The incubation period for scabies is from 1 to 6 weeks, during which the parasites select and develop a “territory.” The immune system instantly reacts to their appearance and the emerging “waste”. The duration of the incubation period depends on the number of mites that have fallen on a person’s skin: the more there are, the faster the main symptom of scabies will appear - itching. The intensity and nature of skin rashes is not affected by the number of mites; the allergic reaction depends on the interaction of the human immune system and the waste products of the parasites. A sick person, constantly and vigorously scratching the bite sites, involuntarily introduces an infection, for example, staphylococcal; in this case, the bacteria “add” their own symptoms of the disease, giving the rash a pustular character.
When and where is it easiest to get scabies?
Scabies mites are inactive during daylight hours. The main peak of activity of the female tick, responsible for laying eggs, occurs in the evening and night. She lives only 4-6 weeks, but, under favorable conditions, during this time she can give birth to 50 million new individuals. The female mite digs a scabies burrow at the border of the stratum corneum and granular layer of the epidermis at a speed of 2-3 mm per 24 hours, and lays 2-4 eggs in one day. Female ticks make their way forward, males make their way wider; The saliva of males contains a large amount of proteolytic enzymes, and due to this, the keratin of the skin is dissolved, forming a nutrient, a lysate. Mites become active and crawl to the surface of the skin when the owner (person) falls asleep. Ticks use this time to fertilize a new female and develop new territories. The night speed of ticks moving along the surface of the skin reaches 25 mm/min.
Be sure to consult a doctor
The picture of scabies in children may be similar to the signs and manifestations of weeping eczema, which is not amenable to traditional methods of treatment. Secondary infection is often associated with scabies in young children. Scabies is diagnosed based on medical history, after examining the child’s body and those in constant contact with the child. Laboratory tests reveal scabies mites.
If you have symptoms of scabies, you should contact a dermatologist or dermatovenerologist immediately. If the research results do not confirm scabies, then you will be additionally examined by a neurologist or allergist. Such a phenomenon as persistent itching of the skin cannot be left without attention!
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Types of scabies
Typical scabies and its symptoms
- Itching
- Rashes are scattered or multiple, small reddish nodules merging into one line. After a while, they turn into bubbles that burst to form a crust. Crusts with purulent contents mean that when scratching a person acquired a bacterial infection.
- Winding scabies passages, which consist of segments 5-8 mm long (this is the distance that the female mite “travels” per day). They peel off over time and look like gray scratches ending in a transparent bubble in which you can see a dark dot - this is the body of the tick. Typical location of this form of scabies:
- fingers, more precisely, the lateral surfaces of the fingers and the distance between them,
- bends of the hands and elbows,
- mammary glands (especially nipple halos),
- lower abdomen, male genital organs, etc.
Complicated scabies (with pustules) and its symptoms
Specific additional symptoms: dermatitis or purulent skin lesions.
Scabies of clean people and its symptoms
With increased attention to hygiene and a healthy immune system, rashes are very rare, and itching intensifies only in the evening and at night.
Nodular scabies and its symptoms
A few round skin lumps with a diameter of 2-20 mm, which are very itchy. They are colored red or brown, and scabies are visible on their surface. As a rule, they affect the penis, scrotum and inguinal-scrotal folds, circumference of the anus, nipple halos, inner thighs and buttocks.
Norwegian scabies and its symptoms
A very rare form, it appears only in those patients who, for various reasons, do not itch (do not feel itching or there is no allergic reaction due to weakened immunity). The skin thickens and becomes rough, rashes affect almost the entire surface of the patient’s body, even the skin of the face, hair and nail plates. The most unpleasant and characteristic symptom of Norwegian scabies is the formation of thick (up to 3 cm thick) crusts of a dirty yellow color over the entire surface of the body, under which extensive weeping erosions are exposed.
Modern view of scabies therapy
Etiology
Scabies, or, based on the species name of the pathogen, Scabies, is caused by the scabies mite Sarcoptes scabiei. Such diseases in veterinary medicine are called sarcoptic mange , after the generic name of the pathogen. The pathological process that occurs in humans when scabies mites come from animals is by analogy called pseudosarcoptosis .
The scabies mite is a permanent (obligate) parasite, the characteristic feature of which is transmission only from person to person, and the type of its parasitism determines the features of the etiology, epidemiology and clinical picture of the disease, diagnostic tactics and treatment. Ticks spend most of their lives in the skin of the host and only during a short period of settlement they lead an ectoparasitic lifestyle on the surface of the skin. S. scabiei parasitizes the superficial layers of the skin, but in a complicated course it can also affect its deeper layers.
The life cycle of scabies is represented by two stages: reproductive and metamorphic. The reproductive stage of the mite is as follows: the eggs are laid by the female in the scabies duct, where the larvae then appear. Unlike other insects, scabies mite larvae begin to actively move already in the egg, gradually shedding their egg shell. When they come into contact with the skin, they penetrate the hair follicles, forming follicular papules. The metamorphic stage is determined by the appearance of larvae, which penetrate the skin through a passage and, after molting, turn into protonymphs, then into teleonymphs, which then, in turn, turning into adults, are located on the patient’s skin in papules and vesicles. Over the next two weeks, atypical scabies (scabies without burrows) develops, since it takes two weeks for the larva to develop into a mature female capable of making burrows. The itch itself can persist for up to one and a half months and serve as a source of infection.
Epidemiology
The lifespan of scabies at room temperature 22°C and 35% humidity is about 4 days. At a temperature of 60°C, ticks die within an hour, and at temperatures below 0°C - almost immediately. Only young females and larvae are the invasive stages of scabies mite development. The average survival time for female scabies mites is three days, and for larvae - two. It is at these stages that itching can move from the owner to another person and exist in the external environment for some time. Moreover, house dust, wooden surfaces, and natural fabrics are the most favorable habitats for S. scabiei outside the host. It should be noted that sulfur dioxide vapor kills scabies mites in 2-3 minutes, and mite eggs are more resistant to various acaricidal agents.
The incidence of scabies increases in the autumn-winter period, which is primarily due to a sharp increase in the fertility of the mite. This is confirmed by the fact that the specific abundance of young females that do not lay eggs in scabies burrows drops to zero in the autumn months. Infection in 95% occurs through direct transmission of a tick from a sick person (and in half of the cases through sexual contact) or indirectly (through objects used by the patient). The low frequency of cases of indirect infection is explained by the weak viability of the tick in the external environment, since the pathogen is more often transmitted through the common use of bedding: washcloths, toys, writing instruments. Infection can also occur in showers, baths, hotels, trains and other public places if the sanitary regime is violated.
Clinic
With scabies, when infected by females, the incubation period is practically absent. The invading female immediately begins to gnaw through the tunnel and lay eggs. When infected with larvae, the incubation period is about 2 weeks, which corresponds to the time of tick metamorphosis.
The main and first subjective symptom of the disease is itching, which gets worse in the evening. Its intensity most often increases as the duration of the disease increases, which in turn depends on the number of the parasite and the individual characteristics of the organism. The latter include sensitization of the body to the mite and its metabolic products (feces, oral secretions released when gnawing, secretions of the oviduct glands) and the state of the patient’s nervous system (the degree of irritation of the nerve endings by the parasite during movement). The number and distribution of scabies in the skin is not random and is determined by the rate of regeneration of the epidermis, the structure and thermal regime of the skin. Mostly scabies burrows are located in areas of the skin that have a low temperature, minimal or absent hair, and the maximum thickness of the stratum corneum of the epidermis (hands, wrists and feet). The last factor allows the larvae to hatch from all the eggs, and not be rejected along with the horny scales.
Rashes in infants often affect areas of the skin that are extremely rarely affected in adults: the face and head, soles and palms. Moreover, sometimes the symptoms of scabies on the face and head are “masked” by the clinical picture of acute weeping eczema, resistant to conventional therapy. In children in the first months of life, scabies at first can often give the impression of childhood urticaria, since there are a large number of scratches and blisters covered with bloody crusts on the skin of the face, back and buttocks. In children, scabies can be complicated by severe pyoderma and sepsis, even leading to the death of the patient. It should be noted that in schoolchildren, complications of scabies in the form of secondary pyoderma often mask the parasitic process under the clinical picture of acute eczema, pyoderma or prurigo. In elderly people, the clinical picture of the disease is represented by bloody crusts and scratching in the absence of vesicles and the presence of single scabies.
When scabies is complicated, secondary pyoderma occurs in the form of impetiginous elements. A complication of the disease is the formation of postscabiosis lymphoplasia as a reactive hyperplasia of lymphoid tissue.
There are separate forms of scabies: nodular (postscabiosis lymphoplasia of the skin), scabies in children, Norwegian scabies, pseudoscabies.
Diagnostics
Clinical criteria for the diagnosis of scabies are the presence of scabies, papules, vesicles, and serous crusts that appear in typical places in the area of interdigital folds of the hands, wrists, abdomen, genitals, mammary glands, buttocks, and thighs (Table 1).
The clinical picture of scabies can also be represented by erosions, hemorrhagic crusts, excoriations, and foci of an erythematous-infiltrative nature. Often there are erased forms of scabies, which lead to erroneous diagnosis and are often regarded as allergic dermatosis.
The diagnosis of scabies is made based on clinical manifestations, epidemiological data and laboratory results. There are known methods for extracting a tick with a needle, thin sections, layer-by-layer scraping, and alkaline skin preparation. Express diagnosis of scabies is carried out using a 40% aqueous solution of lactic acid. Less commonly, the diagnosis is made on the basis of a positive effect when treated ex juvantibus with one of the acaricidal drugs.
Treatment
- Treatment of patients identified in the same lesion should be carried out simultaneously to avoid reinvasion.
- In children under 3 years of age, anti-scab preparations are rubbed into the entire skin; in other patients, the exception is the face and scalp.
- Rubbing in the preparations is carried out only with your hands for better delivery of the scabicide into the passages.
- Treatment is carried out in the evening, which is associated with the daily rhythm of pathogen activity.
- Treatment of complications of scabies is carried out simultaneously with treatment of the main process.
- Persons who have been in contact with a person with scabies are given prophylaxis to avoid “ping-pong” infection. It consists of a single treatment with any anti-scabies drug.
- It is recommended to wash the patient before and after the course of treatment. If necessary, the drug can be washed off every morning, and its exposure on the skin should be at least 12 hours, including the night period.
- Change of underwear and bed linen is carried out at the end of the course of therapy.
- Post-scabiosis itching after full therapy is not an indication for an additional course of specific therapy.
- Persistent scabious lymphoplasia of the skin does not require additional specific therapy.
A fairly large number of medications and therapeutic regimens are currently used to treat scabies. The most commonly used medications are presented in Table 2.
However, before starting treatment, it is advisable to take a hot shower using a washcloth and soap to mechanically remove mites and sebaceous gland secretions from the skin and to loosen the stratum corneum of the epidermis, which improves the adhesion of antiscabiosis agents. However, in the presence of secondary pyoderma, water procedures are contraindicated.
Treatment according to the Demyanovich method is carried out with two solutions: No. 1 (60% sodium thiosulfate solution) and No. 2 (6% hydrochloric acid solution). In previous years, it was the most common method of treating scabies. The method is recommended for local forms of scabies; for widespread forms, it is advisable to combine it with subsequent three-day rubbing of sulfur ointment. This technique is based on the acaricidal effect of sulfur and sulfur dioxide, which are released during the interaction of hydrochloric acid and sodium hyposulfite. This method has its drawbacks. These include labor intensity, frequent drug-induced dermatitis and low efficiency when used in outpatient settings.
Benzyl benzoate, emulsion (10% for children, 20% for adults). To prepare the emulsion, 20 g of green toilet soap, laundry soap or shampoo are dissolved in 780-800 ml of warm boiled water and 200 mg of benzyl benzoate is added. The suspension is stored in a dark place at room temperature for no more than a week. The person performing the rubbing washes his hands with soap before starting the therapy. The emulsion is shaken and rubbed into the entire skin with your hands, with the exception of the scalp, face and neck. First, the drug is simultaneously rubbed into the skin of both hands, then into the right and left upper extremities, and then into the skin of the torso (chest - abdomen - back - buttocks - genitals) and lower extremities, including the soles and fingers. Over the course of two days, two consecutive rubbings are carried out for 10 minutes. with the same break to allow the skin to dry. After completion of the treatment, bed and underwear are changed. After each wash, hands are re-sanitised. On the third day, the patient washes and changes his underwear again.
For the treatment of children under 3 years of age, a 10% solution is used, which is prepared by diluting a 20% suspension with the same amount of water. The drug is lightly rubbed into the skin of the scalp and face with caution to avoid getting the composition into the eyes.
In complicated or widespread forms of scabies, when new elements appear on the skin during treatment, and the patient complains of ongoing itching in the evening and at night, it is advisable to extend the course of therapy to three days or prescribe a second two-day course of therapy three days after completion of the first.
Benzyl benzoate, which is part of the water-soap suspension, has both anti-scabiosis and anesthetic effects. In unfavorable epidemic conditions, its use is most appropriate. The disadvantages include the local irritant effect of the drug, which can cause subjective sensations and pain when applying the composition to the skin.
Currently, ointments containing sulfur or tar (Wilkinson ointment, 20-30% sulfur ointment) are rubbed in for 10 minutes. into the skin, with the exception of the face and scalp. Rubbing is carried out for five days in a row, preferably at night, especially vigorously applying ointments to the tick’s favorite localization areas (hands, wrists, elbows, stomach). Every other day after completing the course of therapy, the patient washes with soap, changing underwear, bed linen, and outerwear. In areas with delicate skin (genital organs, peripapillary area, inguinal-femoral and other folds), rub the ointment more carefully to avoid dermatitis. Sulfur, in addition to anti-scabies, also has a keratolytic effect, which provides better access of the drug to the pathogen. In the presence of secondary pyoderma, it is first necessary to stop these phenomena with antibiotics or antibacterial ointments. In cases of severe eczematization that accompanies the parasitic process, local antihistamines and corticosteroids are prescribed. Among the disadvantages of this method of treatment are: duration of therapy, unpleasant odor, frequent development of complications. These ointments are not prescribed to persons suffering from eczema and children.
Lindane lotion (1%) is highly effective and low cost, which is applied once to the entire surface of the skin and left for 6 hours, then washed off. In hot climates, the drug in powder form is especially convenient (15.0-20.0 g of powder is rubbed into the skin 2-3 times a day, every other day you take a shower and change your underwear). The drug is also used in the form of 1% cream, shampoo or 1-2% ointment. A single treatment of a person with an exposure of 12-24 hours is sufficient. for a complete cure. Due to some toxicity, its use is strictly prohibited in children (under 2 years), pregnant women, patients with multiple scratches, suffering from eczema, atopic dermatitis, because it can cause an exacerbation of the disease. Recently, in connection with its use, cases of lindane-resistant scabies have been described, when even repeated treatments with this drug do not lead to recovery of the patient.
Crotamion is used in the form of 10% cream, lotion or ointment. Rub after washing twice a day with a daily interval or four times with an interval of 12 hours. during the day. Daily treatments are required for five days, since the drug is characterized by a low level of scabicidal activity and, accordingly, the occurrence of cases of tick resistance to crotamion.
A solution of esdepalletrin and piperonyl butoxide is applied to the skin from the cervical region to the soles (first to the skin of the torso, then to the limbs) in the evening. The aerosol allows you to apply the solution to the entire surface of the skin and ensures the penetration of the active substances into the scabies. In 12 hours. the drug is thoroughly washed off. If necessary, it is possible to re-use the anti-scabiosis agent 10-12 days after the initial treatment. The effectiveness of this remedy is 80-91%, and even if cured, itching and other symptoms may persist for another 8-10 days. The drug is used in all age groups and has no contraindications. Before using it, it is necessary to cure the phenomena of secondary infection (impetigo) or eczematization.
Malathion in liquid form is applied to areas of the skin of a patient suffering from scabies. Malathion is used as a 0.5% lotion (1% shampoo is used for head lice). Skin treatment is carried out in the evening hours. All family members are involved in the treatment process. The drug is applied to the entire surface of the skin, except for the face and scalp. In 12 hours. After applying the drug, rinse it thoroughly. Repeated treatment is possible on the 8-10th day of treatment. Be sure to change bed and underwear. The drug is used with caution in patients suffering from bronchial asthma and children, preventing inhalation of vapors of an alcohol-containing base, and therefore the use of an aqueous lotion is more advisable.
Permethrin is an effective and safe drug for the treatment of scabies. After a single treatment at night, the percentage of cured patients is 89-98%. The drug is left for 8-12 hours. (at night), then wash it off and put on clean underwear. The treatment procedure is repeated on the 7th or 10th day of therapy. The drug has several advantages: good tolerability when used in conditions of high temperature and humidity; can be used for complications of scabies (allergic dermatitis, pyoderma, microbial eczema); It is acceptable to use it for the disinfection of underwear and bed linen and in the treatment of other parasitic diseases (pediculosis and phthiriasis).
Prevention of scabies involves active identification of the source of infection and persons in contact with the patient, with the aim of involving them in preventive treatment. It is necessary to establish the degree of contact (direct/indirect), identify and eliminate foci of scabies, carry out clinical observation of patients, and carry out ongoing disinfection at the source of infection.
Sanitary treatment of things, clothing and premises increases the effectiveness of therapy with acaricidal agents, since it prevents possible relapses of the disease.
Highly effective products such as permethrin, esdepalletrin and piperonyl butoxide in aerosol cans are used to treat items that cannot be boiled. These remedies are also highly effective in the treatment of various types of lice, scabies, and infection with random types of parasites (fleas, bedbugs).
The linen of patients to be boiled is washed, thoroughly ironed or ventilated in the air for five days, and in the cold for one day.
Control of cure is carried out three days after the end of treatment, and then every 10 days for one and a half months. The success of treatment is determined both by the drug itself and its concentration, the choice of which depends on the age of the patient, the presence of pregnancy, the degree of development of the process, the presence of complications and their severity. The correct use of drugs also plays an important role. You only need to rub in any product with your hands, preferably in the evening. This is due to the nocturnal activity of the pathogen and the fact that 6-8 hours. sleep is enough to kill the active stages of scabies mites.
Of course, scabies is an urgent problem of modern dermatology, but thanks to successful etiopathogenetic and epidemiological developments in recent years, accumulated clinical, diagnostic and therapeutic experience, solving this issue does not look like an insurmountable task for doctors of any profile.
V.S. NOVOSELOV, Associate Professor of the Department of Skin and Venereal Diseases of the MMA named after. THEM. Sechenov; A.V. NOVOSELOV, clinical resident of the Department of Skin and Venereal Diseases of the MMA named after. THEM. Sechenov
