Scabies - symptoms and treatment

Scabies is caused by a small, eight legged mite called Sarcoptes scabiei. Scabies is spread by close physical contact and is common in school-age children. If left untreated, it will usually spread to all members of a child's family. The mites and their eggs may live on clothes or bed linen for 1-2 days.

Signs and symptoms

It is often difficult to diagnose scabies because the symptoms vary and the signs can be very subtle.

Commonly, the symptoms include:

Bullae- raised, clear fluid-filled spot or lesion that are bigger than 1cm in diameter.
Papules- solid, raised areas of skin with distinct borders less than 1cm in diameter.
Pustules- raised, fluid-filled spot that appear yellow.
Vesicles- raised, clear fluid-filled spots.

Lesions or spots are areas of skin disease and are generally small.

A number of mites burrow into the skin, particularly between the fingers, around the wrists and elbows, the armpit, nipples and penis. In infants and young children, there are often vesicles and pustules on the palms and soles and sometimes on the scalp. It is the allergic reaction to these mites that causes the rash and symptoms.

Sometimes the only symptom is an itch, without a rash. Usually the itch is worse at night and after a hot bath or shower. Bathe your child in warm water as hot water may make the itching worse.

Your doctor may make a diagnosis by scraping a burrow and looking at that skin under a microscope. Scabies may be easier to diagnose by rubbing a black marking pen over a suspected burrow and then wiping it off with an alcohol swab. This leaves a burrow outlined with the ink from the pen.

Treatment

The child and all close contacts should be treated at the same time.
5% permethrin cream is recommended and should be applied to all body surfaces from the neck down (paying particular attention to hands, under the nails and the genitals) and left on overnight. This treatment can be bought from a pharmacy.
Treatment should be repeated a second time, 1 week later.
In young babies, 6% precipitated sulphur is preferred.
In central and northern Australia, in infants (children less than 1 year of age) and older people, scabies above the neck is common. This means treatment should also be applied to the face and hair (carefully avoiding the eyes, nose and mouth).
Bedding and clothing should be washed in hot water and if possible, dried in a machine on a hot setting.
Items that cannot be washed and dried this way can be put in air-tight containers or bags for 36 hours or in the freezer for a couple of days.
Infected children can return to school when 2 treatments, 1 week apart, have been completed.

Do not apply the initial treatment more than twice. The itching caused by scabies may take up to 3 weeks to go away after treatment. In fact, the treatment itself may cause some irritation. Your doctor can prescribe a corticosteroid cream for this if needed.

Sometimes nodules (raised, solid lesions) caused by scabies can last for months, even with the corticosteroid cream. If this happens, see your doctor for further treatment.

Key points to remember

Scabies is spread by close physical contact and is common in school-age children.
If left untreated, it will usually spread to all members of a child's family.
The mites and their eggs may live on clothes or bed linen for 1-2 days.
5% permethrin cream is recommended and should be applied to all body surfaces from the neck down.
In extremely young infants, 6% precipitated sulphur is preferred.
Treatment should be repeated a second time, 1 week later.

For more information

Department of Dermatology RCH Tel: (03) 9345 5510
Kids Health Info factsheets

Individual information

Developed by the RCH Dept of Dermatology and Emergency Department. First published in April 2008. Last updated May 2008.