Basics of pathogenesis
The pathogenesis of chickenpox is a sequential chain of events, starting from the introduction of the virus to its lifelong persistence in the body.
- Introduction of the pathogen. The virus enters through the portal of entry, after which its primary replication begins. This process is localized in the epithelial cells of the mucous membranes and regional lymph nodes.
- Viremia and dissemination. Having accumulated in the lymphoid tissue, the pathogen breaks into the bloodstream. The virus spreads throughout the body.
- Tissue tropism. The virus exhibits strict tropism for specific target tissues (primarily the epithelium of the skin and mucous membranes), which clinically manifests as the formation of an exanthem.
- Outcomes. After relief of acute manifestations and elimination of the virus from the bloodstream, post-infection immunity is formed. A characteristic feature is the lifelong persistence of the virus in the body after a primary infection.
Laboratory diagnostics
The diagnosis is most often established based on clinical and epidemiological data, although specific laboratory methods are used in atypical cases or diagnostic difficulties:
- Cytological method: aimed at detecting specific Lipschütz bodies.
- Serological method (retrospective): allows the detection of a fourfold increase in antibody titer to the varicella-zoster virus in paired sera. This test is more often available in large diagnostic centers.
- Molecular genetic method: PCR testing of various biological fluids to detect the genetic material of the virus (used in complex diagnostic cases).
Principles of treatment
The vast majority of patients are treated on an outpatient basis. Hospitalization is carried out strictly according to indications:
- Clinical: severe course of the infection or development of complications.
- Epidemiological.
Outpatient treatment tactics:
- Prescription of bed rest and implementation of sanitary and hygienic measures (frequent changes of bed linen).
- Detoxification therapy (abundant fractional drinking).
- Symptomatic therapy: relief of hyperpyrexia with antipyretics, reduction of itching with antihistamines.
- Local treatment: dabbing rash elements with potassium permanganate or brilliant green solutions. Particular attention is paid to treating exanthem elements on the genitals.
- Antibacterial therapy is prescribed exclusively when pronounced pustulation develops (addition of secondary bacterial flora), accompanied by fever and intoxication syndrome.
Anti-epidemic measures
The patient poses an epidemiological hazard throughout the entire rash period. The contagious period ends only after the 5th day from the moment the last rash element appears.
The patient must be strictly isolated from individuals who do not have immunity to the infection for the entire period of contagiousness. Prophylaxis also includes current and terminal disinfection, as well as active and passive immunization methods.
Briefly: answers to topical questions
Through what portal of entry does the chickenpox virus enter the body?
The portal of entry for the chickenpox virus is the mucosal epithelium of the upper respiratory tract. After invading epithelial cells, primary replication of the pathogen occurs, followed by local replication and subsequent transport by dendritic cells and macrophages to regional lymph nodes for further dissemination.
What is the sequence of rash elements characteristic of the exanthem in chickenpox?
Chickenpox is characterized by the evolution of a typical maculopapulovesicular rash.
The development of elements occurs in the following sequence:
- Spot (macule) — initially, a pink spot with clear contours appears.
- Papule.
- Vesicle — a typical unilocular vesicle 2–5 mm in size is formed; the transformation of a papule into a vesicle occurs rapidly, within a few hours.
- Crust (scab) — resorption of the vesicle contents occurs, followed by the formation of crusts.
In which body structures does lifelong persistence of the virus occur after chickenpox?
Lifelong persistence of the varicella-zoster virus (Varicella Zoster) occurs in the sensitive ganglia of the peripheral nervous system.
The viral genome is preserved in the form of episomes in the nuclei of neurons in sensory ganglia:
- Dorsal root ganglia of the spinal cord.
- Cranial nerve ganglia.
Class and exam questions
In which cells does primary virus replication occur?
Primary replication of the varicella-zoster virus occurs in the mucosal epithelial cells and regional lymph nodes.
When are antibiotics prescribed for chickenpox?
Broad-spectrum antibiotics are used only when bacterial flora is added (pronounced pustulation), which is accompanied by symptoms of intoxication and fever.
How long is a patient considered contagious?
The contagious period lasts until the fifth day after the appearance of the last rash element.
What else to study on this topic
- Mechanism and routes of transmission of the varicella-zoster virus
- Classification and clinical course of typical and atypical forms
- Criteria for assessing the severity of the patient's condition
- Specific and non-specific complications of chickenpox
- Active and passive immunization regimens
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