Scabies, referred to medically as Sarcoptes scabiei, is a contagious human skin infection caused by the itch mite. The mites are only 0.2 to 0.5 mm in size and therefore barely visible to the naked eye. The female mites burrow into the top layer of skin, where they lay their eggs over their lifetime of about four to eight weeks. The mite infestation only causes skin reactions after some time. Itch mites can spread especially where people live close together, which is why clustering of the infection occasionally occurs, especially in community or care facilities.
Itch mites spread between humans, especially during prolonged skin contact (generally five to ten minutes), for example while playing together, cuddling, helping with personal hygiene, sharing a bed or during sexual intercourse. Shaking hands or a brief hug usually does not lead to transmission. In the case of crusted scabies (scabies crustosa), a highly contagious form of scabies, the number of mites on the skin is very high, which is why even short-term skin contact may lead to an infection.
Without a host, the itch mites can survive for around two days in clothing or bed linen. But transmission through shared bed linen, blankets, upholstery or clothing is rare. However, it is possible in the case of crusted scabies because of the large number of itch mites.
The first symptoms of scabies often include skin burning and itching, which are made worse by the warmth of your bed. Itching may even affect areas of the skin that are not directly affected by itch mites. The spaces between fingers and toes, wrists, ankles, armpits, elbows, nipples and genitals are primarily affected. In infants and young children, the scalp, face and soles of feet may also be affected.
Typical symptoms include fine, irregular lines in the skin. These are the burrow tracks of the mites that are visible in the skin. After a while, the skin reacts by developing blisters the size of a pinhead, reddened raised nodules or pustules. In addition, areas of the skin injured by scratching because of the itching may develop purulent inflammation. In the case of a prolonged infestation, a large-scale allergic rash may develop in response to the mites‘ excretions.
In people who have an intensive body care regime, the skin changes and mite infestation can remain unnoticed for a long time due to the use of cosmetics. If left untreated, scabies often becomes chronic.
People with a weak immune system are at particular risk of developing the highly contagious form, crusted scabies. In these cases, a great number of mites are present in the skin, accompanied by pronounced encrustation.
Upon first infection, the symptoms become apparent after only two to five weeks, while they occur as soon as after one to four days on reinfection. Scabies is therefore contagious long before sufferers exhibit any symptoms and remains so while itch mites are present on the skin.
Scabies occurs worldwide and may affect people of any age. People who are infected by other sufferers are usually members of the family or those who share a household, as well as carers and nursing staff if people in need of care are affected.
Your local health authority can provide you with further advice and information. It has information on the latest situation and a wealth of experience in dealing with the infection
More (specialist) information is available online from the Robert Koch Institute (www.rki.de/skabies).
Further information on infection control can be found on the website of the Federal Centre for Health Education (www.infektionsschutz.de).