Crabs

Crabs are a common infestation of parasites that attach themselves to coarse hair (eyelashes or eyebrows or chest, facial, armpit, or pubic hair). People are usually infested by them from sexual contact. Crabs are also known as pubic lice and are caused by the parasite Phthirus pubis. The scientific name for an infestation of the parasite is Pediculus Pubis. Crabs feed on blood but can survive off a human body for about twenty-four hours.

While crabs come from the same family of parasites that cause body and head lice, they are not the same thing. Crabs have three distinct phases. The first phase is the nit (crab’s egg). The second phase is the nymph (immature form of the adult), and the third stage is the louse (adult crab). Crabs can be treated and cured with shampoos and lotions.

Transmission

Crabs can be transmitted by coming in contact with coarse hair (eyelashes or eyebrows or chest, facial, armpit, or pubic hair) infested with them. Usually crabs do not infest head hair.

Sexual contact is the most common way crabs are transmitted. No sexual penetration or body fluid exchanges need to be involved. Transmission of crabs occurs when they move from the coarse hair of one person to the coarse hair of another person.

Crabs can also be transmitted through sleeping in infested bedding, using infested towels, or wearing infested clothing. However, this is less common, because crabs can only live outside the human body for about twenty-four hours. Getting crabs from a toilet seat is rare because their feet are not designed to walk or hold onto smooth surfaces like toilet seats.

Crabs infestations in young children could be a sign of sexual abuse, and infestations in teenagers could be a sign of sexual activity.
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Symptoms

The most common symptom of crabs is itching in the genital area which usually starts about five days after being infested with them. This itching is caused by the body having an allergic reaction to crab bites. Crab bites can also cause dark or bluish spots that last for several days.

People with crabs may be able to see them by looking closely or using a magnifying glass. They have six legs, but the two front legs are larger like the pincher claws of a real crab, which is why they are named crabs. They can be whitish gray or tan in color. People with crabs may also be able to see nits (crab eggs) attached to the base of their hair in the infested area. The nits are small and oval shaped, and can be yellow or white in color.

While crabs are usually found in public hair, they can also be found in eyelashes or eyebrows or chest, facial, armpit, or pubic hair. Rarely, they will be found in head hair.
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Testing / Diagnosis

Crabs can be diagnosed by people visually examining themselves and seeing crabs or nits (crab eggs) in their hair. Using a magnifying glass can help. If someone is unsure whether or not they are seeing crabs or nits, they can visit a health care provider who can make the diagnosis.
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Treatment

There are several options available to kill crabs. A pediculicide (lice-killing shampoo) made of 1% pyrethrin or permethrin is recommended and available over the counter. It should be applied to the infested area for ten minutes, and then washed off. However, it should not be applied to eyelashes or eyebrows. Lindane shampoo (Kwell®) is available by prescription. It should be applied to the infested area for one minutes, then thoroughly washed off. However, it should also not be applied to eyelashes or eyebrows. Furthermore, it should not be left on for more than one minute, and not be used by pregnant or lactating women, young children, people with seizure disorders, or used on broken skin. For eyebrows and eyelashes, there is an ointment available by prescription.

It is important to remember, with any medication, over the counter or prescription, always follow the directions on the label or the instructions given by the prescribing health care provider.

These treatment options can and should kill the crabs. Most of their nits will remain and can be removed with fingernails or a fine tooth comb. After treatment, people should make sure to use clean bedding, clothing, towels, etc. If they do not, they could become infested again.
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Complications

Crabs do not cause any major complications. The worst that can occur is a secondary infection to people who aggressively scratch at the itching.
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Prevention

To avoid being infested with crabs from sexual contact, abstaining from sexual contact is the surest way. A mutual monogamous relationship with a trusted partner known to not be infested is another.

Latex condoms will not prevent the transmission of crabs since crabs live in the pubic hairs. Condoms should still be worn because they can reduce the risk of most other sexually transmitted diseases (STDs).

People who are infested with crabs and get treated should machine wash any bedding, clothing, towels, etc they had used during the two to three days preceding treatment to kill any crabs or nits (crabs’ eggs) left on those items. A hot water cycle (130 degrees F) should be used, and a hot dryer cycle should also be used. Items that can not be washed should be dry-cleaned or placed and sealed in a plastic bag for two weeks. Furniture and living areas do not need to be decontaminated, but if it is desired, they can be vacuumed or treated with a spray that has an agent active against crabs.

Those people infested should also tell any sexual partners to check for crabs and get treated.
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