Scabies

 

What are the aims of this leaflet?

This leaflet has been written to help you understand more about scabies. It will tell you what it is, what causes it, what can be done about it, and where you can find out more about it.

What is scabies?

Scabies is a common and very itchy skin condition caused by human scabies mites. It can affect people of any age but is most common in the young and the elderly.

What causes scabies?

The mites that cause scabies are tiny parasites, smaller than a pinhead. They are usually picked up by direct skin-to-skin contact with someone who already has scabies, and only very rarely from objects such as clothing or bedding. Pets do not spread them. People with scabies have an average of about a dozen adult mites on their skin; a few carry many more. Being dirty does not cause scabies. Rarely, a variant of scabies called crusted scabies can occur in patients who are immunosuppressed or who are elderly and unwell. There are thousands of scabies mites on the skin in this variant and it is highly contagious.

Is scabies hereditary?

No, but it is common for several members of a family to have it at the same time.

What are the symptoms of scabies?

Itching is the main symptom of scabies, usually starting about a month after the mites were picked up. The itching affects the body and limbs but usually spares the head and neck, except in infants. The itch often gets worse in bed at night. It is common for several people in the same family, and their friends, to become itchy at roughly the same time.

What does scabies look like?

The rash of scabies is a mixture of scratch marks and red scaly areas; later it can become infected and develop small pus spots. A widespread rash similar to eczema (dermatitis) is very common. This itchy rash covers much of the skin but the mites are found mainly in the web spaces of the fingers and on the palms of the hands, the wrists, ankles and soles of the feet. The scabies mites burrow into the skin in these areas to lay their eggs. Burrows appear as small greyish lines on the skin. Adult mites are tiny, only about 0.4 mm long, appearing through a lens as a tiny dark dot lying at the end of a burrow. In crusted scabies the rash may mimic psoriasis and may not cause intense itching.

How is the diagnosis of scabies made?

Your doctor will usually be able to diagnose scabies on the basis of the story and on examination of the rash. Scrapings from a burrow can be looked at under the microscope for mites and their eggs.

Can scabies be cured?

If it is not treated, scabies lasts for months or even years; but with the right treatment, it clears up quickly and completely. Even after the mites have been killed by treatment the itching usually persists for a few weeks.

How should scabies be treated?

The treatment of scabies involves:

1. Getting rid of your own scabies.
2. Making sure that you and other contacts don’t catch it again. This means that all family members and sexual contacts must be treated too at the same time whether they are itchy or not.

Several preparations are effective in the treatment of scabies. Of these, permethrin and malathion are the ones used most commonly in the U.K. It is worth checking that the preparation you have been given is one specially designed for use in scabies, as both agents are available in several formulations, some of which are useful only for head lice. Your doctor may suggest different preparations for women who are pregnant or breast-feeding, or for babies.

Follow the instructions issued with your treatment in detail; they will be based on the following principles:

• The mites may be anywhere on the skin, so the treatment must be applied to all areas below the neck in adults (and also to the scalp in children), and not just to the itchy parts.
• The treatment should be left on for at least 12 hours before being washed off.
• When you wash your hands, apply the treatment to your hands again afterwards.
• Two treatments, one week apart, are necessary to kill mites that have hatched out from eggs after the first application.
• One normal wash of bedding and clothes will eradicate mites.
• Taking a bath before treatment is not necessary.

If scabies is resistant to treatment or if it is the crusted type, then an oral treatment called ivermectin may be prescribed, usually as two doses of tablets taken one week apart.

Finally, if you caught your scabies from a sexual partner, your doctor may want to check for the presence of other diseases that could have been picked up at the same time.

What can I do?

If you follow the instructions you are given, you will clear your scabies successfully. You should also make sure that all of your close contacts apply the treatment at the same time as you. Catching scabies again is, unfortunately, quite common.

Where can I find more information about scabies?

On the Internet:
http://www.aad.org/dermatology-a-to-z/diseases-and-treatments/q—t/scabies
www.medinfo.co.uk/conditions/scabies.html