Symptoms
- Itching
- Lice and nits in the pubic hair
- Gray to blue skin patches (maculae ceruleae, “taches bleues”) at the injection sites
- Reddish brown spots on the underwear
Causes
The blood-sucking crab louse is a wingless insect about 1 to 2 mm long with 6 legs and large foot claws on the 2nd and 3rd pair of legs. Unlike the elongated head louse, it is about the same length as it is wide and looks crab-like. It is found primarily in the pubic hair, but can also migrate and be carried to other areas of the body. It is also found around the pubic hair, on the legs, on the chest, in the armpits, in the beard, on the eyelashes (! ), the brows or in the hair of the head. The female lays about 25 eggs, which are attached to the hair slightly above the skin in the egg case. The larvae hatch within 6-10 days and become sexually mature during 10-17 days. Outside the body, the lice die within 1-4 days. The scientific name of the crab louse was derived by Linnaeus from, Greek for louse. Therefore, it is also referred to as.
Transmission
Crabs are mainly transmitted during direct intimate contact, especially during sexual intercourse. They cannot hop, jump, or fly and are not found on pets such as dogs or cats. Indirect transmission through objects or clothing is also possible, but less likely. Condoms do not protect against infection as they do for many other sexually transmitted diseases.
Complications
Secondary skin diseases and infections can result from scratching. It is known from research that people with crabs are more likely to also have other sexually transmitted diseases, such as syphilis, gonorrhea, HIV, genital herpes, or trichomoniasis. Scabies may also occur concurrently. Social stigma, feelings of disgust and shame among affected individuals. Crabs are not carriers of infectious diseases such as the ticks or body lice.
Risk factors
- Sexual intercourse, changing sexual partners
- More frequent in the cold season
- Body hair
Diagnosis
In the pubic hair, the eggs and egg cases, live lice and bruises on the skin can be seen by the naked eye. Because they are very small, a lamp and magnifying glass can be used to help. Detection is done microscopically and the diagnosis is considered confirmed if live lice or viable eggs are found. Empty egg cases are an indication but not a definite sign of active infestation. Wet combing can improve the reliability of the diagnosis.
Differential diagnosis
- Scabies can be confused with a crab louse infestation. It is a parasitic skin disease caused by burrowing mites that burrow into the skin, multiply, and cause allergic and eczematous skin reactions. Persistent itching occurs especially in bed heat. The mites (0.3 mm), which are much smaller than the lice, live in ducts under the skin and do not lay eggs on the hair.
- Body lice
- Head lice occur only in the hair of the head
- Other skin diseases, eczema
Non-drug treatment
- Regular wet combing of the hair with a nit comb (louse comb) removes the lice mechanically.
- Shaving the hair is effective because the lice need the hair shaft to lay their eggs.
- Children can have their fingernails cut short to prevent scratching.
- The bedding, towels and clothes should be changed regularly and washed well at least 60 ° C. Vacuum regularly. Not recommended to use insecticides (insect sprays) for environmental treatment.
- Until the completion of successful therapy, sexual intercourse and close physical contact should be avoided in order not to infect the partner. The sexual partner from whom the lice were acquired should be informed and treated.
Drug treatment
Notes on drug treatment:
- All parts of the body where lice or eggs are present should be treated. In particular, the area around the pubic region (perianal region, rectal hair) is also important.
- Treatment should be repeated after 7-10 days to kill newly hatched larvae.
- Non-drug measures such as wet combing with a nit comb can increase the success of drug therapy.
Insecticides:
- Malathion (Prioderm, out of trade) was approved in many countries for the treatment of crabs.
- Lindane (Jacutin Gel, off label) was previously approved but is no longer commercially available in many countries and the EU due to the potential for adverse effects and ecological concerns. It should no longer be used. In Germany, Jacutin Pedicul Fluid is on the market. It contains dimeticone and no longer lindane.
Further, those agents can be used off-label, which are also used for the treatment of head lice. However, they are not approved for this indication in many countries:
- Permethrin
- Ivermectin
Silicones:
- Dimethicone is a physically active pediculocide.
Herbal preparations:
- See under head lice
Antibiotics:
- Cotrimoxazole an antibiotic and is sometimes prescribed for lice, but is not approved for this indication. It may work by killing the intestinal flora of the insects. Because of possible adverse effects, it should be used cautiously in exceptional cases or not at all.
Lice in the eyelashes
Lice and eggs in the eyelashes (medical: phthiriasis palpebrarum) can be removed mechanically with tweezers or cut away with scissors. Medicinal treatment includes the use of petroleum jelly to suffocate the insects. It is applied 2 times a day for 7-10 days. Other therapeutic options are described in the literature.
