregnant or nursing women or on children under the age of 2.)

Treatment steps are as follows:

•  Wash the infested area, and then towel dry.

•  Thoroughly saturate hair with lice medication. If using permethrin or pyrethrins, leave medication on for 10 minutes. If using Lindane, leave on for only 4 minutes.

•  Thoroughly rinse off medication with water. Dry off with a clean towel.

•  Following treatment, most lice eggs will still be attached to hair shafts. You can remove them with your fingernails or tweezers.

•  Put on clean underwear and clothing after treatment.

•  If you have lice in your eyebrows, you may be directed to coat your eyebrows thoroughly with petroleum jelly.

•  To kill any lice and nits that may be left on clothing or bedding, wash these items that the infested person used during the 2-3 days before treatment. Use the hot water cycle (130 o F) of the washing machine to wash clothes. Use the hot cycle of the dryer for at least 20 minutes to dry clothes.

•  Dry clean clothing that is not washable.

•  Avoid any sexual partners until partners have been treated.

•  Retreat in 7-10 days if lice are still found.

To reduce the chance of getting crabs or spreading crabs:

•  Limit sexual partners.

•  Watch for signs of crabs, such as itching in the genital area.

•  If you or someone in your house has had crabs, thoroughly wash and dry bedding, towels, clothing, and vacuum carpeting and upholstered furniture.

•  If you have had crabs, inform any sexual partners that they are at risk for crabs, and avoid sexual activity until partners have been treated.