What is scabies?
Scabies is an extremely common and very itchy skin rash caused by a tiny mite (insect) called Sarcoptes scabiei. There are records of scabies affecting humans since ancient times (at least 494 BCE).
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What causes scabies?
The mites that cause scabies are tiny parasites (an organism – a parasite that lives on or inside another organism – the host) which are smaller than a pinhead. They are usually spread by direct skin-to-skin contact with someone who already has scabies and sometimes, but rarely, from shared clothing, towels or bedding. People affected by scabies have an average of about a dozen adult mites on/in their skin; a few may carry many more. Anyone can get scabies as it is very easily spread between people. It is not caused by being dirty or unhygienic.
Rarely, a variant of scabies known as ‘crusted scabies’ (previously called Norwegian scabies) can occur in people who have a poor immune system or who are elderly and ill due to other conditions. There are thousands of scabies mites on the skin in this variant and it is therefore highly contagious.
Scabies in animals is called ‘mange’. It is caused by a different type of mite and therefore cannot live on/in humans.
Is scabies hereditary?
No, but it is common for several members of a family to have scabies at the same time as it spreads easily when people live together.
What does scabies look like?
Itching is the main symptom of scabies, and it is often worse at night. It can take about a month from the beginning of the infestation for the symptoms to appear.
The itching can affect the whole body apart from the head and neck. The elderly and infants may develop a rash in these areas. It is common for several people in the same family and their friends to become itchy at roughly the same time.
A person affected by scabies will usually have a mixture of scratch marks and tiny red spots on their skin. Scratched areas may develop crusty sores which can become infected and develop into small pus-filled spots. A widespread rash similar to eczema is very common. The itchy rash can cover much of the body, but the mites are mainly found in the folds of skin: between fingers and toes, the palms of the hands, the wrists, ankles and soles of the feet, groins and breasts. The scabies mites burrow into the skin in these areas to lay their eggs, leaving tiny spots and silver-coloured lines, called burrows, on the skin. Adult mites are tiny, only about 0.4 mm long which, when looked at through a magnifying lens or dermatoscope, appear as a tiny dark dot at the end of a silver line.
How is the diagnosis of scabies made?
The clinician will usually be able to diagnose scabies based on the history provided and examination of the skin. You may have been in contact with someone who has been diagnosed with scabies and has the typical symptoms.
Can scabies be cured?
Yes, with the right treatment, it clears up quickly and completely; but if it is not treated, scabies can last for months or even years. Prompt treatment of all those affected, and any possible contact, is required to manage symptoms and prevent complications and spread.
How should scabies be treated?
The best way to treat scabies and avoid recurrence is to ensure that all family members, friends, and other close contacts (see below) are treated correctly at the same time, even if symptoms are not present.
Who should be considered a contact?
Who should be considered a ‘contact’? Scabies can spread easily through skin-to-skin contact with other people. Contacts will likely include all household members and sexual partners. It could also include any other skin contacts such as members of sports teams and individuals who do not live in an affected household but provide care, e.g. visiting family members, child minders and adult day care providers. Not all individuals with scabies have itch and rash. Asymptomatic people will re-infest their contacts if they are not treated concurrently. It is important to recognise that some will feel shame or guilt, which may have an impact on use of treatments, however, in reality, anyone can be infested by scabies. Informing and reassuring relevant contacts so that they can receive effective treatments is vital to stop the spread of scabies.
What treatments are available for scabies?
Several treatments are available including topical (applied to the skin) and oral (tablets).
Effective topical treatments include permethrin cream, malathion (spray) and benzoyl benzoate (currently licensed only in Ireland). The doctor may suggest different options for women who are pregnant or breast-feeding, and for babies. These can be prescribed, bought over the counter, or purchased from on-line pharmacies without a prescription.
Advice for application of topical treatments
The mites may be anywhere on the skin, so the treatment must be applied to ALL areas of the skin, and not just to the itchy parts.
Treatment is best applied at night – see below for tips on how to use:
- Remove all clothes.
- Wash before treatment with cool (not hot) water, ensuring the skin creases and areas under nails are cleaned thoroughly. It is best to cut nails short.
- Apply treatment to clean, cool and dry skin.
- Apply to ALL areas of the skin, including all of the body, neck, scalp and face (only avoiding areas around the eyes). The product advice may suggest not treating the scalp and face, but it is best that all these areas are treated.
- Certain areas of skin need particular attention for treatment to be successful – ensure the product is applied generously to:
-skin between fingers and toes
-ideally, remove all jewellery, or make sure to apply to the skin under jewellery
-apply the product to soles of feet last
-skin behind ears
-under fingernails and toenails (using a soft toothbrush can help with this).
- Once applied, leave 10-15 minutes for the product to dry before dressing.
Treatment should be left on the skin for at least 12 hours.
- Some people may benefit from a further application 12 hours later , this will ensure the medication is on their skin for 24 hours. If any skin is washed during this time (most likely to be the hands), the product should be reapplied.
- The product should be washed off without soap initially, i.e. just water. Once completely showered, soap and/or moisturisers or emollients can be used.
- Once treatment has been used you can return to all normal activities.
- Treatments should be repeated as above 7 days later to ensure both the scabies mite and the scabies eggs have been destroyed.
For certain forms of scabies, a tablet called Ivermectin can be prescribed.
In most cases, the mites will not survive for long on bed linen, towels and clothes. Normal washing of these is recommended at the same time as treatment. Any item that cannot be washed should be placed in sealed bags for 3 days.
When scabies has been caught from a sexual partner, a full sexually transmitted infection (STI) check is advised.
What should I do if my symptoms do not improve?
Even after the mites have been killed by treatment, the itching usually carries on for a few weeks before settling.
Scabies treatments applied to the skin can cause skin irritation: this can be one cause of an ongoing rash and itch. Moisturisers (emollients), topical corticosteroids (steroid creams or ointments) and antihistamine tablets may be used if needed.
A recurrence of scabies is, unfortunately, quite common, especially if not all contacts are treated at the same time. If scabies is ongoing or recurrent, then all cases and all relevant contacts will need further treatment.
If skin problems do not settle 6-8 weeks after treatment or if there are any ongoing concerns, then a review of the skin by a health worker should be arranged.