Rubella

Rubella testing in pregnancy does not attempt to identify current affected pregnancies. Instead, it aims to identify women who are non-immune, so that they can be vaccinated after the birth and future pregnancies are protected against rubella infection and its consequences.

37.1 Background

Rubella (German measles) is usually a mild self-limiting disease with few complications. However, if contracted during the first trimester, it can affect the pregnancy and lead to congenital rubella syndrome at birth. Preventing congenital infection relies on maintaining high levels of immunity to rubella in the general population. There is no treatment to prevent or reduce mother-to-child transmission of rubella once infection has been detected in pregnancy. Rubella vaccination is contraindicated in pregnancy.

37.1.1 Rubella infection and immunity in Australia

• Diagnoses of rubella: In 2014, there were 17 diagnoses of rubella (0.1 per 100,000 population) NNDSS 2016. Most notified cases were women (65%), with 64% being of childbearing age (15–44 years).
• Geographical distribution: Rates of diagnosis of rubella were low and fairly consistent across jurisdictions in 2014, ranging from no reported diagnoses in the Australian Capital Territory, Northern Territory and Tasmania to 0.1 per 100,000 population in Queensland, Victoria, New South Wales, South Australia and Western Australia NNDSS 2016.
• Congenital rubella syndrome: This is rare in Australia and in recent years has mainly occurred among infants of women who were born overseas NNDSS 2016.
• Risk factors: In Australia, populations at risk of non-immunity to rubella have been identified as including:
  • women born overseas who may not have received rubella vaccines in their countries of birth Francis et al 2003, Sathanandan et al 2005 and are twice as likely to be non-immune than Australian-born women, with a higher likelihood of non-immunity among women born in Asia (Sathanandan et al 2005)
  • Aboriginal and Torres Strait Islander women from rural and remote communities, with fewer than 75% of women tested antenatally having adequate levels of immunity (compared with more than 90% of women living in an urban area) (Hunt & Lumley 2004)
  • women 35 years of age or older, who were found to be twice as likely to be non-immune as younger women, possibly due to declining immunity over time (Sathanandan et al 2005).

37.1.2 Risks associated with rubella infection in pregnancy

Maternal rubella infection can result in spontaneous miscarriage, fetal infection, stillbirth, or fetal growth restriction (Reef et al 2000). Congenital infection is most likely if the maternal infection occurs in the first 16 weeks of pregnancy, with congenital rubella syndrome occurring in all fetuses infected before the 11th week and in 35% of those infected at 13–16 weeks (Miller et al 1982). If infection occurs after 16 weeks of pregnancy, the risk of fetal damage is negligible.

Features of congenital rubella syndrome include cardiac defects, deafness, ocular defects, thrombocytopenic purpura, haemolytic anaemia, enlarged liver and spleen, and inflammation of the meninges and brain (Sanchez et al 2010). Pneumonitis, diabetes, thyroid dysfunction and progressive panencephalitis are other late expressions of the syndrome Weil et al 1975, Cooper et al 1995.

37.2 Testing for rubella non-immunity

The NICE guidelines reviewed the evidence on rubella testing in pregnancy and found:

• high sensitivity and specificity of tests for immunity (Grangeot-Keros & Enders 1997)
• high rates of congenital infection among babies born to women with symptoms of rubella in the first 12–16 weeks of pregnancy Miller et al 1982, Grillner et al 1983
• no association between congenital infections and inadvertent rubella vaccination in pregnancy CDC 2001.

The lack of association between inadvertent vaccination in pregnancy and congenital rubella syndrome has been substantiated in subsequent prospective cohort studies Bar-Oz et al 2004, Hamkar et al 2006, Badilla et al 2007, with no cases reported.

37.3 Practice summary: rubella testing

When

Early in antenatal care.

Who

• Midwife
• GP
• obstetrician
• Aboriginal and Torres Strait Islander health worker
• multicultural health worker.

What

• Discuss rubella non-immunity
  Explain that it is important to find out whether a woman is immune to rubella because of the effects that infection can have on the pregnancy and the baby.
• Document and follow-up
  Note the results of rubella testing in the woman’s record. Have a follow-up system in place so that non-immune women are offered vaccination after the birth. Some women may not develop immunity even after repeated vaccination.
• Take a holistic approach
  If a woman is found to be non-immune to rubella, offer advice on symptoms and transmission of rubella so that she can avoid contact as far as possible. Advise vaccination of family members who may also be non-immune.
• Report inadvertent vaccination
  Report inadvertent vaccination with MMR (or MMRV) to the jurisdictional immunisation unit to enable follow-up and collection of data on adverse events following immunisation with this vaccine during pregnancy.

37.4 Resources

• Australian Technical Advisory Group on Immunisation (2017 update) Australian Immunisation Handbook. 10th edition. Canberra: Department of Health.
• South Australian Perinatal Practice Guidelines Workgroup (2015) Rubella infection in pregnancy. In: South Australian Perinatal Practice Guidelines. Adelaide: SA Health.