Rubella: complications and pathogenesis

Complications of acquired rubella

Specific complications in the acquired form are rare and predominantly affect adult patients. According to ICD-10, rubella with neurological complications is coded as B06.0, and with other complications (arthritis, pneumonia) as B06.8.

Typical complications include acute arthritis, which has a benign course. It occurs concurrently with the appearance of the exanthem and lasts up to several weeks. Most commonly, the knee, wrist, and hand joints are affected. The pathogenesis is associated with the penetration of the pathogen into the joint cavity—the virus is detected directly in the synovial fluid. Extremely rarely, chronic rubella polyarthritis develops, in which the virus persists in the blood.

Severe complications include:

• Hemorrhagic disorders. These are based on thrombocytopenia and increased vascular wall permeability. This leads to the development of thrombocytopenic purpura and hemorrhages into internal organs (brain, eyes).
• Neurological pathologies. These include encephalitis, meningoencephalitis, and encephalomyelitis. These are life-threatening conditions with a mortality rate of 20–40% (according to some sources, up to 50%).

Secondary microbial flora may also supervene, leading to nonspecific complications such as pneumonia, otitis media, or tonsillitis.

Pathogenesis of intrauterine lesions

Congenital rubella always carries a serious prognosis. Fetal infection leads to the development of immunological tolerance and prolonged persistence of the virus in the child's organism. This creates a high threat of delayed neurological catastrophes in the future.

The risk of congenital malformations is strictly tied to the gestational age at the time of infection:

• In early stages, the probability of malformations reaches 26–30%.
• At 9–13 weeks, the risk decreases to 8%.
• In the 4th month, it is 1.4–5.7%.
• From the 5th month onward, it does not exceed 0.4–1.7%.

In addition, the virus provokes stillbirths. In the 1st trimester of pregnancy, their frequency is about 10%, in the 2nd trimester 5%, and in the 3rd trimester 2%.

Progressive rubella panencephalitis (PRPE)

PRPE is a slow infection with a 100% mortality rate. Historically, it was associated only with congenital rubella syndrome, but since 1976 its development has also been proven in patients who underwent acquired infection in the 1st or 2nd year of life. The disease manifests in the second decade of life; prior to that, patients appear clinically healthy.

The pathogenesis of PRPE is based on the reactivation of the virus persisting in CNS neurons. The mechanism of damage includes:

1. Synthesis of specific antibodies inside the CNS with an intact blood-brain barrier.
2. Formation of lymphocytic and plasma cell infiltrates ("sleeves") around cerebral blood vessels, consisting predominantly of T and B cells, as well as CD4+ cells.
3. Development of exudative-productive vasculitis leading to degenerative-atrophic changes.

In brain tissues, progressive neuronal death, pronounced astrogliosis with glial nodules, and extensive demyelination are observed. Cell destruction is caused by the combined effect of immune (cytokine) reactions and the direct cytopathic effect of the virus on neurons, axons, and oligodendrocytes.

Clinically, PRPE manifests as slowly progressive dementia and motor disorders (facial nerve paresis, dysarthria, increased muscle tone, foot clonus). A specific feature is the complete absence of sensory disturbances. In the terminal stage, seizures occur with loss of consciousness.

Confirmation of the immunopathological nature of PRPE is the detection of high titers of specific IgG class antibodies in the cerebrospinal fluid (CSF) and blood serum. CSF analysis reveals pleocytosis, increased total protein, and gamma-globulin levels. EEG records abnormalities in frontal pathways. There is no specific treatment.

Class and exam questions

What else to study on this topic

• Clinical classification and periods of typical rubella
• Differential diagnosis with exanthema subitum and parvovirus infection
• Criteria for clinical and laboratory diagnosis of the disease
• Indications for hospitalization and principles of symptomatic therapy

Other topics in the "Respiratory Infections" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.