Epidemiology
The disease is a strict anthroponosis — humans are the only source of infection. This can be a patient with a clinically manifest or latent course, as well as a child with congenital rubella.
An infected person is most contagious in the second half of the incubation period and during the week after the rash appears. Children with congenital pathology can shed the causative agent in urine, feces, and nasopharyngeal secretions for a very long time — up to two years. Interestingly, virus strains from such children exhibit higher virulence, and these specific patients can become the source of airborne transmission of the infection to those around them.
Main routes of transmission:
- Airborne route is the main transmission mechanism upon contact with an infected person. The virus is not highly stable in the external environment, so the contagiousness of the disease is lower than that of measles or chickenpox. Infection requires prolonged and close contact.
- Transplacental (vertical) route — transmission from a pregnant mother to the developing fetus.
The incidence typically has an outbreak pattern, particularly in children's groups. An epidemic surge begins when the proportion of non-immune individuals in the population reaches or exceeds 15%.
Clinical Forms
The infection can occur in two main variants that differ fundamentally in their infection mechanism and clinical manifestations: acquired and congenital forms. Overall, three pathological conditions caused by the virus are distinguished:
- Acquired rubella (classic clinical presentation).
- Congenital rubella (the result of fetal infection).
- Progressive rubella panencephalitis (an extremely severe complication).
The disease leaves behind persistent lifelong immunity, regardless of the form contracted.
Pathogenesis and clinical presentation of acquired rubella
The virus enters the body through the mucous membranes of the upper respiratory tract. Primary replication takes place there, in the regional lymph nodes. Then the causative agent enters the bloodstream (the viremia stage sets in) and spreads throughout the body, settling in the lymph nodes and skin epithelial cells. The rash in rubella is a consequence of an immune inflammatory reaction in the skin.
The clinical picture develops sequentially:
- The incubation period lasts from 11 to 24 days.
- In the prodromal period, mild catarrhal symptoms, conjunctivitis, and a low-grade fever are observed.
- A pathognomonic symptom is enlargement of the posterior cervical and occipital lymph nodes (the so-called "rubella horns").
- The rash period is characterized by the appearance of a maculopapular rash all over the body.
In children, the infection usually runs a mild course. The virus leaves the bloodstream as early as two days after the rash appears, but can be detected in upper respiratory tract secretions for up to two weeks. Sometimes complications develop: arthritis, meningitis, encephalitis, or thrombocytopenic purpura.
Serological diagnostics
During the disease, a transient secondary cellular immunodeficiency occurs. Serological markers are used for diagnostics and determination of immune status:
- Antihemagglutinins and virus-neutralizing antibodies — their high titers indicate the presence of protection, and they persist for life.
- Complement-fixing antibodies — circulate in the blood for only a few years, so their detection indicates a recently suffered infection.
Briefly: answers to topical questions
What is the classification and structure of the rubella virus?
The rubella pathogen is an RNA-containing virus, the sole representative of the genus Rubivirus of the family Togaviridae. The virion has a spherical shape (60–70 nm in diameter) and contains a single-stranded linear (+)-RNA.
The structure of the virus includes:
- Supercapsid — a lipid layer with "spikes" made of virion envelope glycoproteins E1 (hemagglutinin, a potent immunogen) and E2 (the receptor for cell interaction).
- Nucleocapsid — located inside the envelope, consisting of RNA and the structural non-glycosylated C protein.
The viral genome also encodes two non-structural proteins (NS1 and NS2).
What malformations are included in the classic Gregg syndrome in congenital rubella?
Classic Gregg syndrome (congenital rubella syndrome) includes the characteristic triad of severe fetal malformations that develops upon early intrauterine infection.
This triad includes:
- Eye pathology — most commonly cataracts, which are a classic sign, as well as glaucoma, microphthalmia, and chorioretinitis.
- Congenital heart defects — patent ductus arteriosus (Botallo's duct), pulmonary trunk stenosis, ventricular and atrial septal defects.
- Deafness — caused by various malformations of the auditory organs.
What are the clinical manifestations and features of progressive rubella panencephalitis?
Progressive rubella panencephalitis (PRPE) is a slow viral infection resulting from prolonged persistence of the virus in the body.
Features and clinical manifestations of the disease:
- Timing of development — manifests in the second decade of life in individuals who had acquired infection in childhood, or in children with congenital rubella.
- Clinical presentation — characterized by progressive impairment of mental and motor functions of the central nervous system.
- Prognosis — unfavorable, the disease ends in death.
- Epidemiological significance — patients are absolutely non-contagious, as the virus is absent from their secretions.
What specific prophylaxis and vaccine prophylaxis are used against rubella?
Specific prophylaxis for rubella is carried out using live vaccines from attenuated virus strains.
Combined vaccines are used for immunization, such as the measles, mumps, and rubella (MMR) vaccine.
According to the National Immunization Schedule of the Russian Federation, routine vaccination is administered to children at 12–15 months of age, with revaccination at 6 years. Additional immunization covers all unvaccinated children, those who have not had the disease, or those with only one vaccination up to 18 years of age, as well as women aged 18–25.
The main goal of prophylaxis is to protect pregnant women and prevent congenital rubella syndrome.
The "rubella horns" symptom refers to enlarged posterior cervical and occipital lymph nodes. Imagine horns growing on the back of the head due to rubella.
Class and exam questions
Why is the contagiousness of rubella lower than that of measles?
This is due to the instability of the rubella virus in the external environment. Successful transmission requires prolonged and close contact with the source of infection.
Which biological fluids are contagious?
The virus is excreted in upper respiratory mucous secretions, urine, and feces.
How long are infants with congenital rubella contagious?
Children with congenital rubella can shed the virus into the environment for a very long time — up to 2 years.
What level of susceptible population triggers an outbreak?
An epidemic surge in incidence occurs when the proportion of individuals lacking immunity to the virus is 15% or more.
What else to study on this topic
- Features of the pathogenesis of congenital rubella
- Specific manifestations of congenital rubella syndrome
- Mechanism of development of progressive rubella panencephalitis
- Differential diagnosis of rash in rubella, measles, and scarlet fever
- Specific prevention (vaccination) schedules for rubella
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