Scabies: infection, diagnosis, treatment

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Scabies (called scabies among experts) is an infection of the skin caused by parasites. A really unpleasant idea, which is only topped by reality. The triggering itch mites drill tunnels into the top layer of skin and lay their eggs there. They depend on us humans as hosts and can only survive on us. Scabies is highly contagious and brings a lot of uncomfortable symptoms with it.

Scabies have been around for ages. It owes its name to the persistent and severe itching and the associated scratching. The symptoms of scabies range from mild skin irritation to eczema-like inflammation of the skin. The infection occurs through direct skin contact. The infection rate is very high and can lead to endemics, i.e. localized but increased infections. Today, scabies can be treated quickly and easily and only represents a real danger in exceptional cases.

The scabies: mite ducts under the skin

Scabies is caused by scabies mites (grave mites). The typical rash, however, is not a direct product of the mites, but rather the human body’s immune response to their excretions. The female mites drill tunnels, the so-called mite ducts, under the top layer of skin. While the males die after mating, the females crawl into the tunnels and lay their eggs there. The mites are about 0.3-0.5mm in size and live on average 4-6 weeks. During this time they lay new eggs approximately every 4 days. Larvae grow in the eggs and hatch just a few days after being laid. A further 14 days later, these too have grown into mites and are sexually mature. The cycle starts all over again.

Infection with scabies

Close skin contact promotes infection

The parasite infection is transmitted through skin contact. The closer the contact with an infected person, the more likely it is to contract scabies. The only host is humans. The mites cannot survive on animals. In close skin contact, such as cuddling with the children or having sexual intercourse with a partner, the mites migrate from one person to the other. When the new host arrives, the mite ducts begin to form immediately.

Notice: Brief skin contact, such as shaking hands, almost never leads to transmission.

At room temperature, mites are no longer infectious.

Infection through shared textiles is low, but possible. It is therefore recommended to wash duvets, towels and clothes with hot water. At a room temperature of 20 ° or more, mites are no longer “infectious” after a few hours. Nevertheless, it can make sense to also clean the sofa and other upholstered furniture with a steam cleaner. In this case, simply vacuuming furniture is not enough.

Cleanliness has no effect on infection

The risk of infection can neither be positively nor negatively influenced by increased body and environmental hygiene. The scabies remains highly infectious and contagious. This is different, however, in the form of the scabies or the rash that follows. If you have scabies, hygiene, especially personal hygiene, plays a major role. The strength of the scabies and thus the number of mites on the skin can be minimized with thorough hygiene. The worse the hygienic conditions – be it in relation to personal hygiene or the environment – the more mites there are on the body.

A long incubation period is endemic

The incubation period for scabies is 2-5 weeks. This means that it takes a long time from infection to the first appearance of symptoms. Infected people are contagious at this time. Endemics, i.e. unlimited but localized infections, occur again and again in community facilities such as kindergartens, schools and shelters for the homeless.

In order to be able to localize such increased numbers of infections quickly and safely, doctors are obliged to report any scabies infection to the health department immediately. This reporting obligation already exists if a possible infection is suspected. The name of the person and possible locations in which an endemic could occur are reported. These include, in addition to the above, facilities for the elderly and the elderly, refugee accommodation and dormitories / residential groups.

Symptoms of scabies

The symptoms of scabies are often misinterpreted

The characteristic symptoms of scabies are inflammatory, dry, and scaly rashes. These rashes are associated with severe itching. Since scabies rarely occurred in Germany in the last few decades, the symptoms are often assigned to other diseases. This results in a large number of incorrect diagnoses. Allergies or skin diseases such as neurodermatitis are often incorrectly diagnosed at first.

When it comes to scabies, doctors today distinguish between two different symptom categories. They call these direct and indirect symptoms. One speaks of direct symptoms when these are caused by the mites themselves. It is mainly about the mite ducts that the females dig under the top layer of skin. The mite ducts are approx. 2-3 cm long and difficult to see with the naked eye. The number of mite ducts increases depending on the stage of the disease. The longer the scabies goes unnoticed or untreated, the more mite ducts there are. Usually there are at least 11-12 such passages under the skin. In the case of immunocompromised patients, this multiplies in the worst case to up to several thousand mite ducts.

The indirect symptoms of scabies

Doctors refer to all those that we would call typical scabies symptoms as indirect symptoms. They are not created directly by the mites, but are an immune defense in our body. The immune system reacts to the parasites and their excretions with endless itching, coupled with skin irritations and rashes. The rash may appear as blisters, pustules, or lumps that may be red and / or filled with pus. The skin burns and hurts. Rashes, red and rather scaly skin rashes, can also be the result of the parasitic infection. Most areas of the body that are warm and where the skin is quite thin are affected by mite ducts. These include the wrists, elbows, armpit region, the individual fingers, areolae and the genital area.

Toddlers and babies are also affected on the head

Since the skin of babies and small children is generally still quite thin, the mites can spread further and over a larger area. You can often find mite ducts on the head, neck and feet. The mites can also spread in children on the face, on the palms of the hands and on the inner thighs. The symptoms are always found where the mites can be found.

Special forms of scabies

• The well-groomed scabies
  It is a scabies infection that comes along with few or no symptoms. With the intensive use of cosmetics, creams and lotions, the skin reacts less often with rashes. The skin is literally used to perceiving foreign substances on the skin and therefore does not (or hardly) react to the parasites.
• The nodular and bullous scabies
  If there are very itchy nodules on the skin, the color of which is red-brownish, this is nodular scabies. There are no mites in the nodules, but the nodules often persist for months after successful treatment. Bullous scabies often appear in childhood and can be recognized by blisters of various sizes on the skin.

Diagnosis of scabies

The diagnostic options are diverse

In order to be able to diagnose scabies unequivocally, there are various options and tests. By simply examining the skin, mites can rarely be identified directly. This is often made more difficult by the large number of vacancies and scratches. Since the mites are only a few millimeters small, it takes a lot of luck and experience to spot them with the naked eye. However, no doctor will make a diagnosis of scabies simply by examining the skin.

Diagnostic procedure – the curettage

In this procedure, the doctor takes a skin sample so that it can be examined microscopically. A sample is scraped from the top layer of skin with a “sharp spoon”. Ideally, doctors try to identify a mite duct and open it with a spoon. A sample of the directly affected area naturally increases the chance of detecting mites.

Diagnostic method – the optical microscopy

If the mite ducts are clearly visible under the skin, an experienced doctor can use a highly magnifying glass. He tries to recognize active and living mites and their movements.

Diagnostic procedure – the adhesive tape test

The adhesive tape test is also used to actively search for mites. The doctor selects a severely affected area and sticks a transparent adhesive tape on the skin. This is pulled off with a jerk and then examined under the microscope. Even the smallest mites, as well as eggs and larvae, can then be discovered there.

Diagnostic procedure – the ink test

One test that was used for diagnostics many centuries ago is the ink test. Ink is dripped onto the skin where mite tunnels are suspected. Like water, ink also finds its way into the tiny tunnels. The ink runs down the corridors and spreads. In this way, the mite tunnels under the skin can be made visible.

Treatment of scabies

Consistent treatment achieves rapid results

The scabies is really extremely unpleasant, but with a consistently carried out treatment, it can be brought under control quickly. The situation is different in the case of a major outbreak in a community facility, such as a daycare center or in shelters for the homeless. There it often takes a long time until the last scabies infection is eradicated. The aim of treatment is always to kill all mites, eggs and larvae.

Medication and supportive good personal hygiene are important

Various medications are available for parasitic infections such as scabies. Most are applied to the skin in the form of creams and ointments. It is important that not only the affected areas, but the entire skin on the body is treated. Depending on the drug, the application takes place once or several times. Ivermectin is also an infection control drug. This is taken in tablet form and works from the inside out. All drugs should only be used in consultation with a doctor and on his recommendation. In addition to medication, good personal hygiene is essential.

Further measures to combat itch mites

It is recommended to cut the fingernails as short as possible during the treatment and to keep the nails clean at all times. This means that no other bacteria can get into the scratched wounds, nor can the mites settle underneath. Clothing and other textiles, such as towels and bed linen, must be completely changed after the treatment.

It makes sense to wash everything at at least 60 °. Textiles that cannot be washed must be dried for 4 days and separated at a room temperature of at least 20 °. This ensures that the mites that were there have died.

The course of scabies is usually harmless and without complications

The scabies usually shows no serious complications beyond the known symptoms. An otherwise healthy patient is cured after successful treatment and no longer needs any medical help. In immunocompromised patients, however, the scratched wounds can become so infected that in rare cases hospitalization is necessary. In these cases, the healing process takes a long time and requires close observation of the inflammation and wounds.

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