Chickenpox is an acute infectious disease of viral etiology characterized by the appearance of a characteristic bubble rash against the background of a general intoxication syndrome. The causative agent of chickenpox is the herpes virus type 3, transmitted from the patient by airborne droplets. Chickenpox is one of the most common childhood infections. It is manifested by characteristic abundant itchy vesicular rashes that appear at the height of fever and general infectious manifestations. A typical clinic allows you to diagnose the disease without conducting any additional research. Treatment of chickenpox is mainly symptomatic. Antiseptic treatment of rash elements is recommended to prevent secondary infection.
Chickenpox is an acute infectious disease of viral etiology characterized by the appearance of a characteristic bubble rash against the background of a general intoxication syndrome.
Chickenpox is caused by the Varicella Zoster virus of the herpesvirus family, aka the human herpes virus type 3. This is a DNA-containing virus, little stable in the external environment, capable of replication only in the human body. Inactivation of the virus occurs fairly quickly when exposed to sunlight, ultraviolet radiation, heating, drying. The reservoir and source of chickenpox are sick people during the last 10 days of the incubation period and the fifth to seventh days of the rash period.
Chickenpox is transmitted by an aerosol mechanism by airborne droplets. Due to the weak resistance of the virus, contact-household transmission is difficult to implement. The spread of the virus with a fine aerosol released by patients when coughing, sneezing, talking, is possible for a sufficiently large distance within the room, it is likely to drift with the current of air into adjacent rooms. There is a possibility of transmission of the infection transplacentally.
People have a high susceptibility to infection, after suffering from chickenpox, a tense lifelong immunity remains. Children of the first months of life are protected from infection by antibodies received from the mother. Chicken pox most often affects children of preschool and primary school age who attend organized children’s groups. About 70-90% of the population have chickenpox before the age of 15. The incidence in cities is more than 2 times higher than in rural settlements. The peak incidence of chickenpox occurs in the autumn-winter period.
The entrance gate of infection is the mucous membrane of the respiratory tract. The virus is introduced and accumulates in the epithelial cells, subsequently spreading to the regional lymph nodes and further into the general bloodstream. The circulation of the virus with the blood flow causes the phenomena of general intoxication. The chickenpox virus has an affinity for the epithelium of the integumentary tissues. Replication of the virus in the epithelial cell contributes to its death, in place of dead cells there are cavities filled with exudate (inflammatory fluid) – a vesicle is formed. After opening the vesicles, crusts remain. After separating the crust, a newly formed epidermis is found under it. Rashes with chickenpox can form both on the skin and on the mucous membranes, where vesicles progress quickly enough in erosion.
Chickenpox in people with a weakened immune system is severe, contributes to the development of complications, secondary infection, exacerbation of chronic diseases. During pregnancy, the probability of transmission of chickenpox from the mother to the fetus is 0.4% in the first 14 weeks and increases to 1% up to 20 weeks, after which there is practically no risk of infection of the fetus. As an effective preventive measure, pregnant women suffering from chickenpox are prescribed specific immunoglobulins that help reduce the likelihood of transmission of infection to the child to a minimum. Chickenpox, which developed a week before delivery and in the month following delivery, is more dangerous.
Persistent lifelong immunity reliably protects the body from repeated infection, however, with a significant decrease in the immune properties of the body, adults who had chickenpox in childhood may become infected with it again. There is a phenomenon of latent carriage of the chickenpox virus, which accumulates in the cells of nerve nodes and is able to activate, causing shingles. The mechanisms of viral activation with such a carrier are not yet clear enough.
The incubation period of chickenpox ranges from 1-3 weeks. In children, prodromal phenomena are poorly expressed, or not observed at all, in general, the course is mild with a slight deterioration in the general condition. Adults are prone to a more severe course of chickenpox with pronounced symptoms of intoxication (chills, headache, body aches), fever, nausea and vomiting are sometimes noted. Rashes in children may occur unexpectedly against the background of the absence of any general symptoms. In adults, the period of rashes often begins later, fever with the appearance of rash elements may persist for some time.
A rash with chickenpox has the character of bullous dermatitis. Rashes are single elements that occur on any parts of the body and spread without any regularity. The elements of the rash initially represent red spots, progressing into papules, and then into small smooth single-chamber vesicles with a clear liquid, falling off when punctured. The opened vesicles form crusts. Chickenpox is characterized by the simultaneous existence of elements at different stages of development and the emergence of new ones (sprinkling).
A rash with chickenpox causes intense itching, when combing, infection of vesicles with the formation of pustules is possible. Pustules during healing can leave a scar (smallpox). Uninfected vesicles do not leave scars, after the separation of the crusts, a healthy new epithelium is found. With suppuration of the rash elements, the general condition usually worsens, intoxication worsens. Rash in adults is usually more abundant, and in the vast majority of cases, pustules form from vesicles.
The rash spreads almost over the entire surface of the body with the exception of the palms and soles, mainly localized in the scalp, face, neck. Falling asleep (the appearance of new elements) is possible for 3-8 days (in adults, as a rule, they are accompanied by new feverish waves). Intoxication subsides simultaneously with the cessation of spills. The rash may appear on the mucous membranes of the oral cavity, genitals, and sometimes on the conjunctiva. The rash elements on the mucous membranes progress into erosion and ulcers. In adults, the rash may be accompanied by lymphadenopathy, for children, the lesion of lymph nodes is not characteristic.
In addition to the typical course, there is an erased form of chickenpox, occurring without signs of intoxication and with a short-term rare rash, as well as severe forms, differing in bullous, hemorrhagic and gangrenous. The bullous form is characterized by a rash in the form of large flabby blisters that leave long-healing ulcerative defects after opening. This form is typical for people with severe chronic diseases. Hemorrhagic form is accompanied by hemorrhagic diathesis, small hemorrhages are noted on the skin and mucous membranes, nosebleeds may occur. Vesicles have a brownish tint due to hemorrhagic contents. In persons with a significantly weakened body, chickenpox can occur in a gangrenous form: rapidly growing vesicles with hemorrhagic contents are opened with the formation of necrotic black crusts surrounded by a rim of inflamed skin.
In the vast majority of cases, the course of chickenpox is benign, complications are noted in no more than 5% of patients. Among them, diseases caused by secondary infection prevail: abscesses, phlegmons, in severe cases – sepsis. A dangerous, difficult-to-treat complication is viral (chickenpox) pneumonia. In some cases, chickenpox can provoke keratitis, encephalitis, myocarditis, nephritis, arthritis, hepatitis. Severe forms of diseases in adults are prone to complications, especially with concomitant chronic pathologies and a weakened immune system. In children, complications are noted in exceptional cases.
Diagnosis of chickenpox in clinical practice is based on a characteristic clinical picture. The general blood test for chickenpox is nonspecific, pathological changes may be limited to an acceleration of ESR, or signal an inflammatory disease with an intensity proportional to the general intoxication symptoms.
Virological examination involves the detection of virions by electromicroscopy of vesicular fluid stained with silver. Serological diagnostics is of retrospective importance and is performed with the help of CBR, HIR in paired sera.
Chickenpox is treated on an outpatient basis, except in cases of severe course with intense general intoxication manifestations. Etiotropic therapy has not been developed, in the case of the formation of pustules, antibiotic therapy is resorted to with a short course in medium dosages. People with immune deficiency can be prescribed antiviral drugs: acyclovir, vidarabine, interferon alpha (interferon of the new generation). Early administration of interferon contributes to a lighter and shorter-term course of infection, and also reduces the risk of complications.
Chickenpox therapy includes skin care measures to prevent purulent complications: vesicles are lubricated with antiseptic solutions: 1% solution of brilliant green, concentrated potassium permanganate (“zelenka”, “potassium permanganate”). Ulceration of the mucosa is treated with hydrogen peroxide in 3% dilution or ethacridine lactate. Intense itching in the area of rashes is relieved by lubricating the skin with glycerin or wiping with diluted vinegar, alcohol. Antihistamines are prescribed as a pathogenetic agent. Pregnant women and patients with severe form are prescribed a specific anticonvulsant immunoglobulin.
Prognosis and prevention
The prognosis is favorable, the disease ends with recovery. Vesicles disappear without traces, pustules can leave smallpox scars. Significant deterioration of the prognosis in people with immunodeficiency, severe systemic diseases.
Prevention of chickenpox consists in preventing the introduction of infection into organized children’s groups, for which quarantine measures are carried out when cases of the disease are detected. Patients are isolated for 9 days from the moment of the appearance of rashes, children who have been in contact with patients are separated for 21 days. If the day of contact with the patient is precisely determined, the child is not allowed in the children’s collective from 11 to 21 days after contact. Contact children who have not previously had chickenpox, with weakened immunity, are prescribed anti-varicella immunoglobulin as a preventive measure.
Recently, vaccination against chickenpox has been used. Varilrix (Belgium) and Okavax (Japan) vaccines are used for this purpose.