The bites of crabs cause small bruises, skin changes, redness and severe itching. Infestation with crabs is also known as pediculosis pubis. Pubic lice occur worldwide and only infest humans, mostly adults.
Pubic lice cannot survive without a host for more than 24 hours and, unlike head lice or clothes lice, do not transmit diseases.
The transmission of crabs mainly occurs through close physical contact, especially during sexual intercourse. Infestation with crabs is therefore a sexually transmitted disease (STD). There is no obligation to report crabs in Germany.
What are crabs?
The technical term forcrabs is Phthirus pubis. They are parasites measuring 1 to 2 millimeters with a roundish, grey-white body and six legs. Crabs feed on the blood of humans and take on a rust-red color when they have ingested blood.
The crabs hold on to the hair of the affected person with strong claws at the end of their legs. Crabs have a life expectancy of about three weeks.
Crabs do not infest the hair on the head @ Warren Rosenberg /AdobeStock
During this time, the fertilized females lay up to three eggs a day. The nits stick to the hair shafts of the pubic hair because of the special secretion. New, sexually mature pubic lice emerge from these within three to four weeks.
Pubic lice are mainly transmitted during close physical contact, especially during sexual intercourse. In rare cases, transmission can also occur when people share bed linen, mattresses, towels or clothing (underwear). A lack of personal hygiene favors the transmission of pubic lice.
Crabs prefer to nest in warm and sometimes moist areas of the body with many sweat glands. They therefore mainly infest the pubic hair in the genital and anal area.
However, they also occasionally feel at home in other hairy areas of the body. These include the stomach, chest, armpits and thighs. Occasionally, crabs can be found on the eyebrows, in the eyelashes or in the beard.
It usually takes three to six days after infection before the crabs become noticeable due to severe itching. However, it can also happen that no noticeable symptoms appear at first. Therefore, crabs can sometimes remain undetected and untreated for a long time.
Infestation with crabs is manifested by severe itching in the pubic area, which is unbearable at night. This itching is triggered by an active substance that the blood-sucking pubic lice excrete when they bite the skin.
Other signs of a crab lice infestation are
- Tiny, rusty-brown spots in the underwear (excrement of the crabs)
- Pubic hair stuck together by nits (crab lice eggs)
- Small bruises and rash-like skin changes around the bite sites. The bite sites can become inflamed due to extensive scratching.
If you experience itching in the genital area or suspect that you have itchy skin, you should consult a specialist in skin and sexually transmitted diseases.
He or she will be able to make a diagnosis quite quickly, as pubic lice and their eggs can be seen with the naked eye or a magnifying glass.
If in doubt, he or she can also enlarge the crabs and eggs under a microscope.
Special shampoos, creams, sprays, lotions or solutions are used to treat crabs. These contain the active ingredients pyrethrum or lindane. The patient should apply the product to the infested areas of skin and leave it to work for several hours.
The aim of the substances is to kill the pubic lice and their eggs and prevent them from reproducing . The patient must repeat the treatment after a week to remove newly hatched larvae from any remaining eggs.
If there is a lot of body hair, the patient should also treat the abdomen, buttocks and thighs with these substances. In addition, a complete shave of the pubic and underarm hair and beard on men can be useful.
The affected person should refrain from close physical contact and sexual intercourse until the treatment for crabs has been successfully completed. In addition, family members and partners should also be checked for crabs and treated if necessary. In this way, a renewed mutual infection with crabs can be avoided.
To kill all crabs and eggs, you should wash bed linen, clothing, underwear and towels thoroughly at 60 degrees Celsius.
Crabs on the comforter cover @ Joshua /AdobeStock
Alternatively, you can store the textiles for three days to several weeks in an airtight plastic bag or in the freezer.
The crabs will die after a maximum of 24 hours.
Crabs are an uncomplicated venereal disease that can be treated quickly and without complications.