Rubella Virus 

Rubella virus has many properties which are unique among the Togaviruses, which is the reasoning behind its classification within its own genus: Rubivirinae.  It is the only Togavirus known to be transmitted via the respiratory route, and the disease with which it is associated, Rubella or "German Measles" was once ubiquitous in human populations.  Rubella virus can also act as a teratogen, inducing Congenital Rubella Syndrome when spread from mother to fetus in the first trimester of pregnancy.

Rubella in the Child and Adult:

•  Incubation:  2-3 weeks
• Epidemiology:  Rubella virus is spread via respiratory transmission from human to human.  Virus is shed in oropharyngeal secretions and is highly transmissible.  In communities where vaccination is rare, spring outbreaks typically occur every few years.  In these communities, children represent the largest number of cases, as adults usually acquire lifelong immunity after the primary infection.
• Symptoms and Outcomes:  The primary symptom of Rubella virus infection is usually the appearance of fine, pink macules on the face.  This rash typically spreads to the trunk and limbs and fades within 48 hours.  However, in up to 1/2 of all cases, no rash may be apparent.  Enlargement of postauricular, suboccipital, and posterior cervical lymph nodes is also common.  In adult females, mild polyarthritis may occur.  Rubella virus infection typically has no lasting effect.  Rare complications of Rubella virus infection include thrombocytopenic purpura and postinfectious encephalopathy.
• Pathology and Pathogenesis:  Rubella virus enters via inhalation and infects cells of the respiratory tract.  It is then spread via the lymph nodes to the blood, where it induces an immune response which leads to lasting immunity.
• Prevention and Management:  The live, attenuated Rubella virus vaccine is given universally to young children in the US and many other developed countries.  It is given in two shots (at 15 months and 5 years) and produces lasting immunity in more that 90% of recipients.  Management of Rubella virus infections is typically symptomatic.

     Congenital Rubella Syndrome: 

    Congenital Rubella Syndrome (CRS) is caused by infection of the fetus in utero during the first trimester of pregnancy.  This occurs only when the mother acquires a primary Rubella infection during the first trimester.  20% of the children born after such an infection suffer the severe congenital abnormalities associated with CRS.  These include neurosensory deafness, blindness, congenital heart disease, microcephaly with mental retardation, growth retardation, and hepatosplenomegaly.  10-20% of these children die within the first year of life.
    Due to the risk of CRS, unvaccinated women should be immunized against Rubella at least 3 months prior to conception.
 

Graphics obtained from MMWR vol. 46

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