Scabies is a common parasitic skin disease caused by the scabies mite Sarcoptes scabiei. and is highly contagious. It is manifested by skin rashes on the abdomen and thighs, between which scabies passages are visible, severe itching and scratching of the skin. Vitropression, dermatoscopy, and scraping examination are performed to confirm the clinical diagnosis. Treatment requires benzyl benzoate treatment not only of the affected areas, but also of the entire skin. It is accompanied by a regular change of underwear and bed linen.
Scabies is a contagious parasitic disease, the causative agent of which is a scabies mite. The incidence is quite high. Despite the fact that scabies is considered a disease of antisocial personalities, people of all social strata are affected. In the last decade in the United States, the officially registered incidence rate ranges from 18 to 45 cases per 100 thousand population, but in fact it can be much higher. In children and young people, diseaseis registered more often because of their mobility and more active lifestyle.
Characteristics of the pathogen
Scabies is an anthropophilic parasitic disease, since the scabies mite parasitizes only on humans. The source of infection is a sick person, scabies is transmitted directly through contact or through infected household items. An adult has a size of about 100 microns and a powerful jaw apparatus for tunneling in the epidermis, tunnels are made by females, males mostly do not move, their main function is fertilization. In the population, the ratio of females to males is 2:1. Fertilization of the female takes place under the skin, after which the hatching larvae come to the surface for further penetration into the layers of the epidermis. Mating of scabies mites also occurs on the surface.
Thus, the tick comes to the surface twice during its life cycle. In order to get under the skin of a scabies mite, 15-20 minutes is enough, this explains the contagiousness. In the first half of the day, the female lays eggs, and at night she chews through the passages, the life cycle of the pathogen is from two weeks to two months, after which the tick dies and decomposes in the gnawed passages. The scabies tick is not resistant and at a temperature of + 55 degrees it dies in 10 minutes, and at a temperature of +80 it dies instantly. Outside of a person, the tick also dies quite quickly.
Mechanism of infection
Infection with scabies is possible in public places through door handles, stair railings, telephone handsets. As a result, an epidemic outbreak is created and a patient with scabies infects his environment of a domestic and professional nature. Infection with scabies can occur during sexual intercourse, infection of a man from an infected woman occurs more often. Scabies mite can be on animals for a short time, so infection with scabies from animals is not excluded, although it is extremely rare.
The causative agent of scabies is most active from September to December, it is at this time that the greatest number of outbreaks of scabies are diagnosed. Activity at night causes a high risk of infection within the family when one bed is used. The interdigital folds, wrist zones are primarily affected, and already with the development of scabies, the rest of the body is affected, except for the scalp and armpits.
The incubation period is from three days to two weeks, but with careful examination, you can notice the entry points of the scabies mite already in the first days after infection. After the females begin to actively lay eggs, the clinical manifestations of scabies increase. There is an unbearable itching, which increases in the evening and at night. Scabies passages in the form of linear inflamed areas are visible on the skin, the inflammatory reaction is also explained by the presence of chemically active substances in the saliva of the parasite, therefore allergic infiltration can be observed in the affected area. Due to severe itching, the skin is macerated, scratching is observed on the body, sometimes covered with bloody crusts. Clinical manifestations depend on the activity of the tick’s vital activity, on how much personal hygiene is observed and on the degree of allergization of the body to the pathogen.
With a typical form of scabies, rashes are localized on the abdomen in the umbilical zone, on the anterior inner surface of the thighs, on the buttocks, mammary glands, lateral surfaces of the fingers and feet, on the interdigital skin folds, in men, scabies can be localized on the skin of the scrotum and penis. Scabies look like a whitish or grayish straight or curved line from 5 to 7 mm, slightly rising above the skin. Only isolated rashes may appear on the face, on the skin of the palms and feet. Disease course is clearly visible under a magnifying glass, the end of the course with scabies ends with a small papule or vesicle. Papulovesicular elements are partially covered with spotty bloody crusts and reach up to 0.5 mm in size.
In addition to scabies, which have paired papulovesicles, there are spot and linear combs on the skin of a scabies patient due to severe itching. Depending on the severity of scabies, there may be foci of pyococcal infection, which are more often found in the extensor zones. There are purulent or bloody-purulent crusts on the elbows – a symptom of Ardi.
Scabies of the clean
Scabies of the clean is an erased form of the disease that occurs in people with normal immunoreactivity, as a result of which there is no allergic reaction to the presence of ticks. Increased attention to personal hygiene, when people take a shower several times a day and change their underwear and bed linen, also contribute to the erasure of clinical manifestations in scabies. It is characterized by single rashes on the chest and around the navel, which are practically not macerated and do not cause discomfort, itching is noted only at night. Hemorrhagic crusts may appear.
Nodular scabies occurs as a result of a delayed hyperergic reaction, which develops as a response to the products of the tick’s vital activity. The nodular form of scabies is usually a consequence of untreated or improperly treated scabies. The long course of the disease, reinvasion by the scabies mite contribute to the appearance of itchy reddish-brown nodules. The rash is lenticular in nature, nodules occur under the scabies and are located in places typical of rashes. This form is resistant to various anti-scabies therapy, since due to dense crusts, medicinal substances practically do not act on the tick.
The cortical (Norwegian) form is diagnosed in rare cases in patients who have sharply weakened immunoreactivity. Cortical scabies is the most highly contagious form, since the highest concentration of mites is noted in the crusts. Immunodeficiency conditions, common diseases in which there is a decrease in immunity and exhaustion, prolonged therapy with corticosteroids, cytostatics and alcoholism contribute to the development of cortical form.
Clinically, cortical form is characterized by the presence of grayish-dirty crusts that tend to overlap each other. The crusts are usually of different sizes and thicknesses, tightly soldered together and the underlying tissues, very painful when removed. After removing the crusts, yellow erosions are exposed.
The extensor surfaces, the back of the hands, elbows, knees, interdigital spaces, buttocks, abdomen, auricles, less often the face and scalp are affected. Thick hyperkeratosis develops on the palms and soles, which restricts freedom of movement. If the nail plates are affected, they deform, crumble, become thickened and change color.
The diagnosis is made by a dermatologist, therapist or infectious disease specialist based on clinical data and patient complaints. The presence of itching, which increases in the evening and at night, and the presence of characteristic linear combs, small papules and a positive symptom of Ardi make it possible to suspect the presence of scabies. When examining the contact persons, it turns out that most of them have the same clinical manifestations, there is information about the presence in the epidochage.
The study of scraping confirms the presence of this disease, but it should be borne in mind that many patients wash thoroughly before visiting the doctor, and therefore ticks may not be detected. In addition, with the formation of crusts or during a period of low activity of ticks, their concentration decreases, therefore, in the absence of ticks under microscopy, but in the presence of a characteristic clinical picture, scabies therapy is started.
In order to increase the motor activity of ticks, before taking the material, the skin is heated with warm glass or a little oil is dripped. The application of mascara and aniline dyes helps to color the itchy passages. In some cases, when it is not possible to detect the causative agents of scabies, the positive dynamics in the appointment of anti-infectious drugs is a therapeutic and diagnostic procedure. This diagnosis is called ex juvantibus.
In the treatment of scabies, regardless of the scheme, it is necessary to treat the entire skin, and not only the affected areas, with the exception of the scalp (except in cases when disease is localized on the scalp). Body washing and changing of underwear and bed linen should be performed only before and after treatment of scabies, during therapy body washing is prohibited.
Benzyl benzoate, produced in the form of emulsions, is the most common antiscabious drug, since it has low toxicity and high efficiency. Before use, it is necessary to wash the entire body, then treat the upper limbs, lower limbs and trunk with the exception of the scalp. The rubbing time should be at least two minutes for each area. Underwear and bed linen are changed with double ironing after washing. Two days later, a repeat course is conducted according to the same scheme. This achieves an effect on individuals who were in the larval phase. With complete relief of the epidemic focus and the absence of reinfection of a double course of Benzyl Benzoate is enough to cure scabies. After the end of treatment, furniture, clothes must be treated with an antiseptic solution or UV irradiation.
Aerosol preparations for the treatment of scabies are easier to use and their volume is sufficient to treat the patient and contact persons, There are aerosol preparations that can be used to treat children. They are sprayed 20-30 cm from the skin, leaving no free areas, after 12 hours, the body and epidochage are sanitized. One application is enough, but with complicated forms of scabies, it is recommended to repeat the procedure.
Lindane is a cream preparation that has no color and smell, when treating scabies, it is rubbed daily or twice a day into the skin. Before therapy and before each treatment with lindane, it is necessary to take a shower. This method of treatment is suitable for those who are used to taking a shower or bath every day. Lindane is also produced in the form of a powder for rubbing into the skin and in the form of shampoos. However, it is better for children and women during pregnancy and lactation to use a special gel.
Treatment of the cortical form has several features. Before antiscabious therapy, it is necessary to soften the crusts and remove them. Soap and soda baths and keratolytic ointments are usually used. After complete rejection of the crusts, treatment is carried out according to the usual scheme, the courses are repeated until complete cure. In addition, the correction of the underlying disease, which caused the weakening of the reactivity of the body, is carried out.
Prevention of scabies consists in the timely elimination of epidocages, the appointment of preventive therapy. Regular examination of children in preschool and educational institutions and personal hygiene significantly reduce, but do not exclude infection with scabies.