Chickenpox (varicella)

Chickenpox (varicella) is an acute systemic disease, usually in children, caused by the varicella-zoster virus (human herpesvirus type 3). The disease usually begins with mild systemic symptoms, followed by a rapid skin rash that spreads rapidly and manifests as a macule, papule, vesicle, and crust. The diagnosis is clinical. Persons 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.

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Epidemiology

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

The incidence is characterized by pronounced seasonality, reaching a maximum in the autumn-winter months. Children are the most susceptible. Post-infection immunity is intense, supported by the persistence of the virus in the body. When its intensity decreases, herpes zoster occurs.

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Causes chicken pox

The cause of chickenpox is the Varicella zoster virus of the Herpesviridae family. The virus is 150 to 200 nm in size and is found in chickenpox blisters during the first 3-4 days of the disease; after the 7th day, the virus cannot be detected. The genome has a double-stranded linear DNA molecule and a lipid membrane. The virus reproduces only in the nucleus of infected human cells. The identity of the virus that causes shingles and the chickenpox virus has been established. The virus is unstable in the environment and quickly dies; in droplets of mucus and saliva, the virus persists for no more than 10-15 minutes. Heating, sunlight, and UV radiation quickly inactivate it.

Chickenpox is highly contagious and spreads by airborne droplets, especially during the prodrome and early period of rashes. The infectious period is defined as 48 hours from the first rash until the appearance of crusts. Direct transmission (from carriers) is impossible.

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

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Pathogenesis

The entry point of the chickenpox virus is the mucous membranes of the upper respiratory tract, where the virus replicates, then the pathogen enters the blood through the lymphatic pathways. At the end of the incubation period, viremia develops. The virus is fixed in cells of ectodermal origin, mainly in the epithelial cells of the skin and mucous membranes of the respiratory tract, oropharynx. Intervertebral ganglia, cerebellar cortex and cerebral hemispheres, subcortical ganglia may be affected. In rare cases, with a generalized form, the liver, lungs, and gastrointestinal tract are affected. 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: eyes. In the liver, kidneys, lungs and central nervous system, small foci of necrosis with hemorrhages at the periphery are detected.

In pathogenesis, a significant role is given to cellular immunity, mainly the T-lymphocyte system, the suppression of which leads to a more severe course of the disease. After the acute manifestations of the primary infection subside, the virus persists in the spinal nerve ganglia for life.

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Symptoms chicken pox

The incubation period of chickenpox lasts from 10 to 21 days; with the introduction of normal human immunoglobulin, it can be extended to 28 days.

Prodromal symptoms of chickenpox are usually absent, and short-term subfebrile temperature is rarely observed against the background of deterioration of general health. Vesicles usually appear simultaneously with an increase in temperature or several hours later. With abundant exanthema, the temperature can rise to 39 C and above. The rash appears in waves over 2-4 days and is accompanied by an increase in temperature. The rash is localized on the face, scalp, trunk and limbs.

On the palms and soles it is found only with abundant rashes. The elements of the rash initially look like small maculopapules, which within a few hours turn into vesicles of a round or oval shape, and a size of 2-5 mm. They are located superficially and on a non-infiltrated base, their wall is tense, shiny, the content is transparent, but in some vesicles it becomes cloudy. Most vesicles are surrounded by a narrow border of hyperemia. Vesicles dry up in 2-3 days. Crusts form in their place, which fall off in 2-3 weeks. After the crusts fall off, scars, as a rule, do not remain. Rashes are also observed on the conjunctiva, mucous membranes of the oropharynx, sometimes the larynx, genitals. Vesicles on the mucous membranes quickly turn into erosions with a yellowish-gray bottom, which epithelialize in a few days. Rashes on the mucous membrane of the larynx and trachea, accompanied by swelling of the mucous membrane, can cause a rough cough, hoarseness, and in rare cases, croup. Rashes on the mucous membrane of the labia pose a risk of developing vulvovaginitis. Rashes are often accompanied by enlarged lymph nodes.

By the end of the first week of the disease, simultaneously with the drying of the vesicles, the temperature normalizes, the patient's well-being improves. At this time, many patients are bothered by skin itching.

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

In immunocompetent children, chickenpox is rarely severe. In adults and immunocompromised children, the infection can be severe. Mild headache, low-grade fever, and malaise may be present 11-15 days after infection and last for about 24-36 hours after the rash appears. These problems are most likely in patients over 10 years of age and are especially severe in adults.

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Forms

The following clinical forms of chickenpox are distinguished:

Downstream:

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

By severity:

• lungs;
• moderate;
• heavy:
• with severe general intoxication;
• with pronounced changes on the skin.

Typical and atypical chickenpox (varicella) are distinguished. Typical cases include cases with a characteristic rash. Typical chickenpox most often occurs in a mild to moderate form. A severe form of the disease occurs rarely, more often in weakened children and adults, it is characterized by a long-term remittent fever of up to 6-8 days. The following symptoms of chickenpox are noted: headache, possible vomiting, meningeal syndrome, impaired consciousness, arterial hypotension, convulsions. The rash is abundant, large, its metamorphosis is slow, elements with an umbilical depression in the center are possible, resembling elements of the rash in smallpox.

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

The rudimentary form is more often observed in children who received immunoglobulins, plasma during the incubation period. The rash is not abundant, roseolous-papular with isolated very small vesicles. The general condition is not disturbed.

Hemorrhagic chickenpox is very rare in severely weakened patients suffering from hemoblastosis or hemorrhagic diathesis, while taking glucocorticoids and cytostatics. On the 2nd-3rd day of the rash, the contents of the vesicles become hemorrhagic. Hemorrhages in the skin and mucous membranes, nosebleeds and other manifestations of hemorrhagic syndrome appear. A fatal outcome is possible.

Gangrenous chickenpox is very rare. It develops in emaciated patients, with poor care, creating the possibility of secondary infection. At first, individual vesicles take on a hemorrhagic character, then a significant inflammatory reaction occurs in their surroundings. Subsequently, a hemorrhagic scab is formed, after which deep ulcers with a dirty bottom and steep or undermined edges are exposed. The ulcers, due to progressive gangrenous decay of tissue, increase in size, merge, taking on significant dimensions. Complications of a purulent-septic nature often occur. The general condition of the patient is severe, the course of the disease is long.

Generalized (visceral) form. Occurs mainly in newborns, sometimes in adults with immunodeficiency. Characterized by hyperthermia, intoxication, and damage to internal organs. Mortality is high. Autopsy reveals small foci of necrosis in the liver, lungs, pancreas, adrenal glands, thymus, spleen, and bone marrow.

Chickenpox is dangerous for the fetus and newborn. If a woman develops the disease at the end of pregnancy, premature birth and stillbirth are possible. If chickenpox occurs in the early stages of pregnancy, the fetus may become infected intrauterine with the development of various malformations. The probability of newborns becoming ill is 17%, and their death is 30%. Congenital chickenpox (varicella) is severe, accompanied by severe visceral lesions.

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Complications and consequences

A secondary bacterial infection (streptococci and staphylococci) may join in, causing cellulitis and, rarely, streptococcal toxic shock. The most common complication of chickenpox is a bacterial superinfection caused by Streptococcus pyogenes and Staphylococcus aureus. In this case, the contents of the vesicles suppurate, forming pustules. Impetigo or bullous pyoderma may develop.

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

Myocarditis, transient arthritis and hepatitis, hemorrhagic complications may occur.

Encephalopathy occurs in less than 1 in 1,000 patients, usually with resolution of the disease or within the first two weeks. Most often, these symptoms of chickenpox (varicella) resolve, although rarely they can persist for a long time or lead to death. One of the most common neurologic complications is acute postinfectious cerebellar ataxia. Transverse myelitis, cranial nerve palsy, and multiple sclerosis-like manifestations may also occur. A rare but very severe complication in children may be Reye's syndrome, which begins 3-8 days after the onset of the rash; aspirin increases the risk. In adults, encephalitis occurs in 1-2 cases per 1,000 patients, which can be life-threatening.

The incidence of encephalitis does not depend on the severity of the disease. Most often, complications occur on the 5th-8th days of the disease. Cases of encephalitis development during the rash and even before the rash appear have been described. It has been noted that the earlier encephalitis begins, the more severe it is. Encephalitis manifests itself acutely with impaired consciousness, convulsions only in 15-20% of patients. In other cases, focal symptoms dominate, which increase over several days. Cerebellar and vestibular disorders are most typical. Ataxia, head tremor, nystagmus, scanned speech, intention tremor, and incoordination are noted. Pyramidal signs, hemiparesis, and cranial nerve paresis are possible. Spinal symptoms are rarely observed, in particular, pelvic disorders. Meningeal syndrome is weakly expressed or absent. In some patients, lymphocytic pleocytosis, increased protein and glucose levels are found in the cerebrospinal fluid. The course of the disease is benign, since neurons are rarely affected, only when encephalitis develops in the early stages. Adverse long-term effects are rare.

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Diagnostics chicken pox

Chickenpox diagnosis is usually straightforward. The diagnosis is made primarily on the basis of clinical data, taking into account the epidemiological history. Chickenpox should be suspected in patients with a characteristic rash. It should be remembered that similar rashes occur in other patients with viral skin lesions.

If necessary and in diagnostically unclear cases, viroscopic, virological, serological and molecular biological methods are used. Virusoscopic diagnostics of chickenpox consists of staining the contents of the vesicle with silvering (according to M.A. Morozov) to detect the virus using a conventional light microscope. The virological method is practically not used. Of the serological methods, RSK, RIMF, and ELISA are used. The main method of laboratory diagnostics is the molecular biological method (PCR).

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Differential diagnosis

Differential diagnostics of chickenpox include herpetic rash in herpes simplex, herpes zoster, vesicular rickettsiosis, impetigo and smallpox. It is necessary to exclude Kaposi's herpetic eczema, as well as infections caused by Coxsackie and ECHO viruses.

Beginning with short-term malaise, weakness, subfebrile body temperature, sore throat for 2 days

EAT

The research is ongoing

The appearance of a rash on the 1st-3rd day of illness on the face, scalp, spreading to the trunk and limbs, mucous membranes. Simultaneous deterioration of health, increased body temperature, the appearance of symptoms of intoxication (headache, weakness, vomiting)

EAT

The research is ongoing

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

EAT

The research is ongoing

History of contact with a patient with chickenpox 2 weeks before illness

EAT

The clinical diagnosis is: "Chickenpox, moderate course"

Indications for consultation with other specialists

In the event of complications associated with damage to the nervous system, a consultation with a neurologist is indicated (encephalitis, meningoencephalitis, optic myelitis and myelitis, polyradiculoneuritis, serous meningitis).

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

Treatment chicken pox

Patients are hospitalized in cases of severe, complicated disease and according to epidemiological indications.

Chickenpox in children is rarely severe. Severe or fatal disease is more common in adults with depressed T-cell immunity (eg, lymphoreticular neoplasm) or receiving glucocorticoids or chemotherapy.

Chickenpox (varicella) in moderate cases requires only symptomatic treatment. Measures aimed at reducing itching and preventing the breakdown of crusts, which predispose to secondary infection, are sometimes difficult to implement. Gauze compresses or, in case of severe itching, systemic antihistamines, mucous oat baths may be useful. The simultaneous administration of large doses of systemic antihistamines may cause encephalopathy and is unacceptable.

To prevent secondary bacterial infection, patients should bathe regularly, keep their underwear and hands clean, and keep their nails trimmed short. Antiseptics are not used unless there is an infection; the infection is treated with antibiotics.

Antiviral drugs given orally to immunocompromised patients within 24 hours of the onset of the rash may reduce the duration and severity of symptoms. However, since the disease most often affects children, antiviral treatment of chickenpox is not routine. Oral administration of valacyclovir, famciclovir, and acyclovir is recommended for immunocompromised patients, healthy individuals at risk of severe disease, including all patients over 12 years of age with skin diseases (especially eczema) or chronic lung diseases, and those receiving salicylates or glucocorticoids. Famciclovir is used at 500 mg 3 times a day, valacyclovir 1 g 3 times. Acyclovir is less desirable for use, since its bioavailability when taken orally 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. Immunocompromised children over 1 year of age should receive 500 mg/ ^m2 every 8 hours. Patients should not go to school or work while they have the crusts.

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

Local treatment of chickenpox involves using a 5-10% solution of potassium permanganate or a 1% alcohol solution of brilliant green to prevent secondary infection and to dry the blisters faster. To reduce itching, the skin is lubricated with glycerol or wiped with water and vinegar or alcohol. Antihistamines are prescribed (clemastine, diphenhydramine, cetirizine, acrivastine). For hemorrhagic forms, vicasol, rutin, calcium chloride are indicated.

Physiotherapeutic treatment for chickenpox involves the use of UV radiation for 2-3 days to speed up the shedding of crusts.

Outpatient observation for a month.

Approximate period of incapacity for work - 10 days.

You should limit physical activity, avoid hypothermia, and eat a balanced diet.

Prevention

A history of chickenpox provides lifelong immunity. All healthy children and adults who have not had chickenpox should be immunized with a live-attenuated vaccine. Vaccination is especially important in women of childbearing age and adults with chronic medical conditions. Serologic testing to determine immune status before vaccination is usually not required. Vaccination is contraindicated in patients with moderate or severe disease, immunocompromised patients, pregnant women taking high doses of glucocorticoids, and children taking salicylates. Although the vaccine may cause symptoms of chickenpox in healthy patients, the disease is usually mild (less than 10 papules or vesicles) and short-lived.

After exposure, varicella (chickenpox) can be prevented or attenuated by intramuscular administration of immune globulin prepared from pooled plasma with high titers of specific antibodies. Such prophylaxis should be given to patients with leukemia, immunodeficiencies, and weakened patients; unvaccinated pregnant women; newborns whose mothers had chickenpox 5 days before and for 2 days after delivery. Immunoglobulin is given intramuscularly for 4 days after exposure at a dose of 12.5 U/kg (100 U/ml), but not more than 625 U. Postexposure vaccination can attenuate or prevent the disease if given within 3 days and is possible up to 5 days after exposure. People who do not have immunity against chickenpox should avoid contact with sick people.

The virus is unstable, so disinfection is not carried out. Patients with herpes zoster are subject to isolation. Attempts to use active immunization are described. Vaccination against chickenpox should be carried out as quickly as possible. Live attenuated vaccines have been developed, which, according to the observations of their authors, provide a good effect. However, most specialists consider mass vaccination inappropriate.

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