know about scabies?

Scabies is an extremely itchy skin disorder that can be passed from one person to another. It is caused by an infestation with a parasite - the scabies mite. The mite lives on the skin and burrows into it. Scabies is spread to others through close skin-to-skin contact. It is easily treated with an insecticide lotion applied to the skin. Two applications of treatment are needed, one week apart.

What is scabies?

Scabies is caused by a mite (like a tiny insect) called Sarcoptes scabiei. The mite is a parasite, meaning it lives off the host (a human) with no benefit to the host.

Scabies mites are tiny. They have a cream-coloured body, bristles and spines on their back, and four pairs of legs. The female mite is bigger (about 0.4 mm x 0.3 mm) compared with the male (0.2 mm x 0.15 mm). With the naked eye you might be able to see them as a speck. The female mites tunnel into the skin and lay eggs. About 40-50 eggs are laid in the lifetime of a mite. The eggs hatch into larvae after 3-4 days; these then grow into adults within 10-15 days.

Most of the symptoms of scabies are due to your immune system's response to the mites, or to their saliva, their eggs or their poo (faeces). In other words, the rash and the itching are mostly caused by your body's allergic-like reaction to the mites, rather than the mites themselves.

The average number of mites on an infested person is 12.

How common is scabies?

Scabies is common. In the UK, about 1 in 1,000 people develop scabies each month. Scabies is more common in town (urban) areas, in women and children, in the winter, and in the North of the country. It is very common worldwide, particularly where there is poverty and overcrowding. There may be outbreaks in overcrowded places such as refugee camps.

How do you get scabies?

You need close skin-to-skin contact with an infected person to catch scabies. This is because the scabies mite cannot jump or fly.

Most cases of scabies are probably caught from prolonged hand-holding with an infected person. The hand is the most common site to be first affected.

Close skin-to-skin contact when having sex is another common way of catching scabies.

The skin-to-skin contact needs to be for a reasonable time to catch the mite. You usually need to be in skin contact for 15-20 minutes to catch scabies. Therefore, you are unlikely to catch scabies from an infected person by casual short contact such as a handshake or a hug. The more mites there are, the faster they can spread to another person.

The mites live in skin and can survive away from the host human for about 24-36 hours. You are unlikely to catch scabies from bedding and towels unless you use them immediately after being used by someone with scabies. However, just in case, it is best to treat bedding and towels by hot washing (described later).

Sometimes outbreaks of scabies occur in places such as nurseries and residential homes, where people are in regular close contact.

What are the symptoms of scabies?

·         Itching. This is the main symptom of scabies. This is often severe and tends to be in one place at first (often the hands), and then spreads to other areas. The itch is generally worse at night and after a hot bath. You can itch all over, even with only a few mites, and even in the areas where the mites are not present.

·         Mite tunnels (burrows). These may be seen on the skin as fine, dark, or silvery lines about 2-10 mm long. They most commonly occur in the loose skin between the fingers (the web spaces), the inner surface of the wrists, and the hands. However, they can occur on any part of the skin. You may not notice the burrows until a rash or itch develops.

·         Rash . The rash usually appears soon after the itch starts. It is typically a blotchy, lumpy red rash that can appear anywhere on the body. The rash is often most obvious on the inside of the thighs, parts of the tummy (abdomen) and buttocks, armpits, and around the nipples in women. The appearance of the rash is often typical. However, some people develop unusual rashes which may be confused with other skin conditions.

·         Scratching. Scratching due to intense itching can cause minor skin damage. In some cases the damaged skin becomes infected by other germs (bacteria). This is a secondary skin infection. If skin becomes infected with bacteria it becomes red, inflamed, hot, and tender.

·         Aggravation of pre-existing skin conditions. Scabies can worsen the symptoms of other skin conditions, particularly itchy skin problems such as eczema, or problems such as psoriasis. Scabies can be more difficult to diagnose in these situations too.

Note: the itch and rash of scabies are due to a reaction (allergy) to the mites (or their saliva, poo (faeces) or eggs). Scabies symptoms usually take 2-6 weeks to occur after you are first infected. The itch and rash can develop on any part of the skin, away from where the mites are actually burrowing. This means that you are infectious and can spread scabies before you even know you have scabies.

The picture above shows some typical mite tunnels (burrows) either side of the wrist skin crease. The picture below shows the typical rash that occurs as a reaction to the mites, in this case on the leg.