People – mainly young people – catch pubic (or crab) lice as a result of intimate contact. The parasites can infest any hirsute area of the body, but mainly the pubic area. Their bites cause bad itching. Pubic lice can be treated successfully with anti-lice products.
At a glance
- Pubic lice are mainly transmitted through sexual contact.
- The parasites feed on human blood which they suck from hirsute areas of the skin.
- Bites from crab lice cause itching in the intimate area, but also in the armpits and other hirsute parts of the body where the lice have nested.
- They are diagnosed by the doctor finding the lice and nits in the hair. The naked eye is usually enough to see them.
- There are special creams and shampoos for killing off public lice. Bedding and clothes should be washed with a hot wash.
Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.
What are pubic lice?
Pubic lice – also known as crab lice or crabs – are parasites that nest in hirsute areas of the skin, mainly in the pubic area. Other parts, such as the armpits, legs, chest, eyelashes, eyebrows, beard and head hair can also be affected.
Pubic lice are normally transmitted via intimate contact. So they are classified as a sexually transmitted infection (STI). More rarely, they are passed on via clothing, bedding, or towels.
When the lice come into contact with hirsute skin, they lay their eggs there and suck blood. Anti-lice creams or shampoos are an effective treatment.
What are the symptoms of pubic lice?
Three things indicate that pubic lice have nested:
- (severe) itching
- claw marks
- small blue spots
Small spots of blood may also appear on underwear. They are caused by the lice biting.
It is the louse saliva that causes the itching: the lice excrete it when they bite to prevent the blood from coagulating. The itching can be worse at night.
Severe scratching leaves typical marks on the skin. The scratched areas of the skin can cause skin infections. The lymph nodes near to the scratched areas, for example the groin, sometimes swell up, too.
If the infection lasts for a period of time small, gray/blue spots appear on the skin – like small bruises. They can be up to fingernail size.
If the eyelashes are infested by lice, too, the eyelids swell up and become inflamed. Conjunctivitis may also develop.
How are pubic lice transmitted?
Pubic lice are passed on via close physical contact, but mainly through intimate contact with an infected person. They can also be transmitted if someone shares bedding or clothes with someone who has pubic lice.
The risk of infection also increases if sexual partners are changed frequently.
How common are pubic lice?
Pubic lice are common throughout the world, but there are no exact figures. Infection rates have fallen substantially over recent years. This is thought to be because of the increase in intimate shaving.
How can pubic lice be prevented?
As with other sexually transmitted infections, prevention depends largely on one’s own sexual behavior.
In general, the best protection is to avoid close contact with anyone who has crabs. If someone in the household has pubic lice, clothing, towels and bedding, for example, should be washed on a hot wash before being used by others.
Apparently shaving the intimate area and the armpit hair makes it difficult for the parasites to nest there. But shaving does not provide reliable protection.
How are pubic lice diagnosed?
They are diagnosed by the doctor finding the lice and eggs (nits) on the hair shaft. This can be done with the naked eye, but it is easier with a magnifying glass or microscope, because the lice are only around one millimeter in size and do not move a lot.
If pubic lice are suspected, the eyelashes, eyebrows and any other hirsute areas of the body should be examined for the parasites, too.
How can one get rid of pubic lice?
A pubic lice infection can be easily treated. The aim is to get rid of the lice and eggs.
The easiest way is to shave the hair off the affected body part and to take some other hygiene measures. However, one can also get rid of them by treating them with an anti-lice product.
Local treatment is administered using special shampoos or creams. These contain chemicals that kill insects (insecticides) and they are applied to the areas affected. It is best to treat all the hirsute areas of the body except for the eyelashes and eyebrows.
Products like these usually contain agents such as permethrin and pyrethrin. These two substances are also used to treat head lice. In the case of pubic lice, the product is usually applied to the affected areas and left for a few minutes, as indicated by the instructions, so that it can take effect.
After treatment, nits and lice should be combed out using a special comb (nit comb), and fresh clothing should be put on. Alternatively, the parasites and eggs can also be removed using one’s fingernails or tweezers.
If the itching continues a week after the first treatment, or if lice or eggs are still being found, the treatment should be repeated. In this case, it is then best to try a different product.
Important: Infested eyebrows and eyebrows should not be treated with anti-lice products, as they can harm the eyes. In this case, the lice and eggs can easily be removed with tweezers. Or the lice can be suffocated by applying a fatty ointment like Vaseline to the eyelashes and eyebrows, and then removing the nits and lice. The eyebrows can be shaved, too.
Treatment for sexual partners
Sexual partners should also be treated with anti-lice products and close contact should be avoided until the treatment has finished.
People with whom one has had sexual contact during the previous 3 months should be told and they should get examined for pubic lice.
People living in the same household as anyone infected, but who have had no sexual contact with them and who have no symptoms do not need to be treated.
Bedding, towels and clothes need to be machine-washed at at least 60 degrees, and dried in a hot drier if there is one. Chemical cleaning is also effective.
If there is no way to wash the things or to get them cleaned chemically, they can be packed into plastic bags. After 48 hours without any blood to feed on, the lice die off. Bagging up items for 2 weeks prevents freshly hatched lice from forming new nests.
The home in which people with pubic lice are living does not need to be specially cleaned.
- Deutsche STI-Gesellschaft (DSTIG), Ärztliche Gesellschaft zur Gesundheitsförderung e.V. (ÄGGF), Bundesverband der Kinder- und Jugendärzte e.V. (BVKJ) et al. Sexuell übertragbare Infektionen (STI) –Beratung, Diagnostik und Therapie. AWMF-Registernummer 059 – 006. 08.2018.
- DynaMed (Internet), Ipswich (MA). Pediculosis Pubis and Pediculosis Corporis. EBSCO Information Services. Record No. T114055. 2018 (1995). Aufgerufen am 22.01.2021.
- Dholakia S, Buckler J, Jeans JP et al. Pubic lice: an endangered species? Sex Transm Dis. 2014 Jun;41(6):388-91. doi: 10.1097/OLQ.0000000000000142. PMID: 24825336.
- UpToDate (Internet). Pediculosis pubis and pediculosis ciliaris. Wolters Kluwer 2020. Aufgerufen am 22.01.2021.
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