Etiology and pathogenesis
Rubella virus is the sole representative of the genus Rubivirus within the family Togaviridae. It is a spherical RNA virus whose genome encodes five proteins. Virion proteins play a key role:
- E1 (envelope glycoprotein) is a hemagglutinin and the strongest immunogen, against which protective antibodies are produced.
- E2 acts as a receptor when binding to the target cell.
- C-protein is a structural capsid nucleoprotein.
The virus enters the body through the respiratory tract via receptor-mediated endocytosis. Replication occurs in regional lymph nodes, followed by a stage of viremia (hematogenous dissemination). The pathogen exhibits a tropism for mucosal epithelium, synovial membranes, skin, and embryonic tissues. It is important to understand that the onset of rash and intoxication syndrome is immune-mediated in nature.
Clinical presentation
The disease proceeds with marked cyclicity. The incubation period, prodromal period, exanthema period, and convalescence are distinguished.
A distinctive feature of the prodromal period is the early development of lymphadenopathy—specific enlargement of the posterior cervical, occipital, and postauricular nodes.
During the exanthema period, the following are observed:
- Catarrhal syndrome: dry cough, rhinitis, oropharyngeal mucosal hyperemia, scleral vessel injection.
- Intoxication syndrome: generally mild to moderate (low-grade fever).
- Exanthema: a fine maculopapular rash appears on an unchanged skin background, localized on the face, trunk, and extremities.
Due to the introduction of the immunization schedule, epidemiology has changed: the infection has "grown older." In adult patients, about 50% of cases occur in mild or atypical forms, complicating timely diagnosis.
Diagnostic Principles
A preliminary diagnosis is established based on clinical presentation and epidemiological history taking (contact with infected individuals within 21 days, vaccination status).
Differential diagnosis is performed with acute respiratory viral infections (ARVI), measles, scarlet fever, infectious mononucleosis, adenovirus infection, and toxic-allergic reactions.
Laboratory verification for sporadic incidence includes:
- Up to the 2nd day of illness: PCR diagnostics of oropharyngeal swabs, saliva, or blood.
- From days 3–4 of illness: Serological tests (ELISA, IFA) to detect IgM or low-avidity IgG.
Treatment and management tactics
Hospitalization is performed only according to epidemiological indications or in severe cases (complications). In most cases, home-based treatment is indicated:
- Isolation of the patient for the entire contagious period (up to the 5th day from the onset of the rash).
- Abundant fractional fluid intake (detoxification), antihistamines, multivitamins.
An extremely dangerous complication is rubella meningoencephalitis. If dizziness, worsening headaches, vomiting, or altered consciousness occurs, emergency medical services must be called immediately.
Contact children attending childcare facilities are quarantined from the 7th to the 17th day from the moment of contact with the patient.
Briefly: answers to topical questions
What proteins are encoded by the rubella virus genome and what functions do they perform?
The rubella virus genome encodes 5 proteins: two non-structural and three virion proteins.
- NS1 and NS2 are non-structural proteins (their functions are not specified in the sources).
- E1 is an envelope glycoprotein (hemagglutinin). It is the strongest immunogen, inducing the formation of hemagglutinating and virus-neutralizing antibodies.
- E2 is an envelope glycoprotein. It acts as a receptor during interaction with the target cell and also induces the production of virus-neutralizing antibodies. It has E2a and E2b forms.
- C-protein is a non-glycosylated capsid protein (structural nucleoprotein). It is detected in the complement fixation test.
What complications of rubella are encountered in clinical practice, aside from rubella meningoencephalitis?
Specific and nonspecific complications of acquired rubella include various systemic lesions.
- Articular: acute arthritis, chronic rubella polyarthritis.
- Hemorrhagic: hemorrhages into internal organs (brain, eyes), thrombocytopenic purpura.
- Neurological: encephalitis, encephalomyelitis, progressive rubella panencephalitis (PRPE).
- Nonspecific (secondary): pneumonia, otitis media, tonsillitis.
What congenital anomalies are included in the classic Gregg's triad upon intrauterine rubella infection?
The classic congenital rubella triad (Gregg's triad) includes:
- Cataracts.
- Deafness.
- Congenital heart defects.
To remember the main syndromes, use the acronym LEKI (in Russian): Lymphadenopathy, Exanthema, Catarrh, Intoxication.
Class and exam questions
Why is rubella critically dangerous for pregnant women?
The virus exhibits marked endotheliotropism and high teratogenic activity. Vertical transmission of the infection leads to severe congenital fetal pathology.
What are the features of the rash in typical rubella?
This is a fine maculopapular rash that appears on the face, trunk, and extremities, while the background skin remains unchanged.
Which lymph nodes react first?
Enlargement and mild tenderness of the posterior cervical, occipital, and postauricular lymph nodes are characteristic.
What else to study on this topic
- Clinical presentation and criteria for congenital rubella
- Specific diagnostic tactics for examining pregnant women with a burdened epidemiological history
- Pathomorphological changes in tissues during rubella infection
- Detailed algorithm for differential diagnosis with measles and scarlet fever
- Specific vaccine prophylaxis regimens
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