scabies

Scabies: Short overview

• Infection: over prolonged, intense physical contact (hug, intercourse), sleeping together, caring for the sick, close cohabitation, sharing towels or clothes, playing games together
• symptoms: small pustules / blisters, small, reddish-brown mite glands on warm parts of the body (between fingers and toes, inner margins, underarm area, around the nipple vestibule, penis shaft, anal region), intense itching, burning (at night increased) allergy-like rash.
• Treatment: externally applied insecticides (whole body treatment), tablets
• Forecast: usually very fast and reliable treatment success, but skin irritations can persist even longer. No immunity, repeated infections possible
• Reporting requirements: to the health authority if several people are involved in community facilities (if a connection is likely)
• Important: Simultaneous co-treatment of all contact persons of the patient required!

Where can you catch scabies?

Infectious diseases are contagious, so is scabies. “Contagion” or “infection” in connection with scabies is sometimes referred to as “infestation”, a term that describes a colonization of the body with parasites.

The transmission of the scabies is done by direct skin contact with diseased persons. So there is usually no (animal) intermediate host, as is the case with many other parasitic diseases. There must also be prolonged body contact to allow the mites to move from one host to the next. This is the case, for example, during intercourse, which is why scabies are also counted among the sexually transmitted diseases.

Typical transmission paths are also, for example:

• sleeping together in a bed
• Body care of toddlers by parents or the sick by caregivers
• Caresses and cuddling
• playing together

Contrary to popular belief, contaminated items play less of a role as an infection path. The mites lose their infectiousness within a few hours at room temperature. However, infection is possible, for example, through contaminated carpeting, shared bedding, clothing or towels. Even furniture or medical instruments with which the patient came into contact should always be cleaned.

Personal hygiene plays only a minor role

What according to recent studies, however far less important than expected, is the body hygiene. Thus, the risk of infection can hardly be reduced even with intensive personal hygiene. However, the body care plays a role in the strength of the expression of the scabies. Because the worse the body hygiene, the more mites frolic on the skin.

Short touches such as shaking hands are usually not enough to get infected with scabies. Nevertheless, the body contact with infected people without protective clothing should be avoided as far as possible.

Beware of the bark stains

A special feature is the Scabies norvegica dar. In this form of scabies affected suffer from a very dense mite infestation, mostly due to an immune deficiency. While in patients with normal scabies rarely more than 12 to 30 mite gullies are found at the same time, with the bark scraps several million active animals can be present.

The more mites, the higher the risk of infection. Any dandruff that a person with Scabies norvegica loses can be covered with several thousand mites. It is therefore all the more important to isolate patients and to wear protective clothing when dealing with them and in their environment.

Several weeks incubation period

In case of scabies, the incubation period may be several weeks: The typical scabies symptoms occur only two to five weeks after the first infection. With renewed contagions it comes already after few days to symptoms. Without therapy, the scabies are usually not completely cured, although cases of spontaneous healing are described.

Is there a duty to report scabies?

According to the Infection Protection Act, scabies are then reportable if they break out in community facilities. These include, for example:

• kindergartens
• Old people’s and children’s homes
• schools
• Refugee shelters, asylum seeker homes

The management of the facility must, as soon as it has knowledge of the presence of scabies, report them to the responsible health authority and also indicate the personal data of the patient (s). A basic obligation to report individual cases does not exist, however, in the case of two or more diseases with a suspected connection.

Scabies may not work in community facilities or have contact with those who are cared for.

Scabies: Symptoms

Although the symptoms of scabies are typical, they are often unrecognized and confused with allergies or other illnesses. This may also be due to the fact that scabies have become very rare in Germany.

One distinguishes between direct and indirect symptoms of scabies:

Direct scabies symptoms

The so-called Milbengänge: The parasites dig small tunnels in the upper skin layer, which can show as a maximum of two to three centimeters long, irregularly serpentine (“comma-shaped”) Milbengänge. When visible to the naked eye, they appear brownish-reddish.

Often, despite an infection, no passages can be detected with the naked eye. For example, if they are covered by other skin conditions, or the skin color is very dark.

The number of mites can vary depending on the stage of the disease. An otherwise healthy person will normally have no more than eleven to twelve miles, while in the skin of immunocompromised patients there may be tens of thousands or even millions (scabies crustosa).

Even with people with a healthy immune system, there may be a few hundred mites at times, which is usually the case three to four months after infection. After a short time, however, the number of mites goes down sharply.

Personal hygiene has only a minor influence on the number of mites. Badly well-groomed people may have some more mites in their skin.

Indirect scabies symptoms: The response of the human immune system to the itch mites is most of the trigger of the main symptoms. Itching is the classic scabby symptom, scratching has given the disease its name:

• severe itching (pruritus) and / or slight burning of the skin
• Blisters and pustules, possibly nodules. The blisters are filled with fluid or pus, but contain no mites. They can be single or in groups.
• Rashes (Exantheme)
• Crusts (after the bursting of the liquid-filled bubbles)

As with some other skin diseases, the itching of scabies at night in a warm bed is usually much stronger than during the day.

Where do the scabies symptoms show up?

The pregnant mite females drill passages into the skin to lay their eggs there. They prefer to find places where the skin is thin and particularly warm. These include:

• the areas between the fingers and toes (interdigital folds) as well as the inner foot edges
• the wrists
• the axillary regions
• the nipples and the navel
• the penile shaft and the area around the anus

The back is rarely affected, the head and neck are usually spared. In infants and toddlers, however, the mite infestation can also occur on the face, on the hairy head and on the soles of the feet and feet.

The typical scabies symptoms are seen mainly where the mites sit. But they can also go beyond that and in some cases even affect the entire body. The latter is especially true for rashes (Exantheme).

Special forms of scabies and their symptoms

The scabies can, depending on severity and type of symptoms, in certain special forms:

• Scabies in newborns and infants
• well-kept scabies
• nodose scabies
• bullous scabies
• Scabies norvegica (crustosa), also called bark scraps

In the context of some special forms of the disease, the mentioned scabies symptoms can vary or more can be added.

Well-groomed Scabies

For affected people who use intensive body care including the use of cosmetics, the skin lesions described are often only discreet, which can make the diagnosis more difficult. One speaks then of a well-kept Scabies.

Nodose and bullous scabies

The nodular scabies are characterized by the development of very itchy reddish-brownish nodules. These do not contain mites and sometimes persist for months after successful parasitic killing.

If there are many smaller and larger blisters (Vesiculae, Bullae) within the scabies, then there is talk of a bullish scabies. This form is increasingly found in children.

Scabies norvegica (Scabies crustosa)

The above-mentioned bark scabies (Scabies norvegica or S. crustosa) differs significantly from the normal variant of scabies due to the massive mite infestation. There is erythrodermia on the whole body as well as the formation of small and medium-sized scales (psoriasiform picture).

Thick layers of the cornea (hyperkeratosis) develop on the palms and feet. Fingers, backs of hands, wrists and elbows can be formed with bark that is up to 15 millimeters thick. Under these crusts (which, incidentally, are not caused by bursting blisters), the skin appears red and moist-shiny. The barks are usually limited to a specific area, but may also spread to the scalp, back, ears and soles.

It should be noted that the itching – the most typical of scabies symptoms – can often be completely absent.

Scabies: Treatment

The scabies treatment is quick, painless and uncomplicated – at least in most cases. However, in certain circumstances, the treatment of parasitic skin disease can be difficult, for example when several people are affected within a community facility. The state of the patient’s immune system also plays a role, and in some patient groups there are deviations in the treatment concept.

The main goal of scabies treatment is to kill off the parasites that cause the disease. There are various medicines available for this, all of which, with one exception, are applied directly to the skin:

permethrin: The insecticide is applied as a cream on the entire body surface and is considered the drug of choice. Only in exceptional cases does the doctor resort to alternatives.

allethrin: Used as a spray in combination with piperonyl butoxide, but only used if permethrin therapy is not possible because of complications.

benzyl benzoate: Although has a high activity against the mites, but is also used only in exceptional cases due to the relatively complicated application.

Ivermectin: It is also used as a worm remedy and, in contrast to the other medicines, the scabies treatment is taken in tablet form.

Until a few years ago, lindane was used even more frequently as an alternative to permethrin, but now largely dispensed with since this insecticide is quite toxic.

In developing countries, in addition to cost-effective benzyl benzoate, scabies treatment also increasingly uses sulfur-containing preparations. In Germany, these play because of the unpleasant odor when applying and the potential toxicity no longer matter.

According to studies, the most common drugs for treating scabies rarely cause side effects such as skin rashes, diarrhea and headaches.

Allethrin may cause serious respiratory complications in patients with pre-existing conditions of the bronchi and lungs and should therefore not be used in these individuals.

This is how scabies treatment works

The mentioned active ingredients 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:

at permethrin As a rule, a single application is sufficient, with the entire body surface to be treated with the cream. However, the mucous membranes and body orifices must be left out, since there are no mites present at these sites and the body there reacts much more sensitively to the active substance. The head and thus the facial skin are also not treated for these reasons. It is recommended the Permethrin cream apply in the evening and wash them off with soap the next morning (at the earliest after 8 hours).

If signs of active mite infestation, such as mite gullies or other typical skin lesions, are still (or again) seen two weeks after the initial treatment, the treatment must be repeated. Likewise, this may be necessary in people with weakened immune systems.

In otherwise healthy people without immunodeficiency, there is no risk of infection for others even after the first proper scabies treatment. Children and adults can go back to school or to work after the first eight to twelve hours of therapy.

at allethrin and benzyl benzoate the application scheme is comparable. However, in some cases, the active ingredient must be applied several times.

In the case ofivermectin, which is swallowed, the substance passes quasi “from the inside” to the mites. Invermectin is swallowed twice at intervals of eight days as a tablet.

General measures for scabies treatment

In addition to the actual therapy with the mentioned drugs, there are some measures that support the scabies treatment and prevent further infections:

• The treating and contact personnel should wear gloves, in the case of bark scabs (scabies crustosa) also protective gowns.
• Both patients and staff should have their nails cut and their areas brushed under fingernails.
• The topical anti-mite agents work better when 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 clothing should be worn.
• Close physical contact with patients 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, bed linen and other items that have had prolonged physical contact with the patient should be washed at a minimum temperature of 60 ° C.

If washing is not possible, it is sufficient to store the items at least four days dry and at room temperature (at least 20 ° C). (If stored cooler, the itch mites would retain their infectious ability for several weeks.)

Special cases of scabies treatment

Certain circumstances require a deviation from the usual scabies treatment, but the drugs used are usually the same.

Pregnant, breastfeeding and children:

During pregnancy, all available scabies medications are problematic. Therefore, they should only be used if absolutely necessary and 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 can not be ruled out. Breastfeeding women should use permethrin only under medical supervision and, as the active substance can pass into breast milk, take a few days’ breastfeeding pause. The dosage is reduced in these groups of patients so that less active ingredient enters the systemic circulation.

Newborns and infants under the age of three should also be treated with (reduced dose) permethrin only under strict medical supervision. The application scheme is similar to that in adults, where the head is also treated, with the exception of the areas around the mouth and eyes. In addition, the cream should not be applied if the child has just been bathed in fresh water, since the then increased skin circulation a critical amount of the active ingredient could be absorbed through the skin into the body.

As an alternative to permethra, crotamiton is particularly important in children; otherwise, this drug plays a minor role in scabies treatment. In pregnant women Crotamiton is given only with great caution. Previously, benzyl benzoate is usually tried here.

Allethrin and invermectin should not be used during pregnancy.

Initial damage to the skin:

The skin is a natural barrier that prevents or impedes the entry of external factors into the body. If the skin is damaged, for example, by rashes or after severe scratching, in addition to pathogens and externally applied drugs can easily enter the body. Increased absorption of the substances may lead to increased side effects.

For larger skin defects, it is therefore important to treat them first, for example with corticosteroids (cortisol), before applying the drugs for scabies treatment. If this is not possible, systemic therapy with ivermectin must be resorted to.

Scabies norvegica (S. crustosa):In this special form of scabies, there is an extreme mite infestation, mostly due to an immune deficiency. The number of mites can reach millions, and patients suffer from the formation of bark and thick scales on the skin. Therefore, it is recommended to use permethrin at least twice every 10 to 14 days and to supplement the therapy with the addition of ivermectin.

In advance, the thick bark layers should be softened with special substances (for example, urea-containing creams) so that the active ingredient can better penetrate the skin (keratolysis).

A full bath before the scabies treatment, preferably with oil, supports the detachment of dandruff

Superinfection: For the treatment of superinfections, ie in the case of infection with other pathogens (eg fungi or bacteria), certain antibiotics are used.

Scabies treatment in communal facilities

If there are scabies in community facilities such as nursing homes or hospitals, several patients are often affected, in unfavorable cases even endemic diseases occur (localized but indefinite occurrence of the disease). Scabies treatment is often difficult. It must be done according to 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 need to be isolated.
• All patients and persons who have had contact with infected persons must be treated simultaneously, even if no symptoms are visible.
• In case of an infected person, the scabies treatment must be repeated after one week.
• Bed and underwear of all residents / patients must be changed and cleaned.
• Personnel and relatives must wear protective clothing.

While so far in community facilities has been treated mainly with permethrin, the trend is now more for treatment with ivermectin. Observations have shown that a mass therapy of all patients and contact persons with the single intake of ivermectin has a good chance of success and the relapse rates are the lowest. In addition, the intake of ivermectin is much less expensive than the application of external drugs, which is why a scabies treatment with this drug can be carried out more easily.

What are the complications?

In addition to the above symptoms, scabies can cause additional complications. An example are so-called superinfections. This is called the additional infection with other pathogens in an already existing disease.

In the case of scabies, for example, various bacteria can more easily penetrate the skin and cause infections (impetignation), because the upper skin layers are damaged by the constant scratching. The bacteria, mostly streptococci or staphylococci, cause in unfavorable cases:

• An erysipelas, also known as cutaneous rash, appear within a sharply defined area of ​​the skin and are often associated with fever and chills.
• an inflammation of the lymphatic vessels (lymphangitis) and severe swelling of lymph nodes (lymphadenopathy).
• rheumatic fever, sometimes a certain form of nephritis (glomerulonephritis). These complications may occur several weeks after infection with group A streptococci, but are rare.

If bacteria get into the bloodstream, there is also the risk of blood poisoning.

Another possible complication of scabies is a skin rash (eczema) caused by anti-mite agents. The skin is reddened and usually cracked, which in this case is no longer a consequence of scabies, but caused by the drying effect of the anti-mite agents. The patients feel a slight burning sensation and itching.

Because certain nerve fibers are permanently activated by constant itching during the onset of the disease, sensitization and reprogramming of neurons in the spinal cord may occur. The nerves are now so to speak permanently irritated and report a persistent itching, although long ago no trigger is present.

After a few months at the latest, however, the last of the scabies symptoms should disappear with the itching.

This is how scabies develop

The itch mites reproduce on the 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). In these passages, the mites linger a few weeks, lay their eggs and excrete many droppings, which is also known as skybala. After a few days larvae hatch from the eggs, which become sexually mature after a further two weeks. Thus the cycle starts from the beginning.

The mites do not produce poison or attack the body directly in any other way. The dug holes in the skin do not cause any pain or itching. The symptoms occur only because the body’s immune system reacts to the mites and their waste products. It activates certain cells and messengers that cause swelling, redness and itching. The affected skin areas can become inflamed and the scratching additionally irritates the skin.

Because the first contact with the mites takes a few weeks until the body has produced the special “anti-mite” immune cells, the symptoms only appear after this period.

The immune system has a “scabby memory”. In case of renewed infections, it quickly “remembers” the parasites and can react within a few days.

risk factors

Within some groups scabies occur more frequently than in the normal population. To call are:

• Children, especially since they have a lot of body contact with each other and the child’s immune system is not yet as well trained as the adult.
• Old people, especially if they already have pre-existing conditions and are housed in homes. Even with them, the immune system is often weakened.
• People with reduced itching sensation, such as Down syndrome (trisomy 21) and diabetics.
• Dementia can also promote scabies.

In addition, there are still some diseases with which together scabies occurs relatively often. Basically, a weakened immune system is a risk factor. This affects for example:

• Patients under chemotherapy
• HIV-Positive
• Leukemia sufferers

Even whole-body therapy with cortisol may in unfavorable cases increase the risk of scabies.

Hygiene plays only a minor role.

Occurrence of dross

In some developing country regions, up to 30 percent of the population is infected with scabies. In Central Europe scabies are meanwhile rather rare, but it can also come here again and again to outbreaks, mainly in community institutions such as nursing homes, day care centers or hospitals. In unfavorable cases, even endemias develop here, ie chronic states, whereby infections occur again and again within the limited range. Problem cases of this kind is then difficult to get along with a lot of effort.

In total, 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: Scabbers, what is it?

Scabies is a skin disease that has plagued mankind since time immemorial. The term comes from “scratching” and thus already describes the problem: those affected experience a sheer unbearable itching and therefore have to constantly scratch.

Scabies is one of the parasitic diseases (parasitosis), is thus caused by microorganisms that need another organism to feed or reproduce.

The female itch mites reach a size of 0.3 to 0.5 millimeters and can thus 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 between four and six weeks old and lays from the second week of life up to four eggs daily.

Outside the host, so 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

The scabies are not always easy to recognize despite their mostly pronounced symptoms. The mite gullies, which can be up to an inch long and look like small commas, are often scratched or covered by other skin conditions. In darker skin types, they are generally difficult or impossible to see.

If there is a suspicion of scabies, it must be confirmed with the detection of mites or their larvae or mite products. There are various diagnostic options for this:

Often with one sharp spoon scrape off skin (Curettage) to examine them microscopically. Ideally, the doctor has previously opened a mite pathway. If he does not find one, he will at least select a skin area that shows many symptoms.

A possible alternative to curettage may be the supervision microscopy be. If a mite can be easily recognized, the examiner can look at it with a special microscope or a magnifying magnifying glass and possibly detect the mites directly.

Sensitive is the diagnosis with the Dermatoscope, Here is looking for a brownish triangular shape, the head and the breast shield or the front two legs of the female mite.

Another method is the tape test or Tesafilmabriss. For this purpose, the doctor places a transparent tape on the suspected infected body parts, pulls it off abruptly and then examines it under the microscope.

One of the oldest methods is the ink test (Burrow Ink Test). Where mite gullies are suspected, ink is dripped onto the skin and excess liquid is removed with an alcohol swab. In places where there are actually mite gullies, the ink penetrates and becomes an irregular black line. There are no scientifically sound statements about how specific or sensitive this method is.

Scabies: Disease course and prognosis

You do not have to go to the hospital for “normal” scabies. Only in case of severe encrustation due to a disease with Scabis crustosa or in the case of infants, toddlers or in humans, in which the immune system is suppressed (eg 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 by cream or medication.

However, the symptoms of itchiness, especially the itching, can still persist for several weeks. Especially when the affected person’s skin has been damaged by dehydration and intense scratching, the healing process often recedes.

Wiederholte Infektionen mit Krätze stellen besonders in Gemeinschaftseinrichtungen ein Problem dar. Die strenge Behandlung ist ein äußerst zeitaufwändiges Unterfangen, da sowohl alle Patienten als auch das enge Umfeld beziehungsweise sämtliche Kontaktpersonen mit einbezogen werden müssen.

Additional information:

Guideline:

• S1-Leitlinie “Diagnostik und Therapie der Skabies” der Deutschen Gesellschaft für Dermatologie und Venerologie (DDG) Arbeitsgemeinschaft Dermatologische Infektiologie (Stand: 2016)