Sexually Transmitted Diseases - I. I. Mavrov 2005

Scabies

Scabies is an infectious parasitic Skin disease accompanied by nocturnal itching, excoriations, The formation of paired papulovesicles, and burrows.

Etiology. The CAUSATIVE AGENT OF scabies, Sarcoptes hominis, is a mite barely visible to the naked eye that parasitizes the stratum corneum of the skin. The body Structure OF THE mite is optimally adapted to its lifestyle. A soft yet extremely durable outer shell gives the parasite the degree of plasticity required for movement through the narrow channels of the stratum corneum (see plate XIII, 2).

The dimensions of the female average 0.375 mm in length and 0.270 mm in width. Externally, the male differs from the female by the presence of suckers on the two inner hind legs, smaller dimensions (0.15-0.25 mm), and a fork-shaped copulatory organ visible on the ventral side of the abdomen. The number of males is always much smaller than that of females. They chew very short passages, rather pockets, which they can leave at any time, or they are found in short lateral Branches of the burrows made by females.

The itch mite has 4 pairs of legs—two anterior and two posterior. Individual leg segments are capable of telescopic extension, and the first link can also partially retract into the mite's body. The burrowing of the mite occurs through the alternate extension and retraction of the legs, which in the extended state resemble drills. Oriented along the direction of movement, the legs mainly move laterally and clear space by displacing Tissues to the sides, while simultaneously the chisel-shaped HEAD shifts forward. Like the legs, the head is capable of retraction and bears two cylindrical formations as mandibles, which are evidently drilling Organs. Since the locomotive organs must be adapted for movement not only within the channel but also on the skin surface, the terminal segments of the front legs, along with setae and very small claws, feature cup-shaped suckers on stalks whose length equals that of the leg, and whose joints allow mobility in any direction.

In the burrows, the female lays eggs. Typically, a clutch contains 4 eggs. Since one egg is laid daily, the female remains in place for four days and only then continues her course, advancing 1 mm per day. Then she passes through the ventilation shaft again, lays eggs beneath it, and so on. The number of eggs laid by a fertilized female over her 6-8 week life cycle is usually about 50. Egg maturation takes 3-7 days. In artificial incubation in a moist chamber at 37 °C, larvae hatch after 50 hours. Young mites, whose females molt three times and males two, reach sexual maturity in approximately 7 weeks. There is, however, an opinion that the transformation of the mite into an adult takes place in 3 weeks.

At room Temperature, mites remain viable for 5-6 days, when kept in olive oil for 3 days, at sub-zero temperatures for 2 hours, and upon boiling, they die instantly. Lethal to the mite are sulfur preparations (sulfur dioxide), tar, petroleum and certain petroleum products (gasoline, kerosene), Aromatic Compounds (benzyl benzoate, Essential Oils), carbolic acid, soap, etc.

Routes of transmission. Infection occurs through direct contact, especially in a shared bed, and fairly frequent infection during sexual intercourse turns scabies into a sexually transmitted disease. Mites can also reach the skin of a healthy person through objects used by the patient (gloves, towels, toys, etc.). Minor epidemics flare up under conditions of close contact between children in nurseries, kindergartens, and schools. Usually, the mite does not leave the skin. Being isolated from it, it quickly dies. Therefore, its migration from bed to bed, for example in hospitals, never occurs. In this regard, isolation of scabies patients in hospitals is not required, except for cases of Norwegian scabies (a form of scabies with reduced bodily reactivity), in which mites in huge numbers, shedding along with scales and crusts, pose a risk of infecting doctors and attending staff.

Epidemiology. The incubation period is generally 7-10 days. However, it is often not limited to a specific time interval and fluctuates within very wide ranges, since the first symptom—itching—depends not only on the degree of infestation but also on the individual sensitivity of the infected person. In very rare cases is it possible to record the moment of infection, for example when a wife is infected by her husband returning from a trip. The estimated time of the onset of itching can vary completely—from a few days to several weeks. Yu. K. Skripkin and G. Ya. Sharapova (1972) believe that the duration of the incubation period for scabies is 10-30 days and depends on the number of sexually mature parasites that have reached the skin and are at various Selection/3.html">Stages of development.

In recent years, significant progress has been made in combating scabies. However, despite the overall decline in the number of patients, in A number of regions the incidence rate remains high, and in some areas, the incidence continues to rise.

The main reason for this situation in most regions is the inadequate and untimely sanitation of foci of infection—sources of infection and individuals who were in close contact with patients are not fully identified, prophylactic Treatment of contacts is not always carried out, diagnostic errors are often made, and in some cases, laboratory Methods for detecting the itch mite are not used (M. V. Yatsukha, 1991).

The general epidemiological characteristics of modern contact infections are largely inherent in itch mite infestation. The epidemiology of scabies also has its own features, both in each specific case and in foci (organized groups, recreation areas, business trips, hiking trips, etc.). To correctly understand the epidemiological situation and develop Sanitary and epidemiological measures, one should always delineate the classical Links of the epidemic process: sources, routes and mechanisms of parasite spread, and high-risk groups in whom The Development of scabies is most likely.

Sources of infection are primarily patients with scabies. A typical example of the high probability of epidemic outbreaks of scabies is organized groups (schools, boarding schools, kindergartens, nurseries, etc.). To a lesser extent, reservoirs of infection are objects used by a scabies patient (stationery, toys, sports equipment, etc.), as well as bathhouses, showers, hotels, and other places, provided that the established sanitary regime is not observed there.

When favorable conditions for infection are created (unsatisfactory Sanitary and hygienic conditions, crowding, frequent change of sexual partners, promiscuity in sexual contacts, etc.), a sharp increase in the number of scabies patients may occur, especially among certain population groups.

Clinical picture. Scabies is a disease whose manifestation depends on the skin's reaction to mite invasion. At the same time, the clinical picture varies among individuals, which is determined by a number of external factors. First among these is skin care, which determines the intensity of scabies manifestations. Neat people who wash frequently and thoroughly create such unfavorable living conditions for the mite that the development of a typical clinical picture of the disease does not occur at all.

Clinical manifestations of scabies often depend on the patient's occupation. It is known that the preferred Zones of the itch mite include areas of the skin subject to pressure. For example, in sedentary lifestyles (shoemakers, tailors, watchmakers, etc.), the sacro-gluteal zone is largely affected. In individuals working with substances lethal to the mite (painters, tanners, tinsmiths, masons, laundresses, etc.), typical manifestations of scabies on the hands are absent.

The Clinical presentation of scabies can be altered in the presence of other diseases in the patient (Syphilis, psoriasis, lichen planus, ichthyosis, etc.). In such cases, scabies affects the concomitant disease, the manifestations of which are superimposed on the Damage caused by excoriations. Ultimately, scabies itself recedes into the Background, and only clusters of rashes in the preferred localization sites of the mite, which are uncharacteristic of the concomitant diseases, make it possible to suspect the presence of scabies.

Scabies is characterized by seasonality. The disease is more common in the cold season.

Clinical signs of scabies are largely determined by itching and, accordingly, the excoriations provoked by it. These are precisely the main symptoms that the patient pays attention to first and which prompt them to consult a doctor.

Scabies is characterized by the fact that the itch becomes particularly pronounced at night in bed. Although this symptom is inherent in many pruritic dermatoses—which is explained by skin hyperemia under METABOLISM/18.html">The Influence of bed warmth—in scabies it is so strongly expressed also due to the increased nighttime activity of the mites. The intensity of itching varies and is not always adequate to the severity of clinical manifestations. In a number of cases, patients with very minor clinical signs complain of agonizing itching and vice versa. It seems that itching is more intense in the Cytology/cytology/16.html">Early stages of the disease, and less pronounced at later dates.

Preferred localization sites for mites are grooves from clothing compression, armpits, genitals, Mammary Glands, interdigital folds, wrists, navel, buttocks, and the extensor side of the elbow joint. Manifestations of scabies are generally observed on the anterior surface of the body, starting approximately from the level of the anterior axillary folds to the middle of the thighs (Fig. 48). The back is always free of lesions.

Mite burrows can also be found in other zones of The Human Body. Thus, in children, they are often observed on the face (in particular, in infants on the Cheeks or scalp due to infection through the mother's breast). Quite often in children, mite burrows are found on the inner edge of the FOOT. In exceptional cases, they are concentrated in the shoulder and genitoanal zones, on the mucous membrane of the Urethra (immediately behind the meatus), and even on the Cornea of the eye.

At the onset of the disease, pathological changes are not visible on the itchy skin, but then vesicles, papules, and other elements of the skin rash appear. Pronounced inflammatory phenomena in the form of redness form around the mite burrows, most often as small blisters ranging in size from a millet grain to a pea. Such blisters are in most cases found on the hands, and they extremely rarely remain intact. After excoriation, the reddish floor of the blister is often exposed, surrounded by the remains of a more or less dried membrane, which is initially shiny and then begins to peel. Rashes of this type are very frequently localized on the Penis.

Class="center">

Fig. 48. Scabies.

Subsequently, the content of the blister becomes turbid, forming pustules with a reddish halo, in the membrane of which the darkish mite burrows are clearly visible against the background of greenish pus. When the blisters and pustules dry in the area of the mammary glands, on the buttocks, thighs, abdomen, and fingers, crusts form.

Sometimes inflammation takes on a more plastic character. In such cases, an infiltrate develops, manifesting as a small nodule through which the mite burrows. When long burrows are present, elongated, ridge-like thickenings are formed. Occasionally, these appear on the extensor surface of the elbow joints, in the armpits, but most frequently—in cases of isolated mite burrows on the penis (see plate XIII, 1, 3).

In many instances, scabies is complicated by Pyoderma (impetigo, folliculitis, furuncles, abscesses), erysipelas, and eczema. The sequelae of scabies are most pronounced in typical sites of localization and in areas with particularly delicate skin, such as the extensor surfaces of the elbows and knees, the lateral surfaces of the fingers, the palmar regions, and the like.

Diagnosis. Identifying typical scabies is usually straightforward. The diagnosis is based on patient history, clinical presentation, and laboratory findings. A detailed medical history may include information on the onset of the disease, its nature, and the presence of pruritic skin conditions in family members and other contacts. Information regarding sexual contacts, recent travel, hotel stays, and similar details can help determine the time of infection and the duration of the disease.

Scabies manifestations in typical localization zones are usually so evident that they allow for a 'remote' diagnosis. Recognition is further facilitated if the patient reports similar symptoms in other family members, accompanied by nocturnal pruritus. To confirm the diagnosis, it is necessary to locate the mite burrows and the causative agent. In cases where burrows are difficult to identify, a useful technique involves applying methylene blue or an iodine solution to the skin areas—the mite burrow line stands out more clearly against the lightly stained background.

To detect mites and their eggs, it is advisable to excise the entire burrow by sliding a sharp scalpel underneath it, taking care not to go too deep, and lifting the burrow upward. Alternatively, one can target the mite eminence, successively removing the overlying epithelium with a horizontally directed needle until a tiny, slightly yellowish grain appears, which represents the female mite.

Mites, eggs, nymphs, and feces are most commonly detected by scraping scabies elements with a small ophthalmic curette until capillary bleeding appears (N. K. Solovyov, 1971). The scraping is placed on a Glass slide in a drop of a 20% alkali solution with glycerin (in equal proportions), covered with a coverslip, and examined under low magnification for about 10–20 minutes.

Differential diagnosis is performed to rule out strophulus, prurigo, and syphilis, and should also account for skin changes caused by animal scabies mites, bird mites, and similar agents.

Scabies treatment can be carried out using several methods, categorized as standard or accelerated. The former involves anti-scabies ointments (Wilkinson's ointment, 33% sulfur ointment). A single treatment course for one patient requires 200.0 g of ointment, which is vigorously massaged into the skin daily in 40.0 g amounts. The skin of the face, neck, and scalp must not be treated. Before applying the ointment, the patient must take a hygienic bath or shower. Following the initial application, the patient must put on clean underwear, which is changed on the 7th day of treatment after a bath or shower.

Complicated scabies requires a longer treatment course (12–15 days) due to the necessity of first resolving any secondary pyoderma or dermatitis.

Recurrence of the disease following thoroughly administered ointment therapy is exceptionally rare.

Accelerated methods (treatment with benzyl benzoate and the Demyanov method) allow patients to be cured in a shorter timeframe (2–3 days) and help avoid the undesirable transfer of ointments to bed linen and undergarments.

The Demyanov method involves the consecutive rubbing in of Solution No. 1 (60% sodium thiosulfate) and Solution No. 2 (6% aqueous Hydrochloric acid solution) over the course of one hour. Three days after bathing, the patient changes their undergarments and bed linen.

Benzyl benzoate emulsion (20 g of benzyl benzoate; 2 g of green or household soap; 78 ml of Water) is rubbed into the skin using a cotton-gauze swab twice for 10 minutes with a 10-minute interval between Applications (for 2 consecutive days). Three days after bathing, the patient changes their undergarments and bed linen.

Recently, new agents from the anti-scabietics group (such as scabicide) have been utilized for scabies treatment; these act successfully with short-term application, are odorless, and are capable of staining while remaining non-irritating to the skin.

Prophylaxis. Mandatory inpatient or outpatient treatment of infected individuals, tracing the source of the infection, and examining all household and sexual contacts.

Current and terminal disinfection of the infection focus, patient's clothing, and bed linen is carried out. Undergarments and bed linen used by the patient before and during treatment must be boiled and laundered. Mattresses, blankets, and other items are disinfected in a dry-heat chamber at a temperature of +100 °C for 1 hour. In winter, during sub-zero temperatures, these items can be left outdoors for 3–4 hours. Ironing with a hot iron is also effective. Special attention should be paid to hidden foci of scabies.