Chicken pox (chicken pox)

Chickenpox (chicken pox) is an acute systemic disease, usually in children, caused by the varicella zoster virus (human herpesvirus type 3). The disease usually begins with mild general symptoms, followed by rapid skin rashes that quickly spread and manifest as a spot, papule, vesicle and crust. The diagnosis is clinical. Individuals at risk of complications receive post-exposure prophylaxis with immunoglobulin and, if the disease develops, are treated with antiviral drugs (valaciclovir, famciclovir, acyclovir). Vaccination is effective.

[1], [2], [3]

Epidemiology

The source of the virus is a patient from the last day of the incubation period to the 5th day after the appearance of the last rash. The main transmission path is airborne. The virus can spread over distances of up to 20 m (through corridors to neighboring apartment rooms and even from one floor to another). A vertical mechanism of transmission of the virus through the placenta is possible. The susceptibility to chickenpox is very high (at least 90%), except for children of the first 3 months of life, who have passive immunity.

The incidence is characterized by pronounced seasonality, reaching a maximum in the autumn-winter months. Mostly children are ill. Postinfectious immunity is strained, maintained by the persistence of the virus in the body. With a decrease in its intensity, herpes zoster develops.

[4], [5], [6], [7], [8], [9], [10], [11], [12]

Causes of the chickenpox

The cause of varicella is the varicella virus Varicella zoster virus of the Herpesviridae family. The size of the virus is from 150 to 200 nm, it is found in the wind-blown vesicles in the first 3-4 days of the disease; after the 7th day, the virus can not be detected. The genome has a double-helix linear DNA molecule, a lipid envelope. The virus is reproduced only in the nucleus of infected human cells. The identity of the virus that causes herpes zoster and the varicella zoster virus is established. In the environment, the virus is unstable and quickly dies, in droplets of mucus, saliva virus persists for no more than 10-15 minutes. Heating, sunlight, UV radiation quickly inactivate it.

The chickenpox is very contagious and spreads by airborne droplets, especially during the prodrome and during the early rash period. The infectious period is defined from 48 hours from the moment of the first rashes until the appearance of crusts. Direct transmission (from media) is not possible.

Epidemic outbreaks are possible in winter and early spring and have 3-4 cycles. Infants may have immunity, probably transplacental, up to 6 months.

[13], [14], [15], [16], [17], [18]

Pathogenesis

The entrance gate of the chickenpox virus is the mucous membranes of the upper respiratory tract, where the virus replicates, then the pathogen penetrates the bloodstream through the lymphatic channels. At the end of the incubation period, viremia develops. The virus is fixed in cells of ectoderm origin, mainly in the epithelial cells of the skin and mucous membranes of the respiratory tract, the oropharynx. Possible damage to the intervertebral ganglia, cerebellar cortex and large hemispheres, subcortical ganglia. In rare cases, the generalized form affects the liver, lungs, gastrointestinal tract. In the skin, the virus causes the formation of vesicles filled with serous contents, in which the virus is in high concentration. In severe generalized forms of the disease, vesicles and superficial erosions are found on the mucous membranes of the gastrointestinal tract, trachea, bladder and renal pelvis, urethra, conjunctiva: eye. In the liver, kidneys, lungs and the central nervous system, small foci of necrosis with hemorrhages along the periphery are revealed.

In pathogenesis, a significant role is assigned to cellular immunity, in the main system of T-lymphocytes, in the suppression of which a more severe course of the disease is observed. After the acute symptoms of primary infection abate, the virus persists for life in the spinal nerve ganglia.

[19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29]

Symptoms of the chickenpox

The incubation period of chickenpox lasts from 10 to 21 days, with the introduction of a normal human immunoglobulin can extend to 28 days.

The prodromal symptoms of chickenpox are often absent, rarely a short-term subfebrile condition is observed on the background of a deterioration in overall well-being. Vesicles usually appear simultaneously with a rise in temperature or a few hours later. With abundant exanthema, the temperature can rise to 39 C or higher. Rashes appear in waves for 2-4 days and are accompanied by a rise in temperature. The rash is localized on the face, scalp, trunk and extremities.

On the palms and soles, it is found only with abundant rashes. Elements of the rash initially have the form of small makulo-papules, which within a few hours turn into vesicles of round or oval shape, and size 2-5 mm. They are superficially located on a non-infiltrated base, their wall is tense, shiny, the contents are transparent, but in some vesicles it becomes turbid. Most vesicles are surrounded by a narrow border of hyperemia. Vesicles dry out after 2-3 days. In their place are formed crusts, which fall off after 2-3 weeks. After falling off the scabs, as a rule, there is no scarring. Eruptions are observed on the conjunctiva, the mucous membranes of the oropharynx, sometimes the larynx, genital organs. Vesicles on mucous membranes quickly turn into erosion with a yellowish-gray bottom, which after a few days are epithelialized. Rashes on the mucous membrane of the larynx and trachea, accompanied by swelling of the mucosa, can cause a rough cough, hoarseness, in rare cases, the phenomenon of croup. Rashes on the mucosa of the labia pions present a threat to the development of vulvovaginitis. Rashes are often accompanied by an increase in lymph nodes.

By the end of the first week of the illness, the temperature is normalized along with the drying out of the vesicles, and the patient feels better. At this time, many patients are concerned about skin itching.

In the hemogram during the rash, small leukopenia and relative lymphocytosis are observed. ESR is usually not increased.

In immunocompetent children, chicken pox rarely runs hard. In adults and immunocompromised children, the infection can be severe. Moderate headache, low fever and malaise can be expressed 11-15 days after infection and last about 24-36 hours after the onset of rashes. These problems are most likely in patients over the age of 10 years and are especially severe in adults.

[30], [31]

Forms

There are the following clinical forms of chicken pox:

With the flow:

• typical;
• atypical:
  • rudimentary;
  • hemorrhagic;
  • gangrenous;
  • generalized.

By gravity:

• lungs;
• middle-aged;
• heavy:
• with pronounced general intoxication;
• with pronounced changes on the skin.

A typical and atypical chickenpox (chicken pox) is allocated. Typical cases include cases with a characteristic rash. Most often the typical chickenpox flows in a light and medium-heavy form. Severe form of the disease occurs rarely, often in weakened children and adults, it is characterized by a prolonged remitting fever up to 6-8 days. There are such symptoms of chickenpox as: headache, possible vomiting, meningeal syndrome, impaired consciousness, arterial hypotension, convulsions. The rash is plentiful, large, its metamorphosis is slowed down, elements with an umbilical impression in the center, reminiscent of rash elements with a smallpox are possible.

Atypical forms include rudimentary, bullous, hemorrhagic, gangrenous and generalized varicella.

The rudimentary form is more often observed in children receiving immunoglobulins, plasma during the incubation period. The rash is ungrowth, rosely-papular with single very small vesicles. The general condition is not violated.

Hemorrhagic form of chickenpox is very rare in severely weakened patients suffering from hemablastosis or hemorrhagic diathesis, against the background of taking glucocorticoids and cytostatics. On the 2-3 rd day of rash, the contents of the vesicles become hemorrhagic. There are hemorrhages in the skin and mucous membranes, nosebleeds and other manifestations of hemorrhagic syndrome. A lethal outcome is possible.

Very rarely there is a gangrenous form of chicken pox. It develops in depleted patients, with poor care, creating the possibility of a secondary infection. Initially, individual vesicles take a hemorrhagic character, then surrounded by a significant inflammatory reaction. Subsequently, a hemorrhagic scab is formed, after falling off, deep ulcers with a dirty bottom and steep or dented edges are exposed. Ulcers, due to progressive gangrenous tissue disintegration, increase, merge, taking significant dimensions. Often there are complications of purulent-septic nature. The general condition of the patient is severe, the course of the disease is long.

Generalized (visceral) form. It occurs mainly in newborns, sometimes in adults with immunodeficiency. Hyperthermia, intoxication, and damage to internal organs are characteristic. Mortality is high. At the autopsy, small foci of necrosis are found in the liver, lungs, pancreas, adrenal glands, thymus, spleen, bone marrow.

Chickenpox poses a risk to the fetus and the newborn. If a woman has a disease at the end of pregnancy, premature births and stillbirths are possible. When a disease of chicken pox in the early stages of pregnancy, intrauterine infection of the fetus may occur with the development of various developmental defects in it. The probability of illness of newborns is 17%, their death rate is 30%. Congenital Chickenpox (chicken pox) is severe. Accompanied by severe visceral lesions.

[32], [33], [34]

Complications and consequences

A secondary bacterial infection (streptococci and staphylococcus) can be attached, causing cellulite and rarely streptococcal toxic shock. The most common complication of chickenpox (chicken pox) is a bacterial superinfection caused by Streptococcus pyogenes and Staphylococcus aureus. In this case, the contents of the vesicles are suppressed, forming pustules. Perhaps the development of impetigo or bullous pyoderma.

Pneumonia can complicate severe chicken pox in adults, newborns and immunocompromised individuals of any age, but not in young children with sufficient immunocompetence. Cases of "chickenpox" (viral) pneumonia that develops in the first 3-4 days of illness are described. Patients complain of shortness of breath, chest pain when breathing, cough with bloody sputum, high fever. Objectively noted cyanosis of the skin, signs of bronchitis, bronchiolitis, and in some cases can develop pulmonary edema. The pathological picture in the lungs may resemble miliary tuberculosis (since in the lungs multiple multiple nodules are detected). Of the specific complications, the most serious lesions are the lesions of the nervous system of different localization - encephalitis, meningoencephalitis, opticemia and myelitis, polyradiculoneuritis, serous meningitis. The most characteristic is wind-encephalitis, which accounts for about 90% of neurological complications.

There may occur myocarditis, transient arthritis and hepatitis, hemorrhagic complications.

Encephalopathy occurs in less than 1 case per 1000 patients, usually with resolution of the disease or within the first two weeks. Most often these symptoms of chickenpox (chicken pox) are resolved, although it can rarely last for long or lead to death. One of the most frequent neurological complications is acute post-infection cerebellar ataxia. Transverse myelitis, paralysis of the cranial nerves, manifestations similar to multiple sclerosis, can also occur. A rare but very severe condition in children may be Reye's syndrome, which begins on the 3rd-8th day after the onset of the rash, taking aspirin increases the risk. In adults in 1-2 cases per 1000 patients, there is encephalitis, which can endanger life.

The frequency of encephalitis development does not depend on the severity of the course of the disease. Most complications occur on the 5th-8th days of the disease. The cases of encephalitis development during the rash and even before the appearance of the rash are described. It is noted that the earlier encephalitis begins, the harder it goes. Encephalitis manifests acutely with impaired consciousness, convulsions only in 15-20% of patients. In other cases, focal symptomatology dominates, which increases for several days. The most characteristic are cerebellar and vestibular disorders. Mark ataxia, tremor of the head, nystagmus, chanted speech, intentional tremor, discoordination. Possible pyramidal signs, hemiparesis, paresis of cranial nerves. Rarely observed spinal symptoms. In particular, pelvic disorders. Meningeal syndrome is weak or absent. A part of patients in the cerebrospinal fluid exhibit lymphocytic pleocytosis, an increase in the amount of protein and glucose. The course of the disease is benign as neurocytes suffer rarely, only with the development of encephalitis in early periods. Unfavorable long-term consequences are rare.

[35], [36], [37], [38], [39], [40]

Diagnostics of the chickenpox

The diagnosis of varicella in normal cases is not difficult. Diagnosis is established, mainly, on the basis of clinical data, while taking into account the epidemiological history. Varicella (chicken pox) should be suspected in patients with a characteristic rash. It should be remembered that a similar rash occurs in other patients, with viral skin lesions.

If necessary and in diagnostically vague cases, use virososcopic, virological, serological and molecular biological methods. Virousoscopic diagnostics of chickenpox consists in staining the contents of the vesicle with silvering (according to MA Morozov) for the detection of the virus with the help of a conventional light microscope. Virological method is practically not used. From serological methods apply RSK, RIMF, ELISA. The main method of laboratory diagnosis is the molecular biological method (PCR).

[41], [42], [43], [44], [45], [46]

Differential diagnosis

Differential diagnosis of chickenpox is carried out with a herpetic rash with simple herpes, herpes zoster, vesicle rickettsiosis, impetigo and smallpox. It is necessary to exclude herpes Kaposi's eczema, as well as infections caused by Coxsackie and ECHO viruses.

Beginning with short-term malaise, weakness, subfebrile body temperature, perspiration in the throat for 2 days

THERE IS

The study continues

The appearance of rash on the I-3rd day of the disease on the face, the scalp with spread to the trunk and limbs, mucous membranes. Simultaneous deterioration of health, increased body temperature, the appearance of symptoms of intoxication (headache, weakness, vomiting)

THERE IS

The study continues

Polymorphic character of the rash. In one area of the skin, you can see a spot, papules, vesicles, pustules, crusts (false polymorphism of the rash)

THERE IS

The study continues

In an anamnesis, contact with a sick chickenpox 2 weeks before illness

THERE IS

A clinical diagnosis is made: "Chicken pox, medium-heavy course"

Indications for consultation of other specialists

With the development of complications associated with the defeat of the nervous system, the consultation of a neurologist (encephalitis, meningoencephalitis, opticomyelitis and myelitis, polyradiculoneuritis, serous meningitis) is shown.

Consultation of the surgeon with a deep lesion of the skin and subcutaneous tissue.

Treatment of the chickenpox

Hospitalized patients with severe, complicated course of the disease and by epidemiological indications.

Chickenpox in children is rarely severe. Severe or fatal disease is more likely in adult patients with depression of T-cell immunity (eg, lymphoreticular tumor), in those receiving glucocorticoids or chemotherapy.

Chicken pox (chicken pox) in moderate cases requires only symptomatic treatment. Measures aimed at reducing itching and preventing the breakdown of crusts that predispose to secondary infection are sometimes difficult to achieve. Gauze compresses may be useful, or, with severe itching, systemic antihistamines, mucous oat baths. Simultaneous administration of large doses of systemic antihistamines can cause encephalopathy and is unacceptable.

To prevent a secondary bacterial infection, patients should regularly take a bath, keep their underwear and hands clean, and have short cut nails. Antiseptics are not used if there is no infection; the infection is treated with antibiotics.

Antiviral drugs administered to patients with immunity within 24 hours of the onset of the rash can reduce the duration and severity of the symptoms. However, since children are more likely to get sick, antiviral treatment of chickenpox is not routine. Ingestion valaciclovir, famciclovir, acyclovir is recommended for immunocompromised patients, healthy individuals at risk of serious illness, including all patients older than 12 years with skin diseases (especially eczema) or chronic lung diseases, and also receiving salicylates or glucocorticoids. Famciclovir is used for 500 mg 3 times a day, valaciclovir 1 g 3 times. Acyclovir is less desirable in use because its bioavailability when administered is lower, but it can be given at a dose of 20 mg / kg 4 times a day to a maximum dose of 3200 mg. Immunosupered children over 1 year of age should receive 500 mg / m ² every 8 hours. Patients should not go to school and work while there are crusts.

With the development of chickenpox pneumonia, inhalations of human leukocyte interferon (leukinferon) are indicated.

Local treatment of chickenpox consists in using 5-10% potassium permanganate solution or 1% alcohol solution of brilliant green in order to prevent secondary infection and faster drying of the vesicles. To reduce itching, the skin is lubricated with glycerol or wiped with water with vinegar or alcohol. Assign antihistamines (klemastin, diphenhydramine, cetirizine, acrivastine). When hemorrhagic forms are shown, vicasol, rutin, calcium chloride.

Physiotherapeutic treatment of chickenpox consists in the use of UV-irradiation for 2-3 days to accelerate the precipitation of crusts.

Dispensary observation for a month.

Approximate terms of incapacity for work - 10 days.

It is necessary to limit physical activity, to avoid overcooling, to eat in a balanced way.

Prevention

Postponed chickenpox provides lifelong immunity. All healthy children and unhealthy adults should be immunized with a live attenuated vaccine. Vaccination is especially important in women of childbearing age and adults with chronic diseases. Serological tests to determine the immune status before vaccination are usually not required. Vaccination is contraindicated in patients with severe or moderate diseases, immunocompromised patients, pregnant women taking large doses of glucocorticoids, in children taking salicylates. Although the vaccine can cause symptoms of chicken pox in healthy patients, the disease is usually mild (less than 10 papules or vesicles) and short-lived.

After contact, chickenpox (chicken pox) can be prevented or weakened by intramuscular injection of an immunoglobulin prepared from a pool of plasma with high titers of specific antibodies. Such prophylaxis should be performed in patients with leukemia, immunodeficiency and impaired patients; unvaccinated pregnant women; newborns whose mothers had chickenpox 5 days before and within 2 days after giving birth. Immunoglobulin is given intramuscularly for 4 days after contact in a dose of 12.5 U / kg (100 U / ml), but not more than 625 units. Postexposure vaccination can reduce or prevent the disease if used within 3 days and possible up to 5 days after contact. People who do not have immunity against chicken pox should avoid contact with patients.

The virus is unstable, so do not carry out disinfection. Isolation is subject to herpes zoster. Attempts to use active immunization are described. Vaccination from varicella should be carried out as quickly as possible. Developed live attenuated vaccines, which, according to the observations of their authors, provide a good effect. However, most experts consider the mass vaccination to be inexpedient.

[47], [48], [49], [50]