Scabies: How It Spreads and How to Treat It

Intense itching that gets worse at night, spreading through a whole family one person at a time, is the classic pattern of scabies. It is common, it is not a sign of a dirty home, and it clears properly only when the whole household is treated together.

What causes scabies?

Scabies is an infestation of the skin by a microscopic mite called Sarcoptes scabiei. The mites burrow into the top layer of skin and lay eggs there. Most people with scabies carry only about 10 to 15 mites in total, which is why you cannot see them. The eggs hatch in 3 to 4 days and take 1 to 2 weeks to become adult mites. The itching and rash are an allergic reaction to the mites, which is why they take time to appear.

How does it spread?

Scabies spreads through close skin-to-skin contact, such as living in the same house as someone who has it, and also through sexual contact. The more mites a person is carrying, the more easily they pass it on. This is why scabies moves through families, hostels and crowded housing so easily, and why treating only the person who is itching almost never works.

What does it look and feel like?

• Severe itching, worse at night. This is the main symptom.
• A raised rash or spots. On darker skin these may look like dark marks rather than red.
• Thin, line-like burrows, often on the fingers, wrists, arms and legs.
• Bumps on the genitals or breasts.
• In babies and small children, a widespread rash covering much of the body.

Symptoms usually start 4 to 6 weeks after the mites arrive, and the NHS says the rash can take up to 8 weeks to appear. That long gap is why people spread it before they know they have it.

How is it treated?

Scabies is treated with a cream or lotion applied over the whole body, or in some cases a medicine taken by mouth. A pharmacist or doctor must supply it and tell you how to use it. Children under 2 should be seen by a doctor rather than treated on a pharmacist's advice.

Three rules decide whether the treatment works:

1. Everyone in the home is treated on the same day, even those with no symptoms. Sexual partners from the past 8 weeks should also be treated.
2. The treatment is repeated, usually 7 days later, to kill mites that hatched from eggs after the first round.
3. Bedding and clothes are dealt with on the first treatment day. Wash them at 60C or higher, or in hot water dried in direct sunlight or a hot dryer. Anything unwashable goes into a sealed plastic bag for at least 3 days, and WHO suggests up to a week.

Expect itching to continue for a few weeks after the mites are dead, and it may feel worse for the first 1 to 2 weeks. That does not mean the treatment failed.

Can you go to school or work?

Adults and children aged 5 and over can return to work or school once treatment has started, avoiding close contact for the first 24 hours. Younger children can go back to nursery 24 hours after the first treatment.

When to see a doctor

See a doctor if:

• Your child is under 2 years old.
• The skin looks infected: weeping sores, crusts, yellow scabs, or spreading redness and swelling. Scratched skin can develop a bacterial infection called impetigo.
• The itching is still there 2 to 4 weeks after finishing treatment.
• Anyone has thick, dry, scaly, crusted skin with little or no itching. This is crusted scabies, which can carry thousands or millions of mites, spreads very easily and can be life-threatening. It usually affects people with weakened immunity and needs specialist care.

Get help urgently if someone with infected skin develops a fever, spreading redness, or becomes drowsy or very unwell, because untreated skin infection can lead to abscesses, blood infection and kidney damage. WHO notes signs of acute kidney damage in up to 10% of such children in poorer settings. In an emergency, call Rescue 1122 where available, or go to the nearest hospital emergency department.