Crabs

Crabs are parasites. Crabs are often referred to as pubic lice and are not to be confused with body lice. The scientific name for crabs is Pediculus pubis. Crabs need blood to survive, but they can live up to 24 hours off a human body. Crabs have three very distinct phases; egg, nit (egg or young louse), and adult louse. The louse is the stage of the parasite that causes itching. Louse is the singular for lice (like mouse and mice).

How common are they?

In the United States, there are an estimated 3 million cases of crabs every year.

How do people get crabs?

Sexual transmission - You can get crabs when you have skin-to-skin contact with another person. Even when there is no sexual penetration, you can get (or give) crabs.

Non-sexual transmission - You can get crabs from sleeping in an infested bed or using infested towels.

What are the signs or symptoms of crabs?

The most common symptom of crabs is itching in your pubic area. The itching is caused by an allergic reaction to the bites, and usually starts about five days after you get crabs.
If you have crabs and look closely enough in your pubic area, you may see small crab-like parasites that may be whitish-gray or rust colored.
Crab eggs are small and oval-shaped. They are attached to the base of the hair (close to where it comes out of your body).
You may see "blue spots" for several days; these are the result of the bites.
Crabs are usually found in your pubic area; however, you may find them in your armpits, eyelashes, beard/mustache and sometimes in the hair on your head.

How are crabs diagnosed?

You can usually see the crabs yourself if you look closely enough. The adult pubic louse resembles a miniature crab which has six legs, but their two front legs are very large and look like the pincher claws of a crab; this is how they got the nickname “crabs”. You might need a magnifying glass to help you identify them. If you are uncertain, have a health care provider examine you. He or she may need to use a microscope.

What is the treatment for crabs?

There is a cream rinse, called premethrin, which you apply to the affected area and wash off after 10 minutes. Another option is lindane (also known as kwell). This is a shampoo that you leave on for four minutes then wash off. If you are a pregnant or a breast-feeding woman, do not use kwell. Do not use kwell on children under the age of 2. After you are cured, you may still have some itching as a result of a skin irritation or allergic reaction. If so, you can use hydrocortisone cream. You will also need to wash and dry all your clothes, bed linens, sleeping bags, etc. in hot water (at least 125-degrees F). Clothes and other items that cannot be washed can be placed in a plastic bag for two weeks. Repeat treatment in 7-10 days if lice are still found.

How can crabs be prevented?

Abstinence (not having sex).
Mutual monogamy (having sex with only one uninfected partner).
Limit the number of sex partners to reduce your risk of all STDs.
Use latex condoms for all types of sexual penetration (oral, vaginal, anal). Note: Latex condoms, when used consistently and correctly, can reduce the risk of transmission of other STDs, but are not considered effective against crabs.
Know your partner(s). Careful consideration and open communication between partners may protect all partners involved from infection.
Have regular check-ups if you are sexually active.
If you have an STD, don't have sex (oral, vaginal, or anal) until all partners have been treated.
Prompt, qualified, and appropriate medical intervention and treatment and follow-up are important steps in breaking the disease cycle.

Why should I worry about having crabs?

Should I tell my partner?

Yes. Telling a partner can be hard. It's important that you talk to your partner as soon as possible so she or he can get treatment. Also, it is possible to pass crabs back and forth. If you get treated and your partner doesn't, you may get infected again. You will need to wash all clothes, sheets, towels, etc. in hot water (at least 125-degrees F).

Should I tell my healthcare provider that I had crabs?

Where can I get more information?

Illinois Department of Public Health
HIV/STD Hotline 800-243-2437 (TTY 800-782-0423)

Centers for Disease Control and Prevention (CDC)
CDC-INFO Hotline (24 hours, 7 days a week)
STD information and referrals to STD Clinics
800-CDC-INFO (800-232-4636)
TTY: 888-232-6348
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