Rubella

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Rubella is one of the traditional childhood exanthems.

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  • We are concerned about rubella because it causes congenital rubella syndrome (CRS).
  • CRS causes severe foetal abnormalities or death.

Aetiology

Rubella virus (RUBV) is a virus of genus Rubivirus. A member of the Togaviridae family.

Taxonomy

Clinical

Rubella virus causes a mild febrile illness, with a diffuse punctate and maculopapular rash. The incubation period is from 14 to 21 days, and it is contagious from one week before and 4 days after the onset of the rash. It may cause mild arthropathy. Small discrete nodes in the posterior triangle of the neck are traditionally associated with it. In healthy individuals, it is regarded as a trivial disease.

Contents

Rubella in pregnancy

However, the real reason why we are concerned about rubella is because it causes congenital rubella syndrome (CRS).

Vaccination of teenage girls with rubella vaccine reduced the number of cases; but there were still many cases as there was no herd immunity, and many women of child-bearing age had either not been vaccinated (missed out in UK, or came from elsewhere where vaccination is not offered) or had been vaccinated but not successfully immunised. Since the introduction of MMR there has been a very dramatic reduction in CRS.

Guidelines "Guidance on the management of, and exposure to, rash illness in pregnancy" is available from the HPA website[1].

Congenital rubella syndrome

Congenital rubella syndrom was first noted by Australian paediatrict opthalmogist Normal McAlister Gregg, who noted a high rate of cataracts in infants, and made the connection between this and their mother's rubella infections in pregnancy.

CRS causes severe fetal abnormalities or death.

Rubella infection in pregnancy can interfere with organ development. Consequently, the particular damage done will depend on which organs are developing at the time of the infection. By 20 weeks of pregnancy most organogenesis is complete, and the infection is relatively harmless.

The classic triad for congenital rubella syndrome is:

  • Sensorineural deafness (58% of patients)
  • Eye abnormalities—especially retinopathy, cataract, and microphthalmia (43% of patients)
  • Congenital heart disease—especially pulmonary artery stenosis and patent ductus arteriosus (50% of patients)

Many other congenital anomalies or sequelae can be caused by rubella. Ironically, one of these is autism - the very condition for which the MMR vaccine was incorrectly blamed.[2]

Rubella is not the only pre-natal infection that can cause fetal abnormalities. Classically, paediatricians refer to the "TORCH" infections which "classically comprise toxoplasmosis, Treponema pallidum, rubella, cytomegalovirus, herpesvirus, hepatitis viruses, human immunodeficiency virus, and other infections, such as varicella, parvovirus B19, and enteroviruses".[3]

Investigations

Blood tests

There are sufficient other viral infections which produce a similar rash that definite diagnosis in populations who are mostly immunised depends on demonstrating a rise in antibodies. Usually definite diagnosis is not needed. Prior to pregnancy all women were offered determination of antibody status for Rubella, a positive test being regarded as indicating immunity. (This test was dropped in in England from 1 April 2016, in favour of increased emphasis on ensuring that all women of childbearing age who have not already received two doses of MMR vaccine do so; and that any pregnant women who have not had two doses are vaccinated postpartum.[4][5][6])

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  • Nobody is reported to have been harmed by Rubella vaccination during early pregnancy, but we avoid it.
    • Costa Rican researchers followed up women immunised (with RA27/3)in their 2001 programme who turned out to have been pregnant. Looking at 1191 mother-child pairs then report that there were no cases of CRS, and that no child was IgM positive. This strongly supports the view that the risk of immunisation is less than of non-immunisation, regardless of pregnancy. [7]
  • Any woman who has made it through pregnancy without being immune to Rubella should be offered immunisation almost as soon as they see the baby

Radiology

Treatment

Medical

Prevention

LogoKeyPointsBox.pngSince all pregnant women who come to the attention of the maternity services have - until April 2016 - had their Rubella antibody titre measured, we know the immunisation's effectiveness. It is very rare for a woman to have been immunised and have a non-immune titre, therefore the Rubella (component of MMR) immunisation is highly effective throughout - by definition - the child-bearing years.

Rubella can be safely and effectively prevented by vaccination - in the UK, the only widely available and licensed vaccine is MMR. The rubella component of the vaccine is more effective than the mumps or measles component, and gives long-lasting protection.

There has been some discussion - stirred up by anti-vaccinationists, inevitably - about whether the use of rubella vaccine is acceptable to all religious groups' but all the major religions support the use of this vaccine, albeit with reservations - see Rubella vaccine and religious groups.

External Links

References

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