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Scabies

Scabies is an itchy rash caused by the human scabies mite. It is spread easily through close physical contact.

With the right treatment it can be cured easily.

  • About scabies
  • Symptoms
  • Complications
  • Diagnosis
  • Treatment
  • Help and support
  • Further information
  • Sources
  • Related topics

About scabies

Scabies is caused by a tiny mite less than half a millimetre long called Sarcoptes scabiei. The scabies mites burrow into your skin, usually on the hands, wrists, ankles and male genitalia, where they live and lay their eggs.

People with a scabies infestation have an average of about 12 mites living under their skin. The presence of the mites, their eggs and their faeces cause an allergic reaction resulting in an intense itch and a rash.

Scabies can occur at any age, but it's most common among children.

How is scabies spread?

Scabies is highly contagious and is easily spread by direct touch. In adults this is often through sexual partners. Rarely, it can be spread through contact with bedding or clothes if the infested person has just been in contact with them. The scabies mite cannot live long without a host.

How common is it?

In the UK, about one in 1,000 people go to see their GP about scabies every month.

Scabies is more common in cities, in the north of the UK, among children and women, and during winter.

The number of scabies outbreaks seems to rise in populations in a regular cycle every 20 years, although no one knows why this is.

Symptoms

The scabies rash develops between two and six weeks after infestation but it can happen after only a couple of days if you have previously been affected. Intense itching develops which is often worse at night or when the skin is hot, for instance, after a bath or shower.

As well as itching and redness, scabies often causes small nodules or bumps on the skin that may be filled with pus. A scabies rash can also trigger other skin conditions such as eczema (itchy and scaly skin) or psoriasis (scaly skin). You may notice small burrow marks near the site of a scabies rash. These can be difficult to see as they may be obscured by the rash and marks caused by scratching. They look like thin and scaly zigzagging lines, less than a centimetre long. They are most easily seen on hands or feet.

In adults, scabies most commonly occurs between and on fingers, on the wrist, feet, armpits, stomach, buttocks and genital areas. In women, scabies may occur around the nipples. In men, nodules on the testicles or penis are common.

In children, scabies is more likely to occur on the face, neck, scalp, palms and soles. Pus-filled nodules, especially on the palms and soles, are more common in children.

In young babies, scabies may cause widespread eczema, especially on the abdomen (tummy), chest and back. Pinkish-brown nodules may also develop.

If scabies isn't treated it won't go away, and may lead to other infections of the skin such as impetigo.

Complications

Sometimes a type of scabies called crusted or Norwegian scabies can develop. Crusts containing thousands of scabies mites form on the skin. Norwegian scabies isn't as itchy as normal scabies - it may not itch at all - but it is contagious and is often the cause of scabies outbreaks in institutions such as hospitals or care homes.

People who have a weakened immune system, such as those who have HIV infection or AIDS, or those who are taking drugs to suppress the immune system after a transplant, are more likely to develop Norwegian scabies. It is also more common in people with neurological conditions (which affect the central nervous system), and the elderly.

Diagnosis

If you develop an itchy rash, go and see your GP. Scabies is sometimes difficult to diagnose, because similar itchy rashes can be caused by other skin conditions. Your doctor is likely to look for burrow marks in your skin. He or she is may also ask you if you have come into contact with anyone else with scabies, or if anyone in your family has had itchy rashes as well.

Treatment

Scabies is treated with an insecticide cream or lotion, called a scabicide. This is available to buy over the counter at a pharmacy. Always read the patient information that comes with your medicine and if you have any questions, ask your pharmacist for advice.

Applying the scabicide correctly is very important or the treatment won't be effective. Apply it twice, leaving a week between each application. This is best done on cool dry skin. Don't apply it after a hot bath, as the heat will cause the lotion to be more deeply absorbed and to be effective it needs to stay on the surface of the skin. It needs to be applied over the entire body including face, scalp, genitalia, hands and feet, and under nails.

Carefully follow the instructions that come with the scabicide. The lotion needs to be washed off between eight and 24 hours afterwards depending on which one is used.

When you are treated for scabies, all close contacts, such as family members or people you live with also need to be treated at the same time, even if they don't have symptoms, to make sure that the infestation is eradicated and that you don't become re-infested.

After treatment, your skin will continue to feel itchy for two to three weeks. Your GP may give you anti-itch creams or antihistamine tablets to reduce the itching.

After treatment some people develop itchy brown nodules, as wide as 2cms, on the genitalia or armpits. These usually disappear after about three months but can sometimes last up to a year.

What to do with bed linen

You will also need to machine wash all bed clothes and linen at a hot temperature on the day you start treatment to make sure that any residual scabies mites are killed. If you can't machine wash an item of clothing, keep it sealed in a plastic bag for 72 hours to keep any mites contained until they die naturally.

Tumble drying clothes at high temperature for 10 to 30 minutes, dry cleaning or ironing will also kill off the mites if you cannot machine wash some clothes. You don't need to fumigate any living areas to get rid of scabies.

Help and support

Scabies can leave you with feelings of guilt and shame, but it isn't necessarily a reflection of poor hygiene, just that you came into contact with the mite.

After having scabies, or other types of insect infestations, some people may believe that they are still infested, imagining bites or itching - when there is no mite present. This can be a very powerful illusion, and is known medically as delusions of parasitosis. Talk to your GP for more advice if you think you are affected.

Further information

Health Protection Agency

Sources

  • The management of scabies and threadworms. Prescribing Nurse Bulletin. www.npc.co.uk
  • Scabies: diagnosis and treatment. BMJ 2005;331:619-622. www.bmj.com
  • Simon C, Everitt H, Kendrick T. Oxford handbook of general practice. Oxford University Press. 2nd ed. 2005: 674
  • Scabies. Clinical Knowledge Summaries. www.cks.library.nhs.uk, accessed 7 November 2007
  • Scabies. Health Protection Agency. www.hpa.org.uk

Related topics

  • Psoriasis
  • Impetigo