scabies
Marian Grosser studied human medicine in Munich. In addition, the doctor, who was interested in many things, dared to make some exciting detours: studying philosophy and art history, working on the radio and, finally, also for a Netdoctor.
More about the experts All content is checked by medical journalists.Scabies is a contagious skin disease caused by mites. The infection usually happens through close skin contact with the sick. The parasites and their excretions trigger an allergic reaction with a rash and severe itching. However, scabies can be treated very effectively. Here you can read the most important information about the infection, symptoms and treatment of scabies.
ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. B86
Scabies: quick reference
- Contagion: through prolonged, intensive body contact (hugging, sexual intercourse), sleeping together, caring for sick people, living close together, sharing towels or clothing, playing together
- Symptoms: small pustules / vesicles, small, reddish-brown mite ducts on warm parts of the body (between fingers and toes, inner edges of the feet, armpit area, around the areola, penis shaft, anal region), severe itching, burning (increased at night), allergy-like rash.
- Treatment: externally applied insecticides (whole body treatment), tablets
- Prognosis: usually very quick and reliable treatment success, but skin irritations can persist even longer. No immunity, repeated infections possible
- Obligation to report: to the health department if several people are infected in communal facilities (if a connection is likely)
- Important: simultaneous treatment of all contact persons of the sick person is necessary!
Where can you get infected with scabies?
Infectious diseases are contagious, and that also applies to scabies. "Contagion" or "infection" are sometimes referred to as "infestation" in connection with scabies, a term that describes the colonization of the body with parasites.
Scabies are transmitted through direct skin contact with sick people. As a rule, there is no (animal) intermediate host, as is the case with many other parasitic diseases. For the transmission, there must also be longer physical contact so that the mites can migrate from one host to the next. This is the case, for example, during sexual intercourse, which is why scabies is also counted among the sexually transmitted diseases.
Typical transmission routes are also, for example:
- sleeping together in one bed
- Personal care of small children by the parents or of the sick by caregivers
- Caress and cuddle
- playing together
Contrary to popular belief, contaminated objects play less of a role as a route of infection. Because the mites lose their infectivity within a few hours at room temperature. Nevertheless, infection is possible, for example, via a contaminated carpet, shared bed linen, clothing or towels. Furniture or medical instruments that the patient has come into contact with should also always be cleaned.
Personal hygiene plays only a minor role
According to recent studies, however, what is far less important than expected is personal hygiene. In this way, the risk of infection can hardly be reduced, even with intensive personal hygiene. However, body care does play a role in the severity of the severity of the scabies. Because the worse the personal hygiene, the more mites cavort on the skin.
Short touches such as shaking hands are usually not enough to get infected with scabies. However, physical contact with infected people without protective clothing should be avoided entirely if possible.
Be careful with the bark scabies
Scabies norvegica is a specialty. With this form of scabies, those affected suffer from a very dense mite infestation, mostly due to an immunodeficiency. While patients with normal scabies rarely have more than 12 to 30 mite burrows at the same time, several million active animals can be present in bark scabies.
The more mites, the higher the risk of infection. Every flake of skin that a person with Scabies norvegica loses can be covered with several thousand mites. This makes it all the more important to isolate the sick and to wear protective clothing when dealing with them and in their surroundings.
Incubation period of several weeks
The incubation period for scabies can be several weeks: the typical symptoms of scabies do not appear until two to five weeks after the first infection. If you are infected again, symptoms will appear after just a few days. Without therapy, scabies usually cannot be completely cured, although cases of spontaneous healing have been described.
Do you have to report scabies?
According to the Infection Protection Act, scabies must be reported if it breaks out in community facilities. These include, for example:
- Kindergartens
- Homes for the elderly and children
- schools
- Refugee shelters, asylum seekers' homes
As soon as it becomes aware of the scabies infestation, the management of the facility must report it to the responsible health department and also provide the patient's personal data. There is no general obligation to report individual cases, but there is a general obligation to report two or more diseases with a suspected connection.
People suffering from scabies are not allowed to work in communal facilities or have contact with those cared for there.
Scabies: symptoms
The scabies symptoms are typical, but they are often not recognized and mistaken for allergies or other diseases. This can also be due to the fact that scabies has become very rare in Germany.
A distinction is made between direct and indirect symptoms of scabies:
Direct symptoms of scabies
The so-called mite ducts: The parasites dig small tunnels into the upper layer of the skin, which can appear as irregularly twisted ("comma-shaped") mite ducts a maximum of two to three centimeters long. When these are visible to the naked eye, they appear brownish-reddish.
Often, despite an infection, no passages can be seen with the naked eye. For example, if they are covered by other skin conditions or the skin color is very dark.
The number of mite ducts can vary depending on the stage of the disease. An otherwise healthy person normally has no more than eleven to twelve mite ducts, while several tens of thousands or even millions (scabies crustosa) can be present in the skin of immunocompromised patients.
Even people with a healthy immune system can sometimes have a few hundred mite ducts, usually around three to four months after infection. After a short time, however, the number of mite burrows drops sharply.
Personal hygiene has only a minor influence on the number of mites.People who are poorly cared for may have a few more mites on their skin.
Indirect Scabies Symptoms: The human immune system's response to the scabies mites is most of the main symptom triggers. Itching is the classic symptom of scabies, and scratching gave the disease its name:
- severe itching (pruritus) and / or slight burning of the skin
- Blisters and pustules, possibly also nodules. The vesicles are filled with fluid or pus, but do not contain mites. They can be present individually or in groups.
- Skin rashes (exanthema)
- Crusts (after the fluid-filled blisters burst)
As with some other skin diseases, the itching of scabies is usually much stronger at night in a warm bed than during the day.
Where do the scabies symptoms appear?
The pregnant female mites drill passages in the skin to lay their eggs there. They prefer to go to places where the skin is thin and particularly warm. These include:
- the areas between the fingers and toes (interdigital folds) and the inner edges of the foot
- the wrists
- the armpit regions
- the areolas and the navel
- the penile shaft and the area around the anus
The back is rarely affected, and the head and neck are usually spared. In babies and small children, on the other hand, the mite infestation can also appear on the face, on the hairy head and on the soles of the hands and feet.
The typical symptoms of scabies are mainly seen where the mites are located. But they can also go beyond that and in some cases even affect the entire body. The latter is especially true for the skin rashes (exanthema).
Special forms of scabies and their symptoms
Depending on the severity and type of symptoms, scabies can be divided into certain special forms:
- Scabies in newborns and infants
- well-groomed scabies
- nodular scabies
- bullous scabies
- Scabies norvegica (crustosa), also called bark scabies
In the context of some special forms of the disease, the mentioned scabies symptoms may vary or there may be more.
Well-groomed scabies
In those affected who practice intensive body care including the use of cosmetics, the skin changes described are often only very subtle, which can make diagnosis more difficult. One then speaks of a well-groomed scabies.
Nodular and bullous scabies
The nodular scabies is characterized by the development of strongly itchy reddish-brownish nodules. These do not contain mites and sometimes persist for months after the parasite has been successfully killed.
If a large number of smaller and larger blisters (vesicles, bullae) form in the context of scabies, then we speak of bullous scabies. This form is found more often in children.
Scabies norvegica (Scabies crustosa)
The above-mentioned scabies (Scabies norvegica or S. crustosa) differs significantly from the normal variant of scabies due to the massive mite infestation. The skin is reddened all over the body (erythroderma) and small and medium-sized scales form (psoriasiform picture).
Thick corneal layers (hyperkeratoses) develop on the palms of the hands and feet. Crusts up to 15 millimeters thick can form, preferably on the fingers, back of the hand, wrists and elbows. Under these crusts (which, by the way, do not come from burst vesicles) the skin appears red and shiny and moist. The bark is usually limited to a certain area, but can also spread towards the scalp, back, ears and soles of the feet.
It should be noted that here the itching - the most typical of the scabies symptoms - can often be completely absent.
Scabies: treatment
Scabies treatment is quick, painless and uncomplicated - at least in most cases. Under certain circumstances, however, the therapy of the parasitic skin disease can cause difficulties, for example if several people within a community facility are affected. The condition of the patient's immune system also plays a role, and there are deviations in the treatment concept for some patient groups.
The main goal of scabies treatment is to kill the parasites that are causing the disease. Various medications are available for this, all of which, with one exception, are applied directly to the skin:
Permethrin: The insecticide is applied as a cream to the entire surface of the body and is considered the first choice. The doctor only uses alternatives in exceptional cases.
Allethrin: Is used in combination with piperonyl butoxide as a spray, but due to possible complications it is only used when therapy with permethrin is not possible.
Benzyl benzoate: Although it is highly effective against mites, it is also only used in exceptional cases due to its relatively complex application.
Ivermectin: Also used as a worming agent and, unlike the other drugs used to treat scabies, it is taken in tablet form.
Until a few years ago, lindane was also used more frequently as an alternative to permethrin, but it is now largely avoided because this insecticide is quite toxic.
In developing countries, in addition to the inexpensive benzyl benzoate, sulfur-containing preparations are also increasingly used for scabies treatment. In Germany, these no longer play a role due to the unpleasant smell when applied and the possible toxicity.
Studies have shown that the drugs used to treat scabies very rarely cause side effects such as rashes, diarrhea and headaches.
Allethrin can cause serious respiratory complications in patients with pre-existing bronchial and pulmonary disease and should therefore not be used in such people.
This is how the scabies treatment works
The active ingredients mentioned are aimed directly at the mites. After application, permethrin, allethrin and benzyl benzoate diffuse into the skin, spread there and kill the parasites. The exact application varies depending on the drug:
In the case of permethrin, a single application is usually sufficient, whereby the entire surface of the body must be treated with the cream. However, the mucous membranes and body orifices must be spared, as there are no mites in these areas and the body reacts much more sensitively to the active ingredient there. The head and thus the skin of the face are also not treated for these reasons. It is recommended to apply the permethrin cream in the evening and wash it off with soap the next morning (after 8 hours at the earliest).
If signs of active mite infestation are still (or again) visible two weeks after the initial treatment, such as mite ducts or other typical skin changes, the treatment must be repeated. This can also be necessary for people with a weakened immune system.
In otherwise healthy people without immunodeficiency, there is no longer any risk of infection for others after the first proper scabies treatment. Children and adults can therefore go back to school or work after the first eight to twelve hours of therapy.
For allethrin and benzyl benzoate, the application scheme is comparable. However, in some cases the active ingredient has to be applied several times.
In the case of ivermectin, which is swallowed, the substance reaches the mites “from the inside”. Invermectin is swallowed as a tablet twice, eight days apart.
General measures for treating scabies
In addition to the actual therapy with the drugs mentioned, there are some measures that support the treatment of scabies and prevent further infections:
- The treating and contact staff should wear gloves and, in the case of scabies crustosa, protective gowns.
- Both patients and staff should have their nails trimmed and the areas under the fingernails brushed out.
- The topical anti-mite agents work better if they are applied about 60 minutes after a full bath.
- During the exposure time, the patient should wear cotton gloves and plastic gloves over them.
- After washing off the drug, completely fresh clothes should be put on.
- Close physical contact with the sick should be avoided.
- Intensive personal hygiene is important to prevent the mites from multiplying excessively.
In principle, all contact persons should be examined for symptoms of scabies and, if necessary, treated at the same time.
Clothing, bedclothes and other items with which the patient has had long physical contact should be washed at a temperature of at least 60 ° C.
If washing is not possible, it is sufficient to store the items in a dry place for at least four days and at room temperature (at least 20 ° C). (If stored in a cooler place, the itch mites would retain their infectivity for several weeks.)
Special cases in scabies treatment
Certain circumstances require a deviation from the usual scabies treatment, although the drugs used are mostly the same.
Pregnant women, breastfeeding women and children:
All available scabies drugs are problematic during pregnancy. They should therefore only be used if it is absolutely necessary and then only after the first trimester of pregnancy.
The standard drug permethrin should not be used in pregnant women or only with prior consultation with a doctor. Although there is no indication of harmful effects, side effects and damage to the embryo / fetus cannot be ruled out. Breastfeeding women should only use permethrin under medical supervision and, as the active ingredient can pass into breast milk, take a few days off breastfeeding. The dosage is reduced in these patient groups so that less active substance gets into the body's circulation.
Newborns and toddlers under three years of age should also only be treated with (a reduced dose) permethrin under strict medical supervision. The application scheme is the same as for adults, although the head is also treated here, with the exception of the areas around the mouth and eyes. The cream should also not be applied if the child has just been bathed, as the increased blood flow to the skin could result in a critical amount of the active ingredient being absorbed into the body through the skin.
As an alternative to permethirn, especially in children, crotamiton is an option; otherwise this active ingredient plays a subordinate role in the treatment of scabies. Crotamiton is given to pregnant women with great caution. Before doing this, you usually try benzyl benzoate.
Allethrin and invermectin must not be used at all during pregnancy.
Previous skin damage:
The skin represents a natural barrier that prevents external factors from penetrating the inside of the body, or makes it difficult. If the skin is damaged, for example by rashes or after severe scratching, not only pathogens but also topically applied drugs can enter the body more easily. The increased absorption of the substances can then lead to increased side effects.
In the case of larger skin defects, it is therefore important to treat them first, for example with corticosteroids (cortisol), before applying the drugs to treat scabies. If that is not possible, systemic therapy with ivermectin must be resorted to.
Scabies norvegica (S. crustosa): This special form of scabies leads to extreme mite infestation, mostly due to an immune deficiency. The number of mites here can run into the millions, and patients suffer from the formation of bark and thick cuticles on the skin. It is therefore recommended to use permethrin at least twice with an interval of ten to 14 days and to supplement the therapy with the addition of ivermectin.
In advance, the thick layers of bark should be softened with special substances (for example, urea-containing creams) so that the active ingredient can be better absorbed into the skin (keratolysis).
A full bath before the scabies treatment, ideally with oil, supports the shedding of the dandruff
Superinfections: Certain antibiotics are used to treat superinfections, i.e. in the event of infection with other pathogens (usually fungi or bacteria).
Scabies treatment in community facilities
When scabies infections occur in community facilities such as nursing homes or hospitals, several patients are often affected, and in unfavorable cases even endemics (localized but unlimited occurrence of the disease). The treatment for scabies is often difficult. It must follow strict guidelines in order to be successful in the long term:
- All residents or patients of the facility as well as staff, relatives and other contact persons must be examined for possible infections.
- Patients with scabies must be isolated.
- All patients and people who have had contact with infected people must be treated at the same time, even if no symptoms are visible.
- In infected people, the scabies treatment must be repeated after a week.
- Bed and underwear of all residents / patients must be changed and cleaned.
- Personnel and relatives must wear protective clothing.
While treatment with permethrin has hitherto been the main treatment in community facilities, the trend is now more towards treatment with ivermectin. Observations have shown that mass therapy of all patients and contact persons with a single dose of ivermectin has a good chance of success and the relapse rates are lowest. In addition, taking ivermectin is much less time-consuming than applying external medication, which is why it is easier to treat scabies with this active ingredient.
What are the complications?
In addition to the symptoms mentioned, additional complications can arise with scabies. One example are so-called superinfections. This is the name given to the additional infection with other pathogens in the case of an already existing disease.
In scabies, for example, various bacteria can more easily penetrate the skin and cause infections (impetignization) because the upper layers of the skin are damaged by the constant scratching. The bacteria, mostly streptococci or staphylococci, cause in unfavorable cases:
- an erysipelas: this inflammation of the skin, also known as sore rose, occurs within a sharply defined area of the skin and is often associated with fever and chills.
- inflammation of the lymph vessels (lymphangitis) and severe swelling of the lymph nodes (lymphadenopathy).
- rheumatic fever, sometimes a type of inflammation of the kidneys (glomerulonephritis). These complications can occur a few weeks after being infected with Group A strep, but are rare.
If bacteria get into the bloodstream, there is also a risk of blood poisoning.
Another possible complication of scabies is a skin rash (eczema) caused by anti-mite agents. The skin is reddened and mostly also cracked, which in this case is no longer a consequence of the scabies, but is caused by the drying effect of the anti-mite agents. Patients feel a slight burning sensation and itching.
Because certain nerve fibers are permanently activated by the constant itching while the disease is ongoing, there may be a sensitization and reprogramming of nerve cells in the spinal cord. The nerves are now permanently irritated, so to speak, and report persistent itching, although the trigger has long since ceased to exist.
After a few months at the latest, along with the itching, the last of the scabies symptoms should subside.
This is how scabies develop
The itch mites reproduce on human skin. After mating, the males die while the females use their powerful mouthparts to drill small tunnels into the outermost layer of skin (stratum corneum). The mites stay in these tunnels for a few weeks, lay their eggs and excrete many balls of feces, which are also known as skybala. After a few days, larvae hatch from the eggs and become sexually mature after a further two weeks. So the cycle starts all over again.
The mites neither produce poison nor do they directly attack the body in any other way. Even the dug passages in the skin do not in themselves cause pain or itching. The symptoms only occur because the body's immune system reacts to the mites and their waste products. This activates certain cells and messenger substances that cause swelling, redness and itching. The affected skin areas can become inflamed and scratching irritates the skin.
Mites cause scabies
Because it takes a few weeks for the body to produce the special "anti-mite" immune cells upon first contact with the mites, the symptoms only appear after this period.
The immune system has a "scabies memory".In the event of renewed infections, it quickly “remembers” the parasites and can react after just a few days.
Risk factors
Scabies occur more frequently within some groups than in the normal population. The following are to be mentioned:
- Children, because they have a lot of physical contact with each other and the child's immune system is not as well developed as the adult.
- Elderly people, especially if they already have previous illnesses and are housed in nursing homes. Their immune system is also often weakened.
- People with reduced perception of itching, such as Down syndrome (trisomy 21) and people with diabetes.
- Dementia can also promote scabies.
There are also a few other diseases with which scabies occurs relatively often. Basically, a weakened immune system is a risk factor. This affects, for example:
- Patients undergoing chemotherapy
- HIV positive
- Leukemia sufferers
Even full-body therapy with cortisol can, in unfavorable cases, increase the risk of scabies.
Hygiene plays only a minor role.
Occurrence of scabies
In some regions in developing countries, up to 30 percent of the population is infected with scabies. In Central Europe, however, scabies is now rather rare, but outbreaks can also occur here again and again, mainly in community facilities such as old people's homes, daycare centers or hospitals. In unfavorable cases, endemics, i.e. chronic conditions, develop here, with infections occurring again and again within the limited area. Problem cases of this kind are then difficult and costly to deal with.
Overall, the number of people infected with scabies is estimated at around 300 million worldwide, although there are no data for individual countries, as, for example, individual cases outside of community facilities do not have to be reported.
Description: Scabies, what is it?
Scabies is a skin disease that has plagued mankind for ages. The term comes from “scratching oneself” and already describes the problem: Those affected experience an almost unbearable itchiness and therefore have to scratch themselves constantly.
Scabies is one of the parasitic diseases, i.e. it is caused by microorganisms that need another organism in order to feed or reproduce.
The female itch mites reach a size of 0.3 to 0.5 millimeters and can therefore just be seen as a point with the naked eye. The males, on the other hand, are smaller and no longer visible. A female is around four to six weeks old and lays up to four eggs a day from the second week of life.
Outside the host, for example on furniture, the mites can survive a maximum of two days. In unfavorable conditions (warm temperatures, low humidity) they die after a few hours.
Scabies: examinations and diagnosis
Scabies is not always easy to recognize, despite its usually pronounced symptoms. The mite ducts, which can be up to an inch long and look like small commas, are often scratched or covered by other skin manifestations. They are generally difficult or impossible to see on darker skin types.
If there is a suspicion of scabies, this must be confirmed with evidence of mites or their larvae or mite products. There are various diagnostic options for this:
Often skin is scraped off with a sharp spoon (curettage) in order to examine it microscopically. Ideally, the doctor will open a mite duct beforehand. If he doesn't find one, he will at least choose an area of skin that is showing many symptoms.
A possible alternative to curettage can be overhead microscopy. With this method, if a mite burrow can be seen well, the examiner can look at it with a special microscope or a highly magnifying glass and possibly see the mites directly.
Diagnosis with a dermatoscope is more sensitive. Here the search is for a brownish triangular shape, the head and the breast shield or the two front legs of the female mite.
Another method is the adhesive tape test or scotch tape test. To do this, the doctor places a transparent adhesive tape firmly on the suspected affected parts of the body, pulls it off with a jerk and then examines it under the microscope.
One of the oldest methods is the Burrow Ink Test. Where mite ducts are suspected, ink is dripped onto the skin and excess fluid is removed with an alcohol swab. In places where there are actually mite ducts, the ink penetrates and becomes an irregular black line. However, there are no scientifically founded statements about how specific or sensitive this method is.
Scabies: disease course and prognosis
With "normal" scabies you don't have to go to the hospital. Only in the case of severe incrustations due to an illness with scabis crustosa or in the case of infants, toddlers or people in whom the immune system is suppressed (e.g. in AIDS patients), inpatient therapy in the hospital may be advisable.
Otherwise, however, with the right and consistent therapy, the mites can be killed within a few days using a cream or medication.
The symptoms of scabies, especially the itching, can persist for a few more weeks. The healing process often takes a long time, especially if the skin of the person concerned has suffered additional damage from dehydration and intensive scratching.
Repeated infections with scabies are a problem, especially in community facilities. The strict treatment is an extremely time-consuming undertaking, since all patients as well as the close environment or all contact persons have to be included.
Additional information:
Guideline:
- S1 guideline "Diagnostics and Therapy of Scabies" of the German Society for Dermatology and Venereology (DDG) Working Group Dermatological Infectiology (as of 2016)
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