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Lice: pubic lice  

What is the cause?

Pubic lice or 'crabs' is caused by the pubic louse (or crablouse), Pthirus pubis. These insects are usually found tightly attached to the hairs of the pubic region, less commonly to the hairs of the legs, the underarm or the beard. In young children the lice can occasionally be found on the eyelashes or on the hair of the forehead. Eggs are attached to the hair shaft after being laid. The lice live for about 3 weeks.

How is it spread?

Crablice are transmitted by close personal contact, especially during sexual intercourse. They may rarely be transmitted to young children by contact with heavily infested parents.

What are the symptoms?

There may be no symptoms, but the infestation or itching may be the main complaint. The pubic area may have a musty smell.

How is it diagnosed?

Diagnosis is made by finding eggs or lice tightly applied to the hair shaft. The lice may be seen to move like crabs, but usually are seen as rust-coloured specks in the pubic hair.

What is the treatment?

Topical medication

The treatment of choice is gamma benzene hexachloride 1 per cent lotion. The sexual partner should also receive treatment to prevent reinfection.

Where should it be applied?

Apply to the affected hair only. This is usually confined to the pubic hair.

Where the lice or their eggs are attached to eyelashes, insecticides should not be used; cure can be achieved by the liberal application of Vaseline to the hairs.

How often?

Repeat in 1 week. Sometimes a third treatment is necessary.

Clothing and bedding

Wash off the lotion after 24 hours, then remove pyjamas, underwear, sheets and pillow slips for normal washing in hot water. Repeat this in 1 week.

Copyright 1995: John Murtagh, Professor of General Practice
Monash University, Melbourne, Australia