Kongenitalt rubellasyndrom

Bakgrund¹

Röda hund is usually a mild, self-limiting viral infection. However, maternal rubella infection in pregnancy may result in fetal loss or in congenital rubella syndrome (CRS). CRS presents with one or more of the following:

• Cataracts and other eye defects.

• Dövhet.

• Cardiac abnormalities.

• Microcephaly.

• Retardation of intra-uterine growth.

• Inflammatory lesions of brain, liver, lungs and bone marrow.

Infection in the first 8-10 weeks of pregnancy results in damage in up to 90% of surviving infants, and multiple defects are common. The risk of damage declines to about 10-20% with infection occurring between 11 and 16 weeks gestation, and fetal damage is rare with infection after 16 weeks of pregnancy, with only deafness being reported following infections up to 20 weeks of pregnancy.

Some infected infants may appear normal at birth but perceptive deafness may be detected later.

Epidemiologi

• Rubella is now a very uncommon infection in the UK as a result of the MMR vaccination programme. In England and Wales there were no laboratory-confirmed cases of rubella in 2020 or 2021.²

• However, rubella is still common in many developing countries. The World Health Organization (WHO) estimates that worldwide over 100,000 babies are born with congenital rubella syndrome every year.³

Presentation¹

In the mother

See separate Röda hund artikel.

In the baby⁴

• Neonatal: low birth weight, interstitial pneumonitis, radiolucent bone disease, hepatosplenomegaly.

• Congenital heart defects (öppetstående ductus arteriosus, peripheral pulmonary artery stenosis, ventricular septal defects, atrial septal defects).

• Sensorineural hearing impairment.

• Cataracts, pigmentary retinopathy, microphthalmos, chorioretinitis.

• Neurological: microcephaly, cerebral calcifications, meningoencephalitis, behavioural disorders, generell inlärningssvårighet.

• Haematological: thrombocytopenia, haemolytic anaemia, petechiae/purpura, dermal erythropoiesis.

• Type 1 diabetes and thyroid disease.

Differentialdiagnos

A number of viruses can cause a rubella-like rash, so when an accurate diagnosis is imperative, as in early pregnancy, laboratory investigations must be undertaken.

In pregnancy, rubella is indistinguishable from parvovirus B19. Due to the wide differential and potential fetal risks, it is important to seek advice/follow Public Health England (PHE) guidance on rash illness and exposure to rash illness during pregnancy.⁵

The other viruses in the TORCH group (TOxoplasmosis, Rubella, Cytomegalovirus, Herpes simplex) have the following common features:

• Preterm delivery.

• Låg födelsevikt.

• Anemi.

• Thrombocytopenia.

• Hepatitis with jaundice and hepatosplenomegaly.

• Microcephaly, mental handicap, seizures and failure to thrive.

Utredningar

If a pregnant woman is suspected of having rubella, the clinical diagnosis is very unreliable.

Detection of specific IgM in saliva samples is both sensitive and specific. Serological and/or polymerase chain reaction (PCR) testing is the gold standard investigation and the local Health Protection Unit (HPU) can provide a testing kit.²

Criteria for postnatal diagnosis in the baby:

• IgM antibodies do not cross the placenta and indicate a recent infection acquired after birth.

• Unexpected persistence of rubella IgG (does not drop at two-fold dilution/month as maternal IgG does - which is cleared by six months).

• PCR is a very sensitive test for the virus.⁶

Ledning

Maternal rubella infection²

If rubella is suspected in a pregnant woman: contact the local Health Protection Team immediately. Rubella is a notifiable disease.

If rubella infection is confirmed and the woman is in the first 20 weeks of pregnancy, or there is any doubt about the gestational age: refer urgently to obstetrics (fetal medicine) for risk assessment, counselling, and management.

Beyond 20 weeks gestation there have been no published case reports of congenital rubella syndrome. If rubella infection is diagnosed in pregnancy and gestation is confirmed to be greater than 20 weeks: the woman can be reassured that there have been no reported cases of congenital rubella syndrome after this gestational age.

If the mother is found to be non-immune, rubella immunisation should not be administered in pregnancy but may be given post-partum.

Kongenitalt rubellasyndrom

• The need for special educational provision will depend on the presence/combination of mental handicap, hearing and visual defects. These should be assessed at the earliest opportunity.

• Cardiac surgery may be required.

Infants with suspected congenital rubella infection should be reported to the National Congenital Rubella Surveillance Programme, either directly to the Institute of Child Health (Tel: 020 7905 2604) or via the British Paediatric Surveillance Unit (Tel: 020 7323 7911).¹

Prognos

Prognosis depends upon the severity of the lesions, the combinations of defects present and the quality of the input to the child.

Förebyggande¹

Se även artiklarna om UK Immunisation Schedule och Measles, Mumps and Rubella Vaccination.

• Prevention of congenital rubella syndrome through immunisation of adolescents and women of childbearing age.

• Non-immune women who are planning a pregnancy and are given the MMR vaccine should wait 4 weeks before trying to conceive again, because of the theoretical risk of neonatal rubella from the live rubella in MMR.

• Achievement and maintenance of the required high vaccination coverage and high-quality surveillance of rubella and CRS, including laboratory testing of all suspected cases, are fundamental to eliminate rubella and prevent CRS in Europe.⁷

• Checking rubella immunity should occur as part of preconception counselling.

• Because the clinical diagnosis is so unreliable, a history of having had the disease is inte a reason to forgo immunisation.

• Immunoglobulin is not recommended for the protection of pregnant women exposed to rubella. It should only be considered when termination of pregnancy is unacceptable.