Rubella

Question 1

What is the rate of rubella transmission and the risk of congenital defects at 
>12/40
13-16 weeks
17-22
23-30
31-36
36+

Answer 1

1-12 /40 fetal infection 80% congenital defects 85%
13-16/40 fetal infection 54% congenital defects 35%
17-22/40 fetal infection 36% congenital defects rare
23-30/40 fetal infection 30% congenital defects rare
31-36/40 fetal infection 60% congenital defects rare
36+ fetal infection 100% congenital defects rare

• Consider termination of pregnancy if maternal infection in first trimester.
• If maternal infection occurred in second trimester, consider fetal testing.
• Maternal infection after 20 weeks is rarely associated with CRS

Question 2

How is rubella transmitted

Answer 2

Transmitted by droplet contract from nasopharyngeal infections
Replicates in the lymphatic tissue and spreads haematolgenously

Question 3

Prevention

Answer 3

Routine antenatal screening IgG only

Pre preg vaccination

Question 4

Maternal presentation of rubella

Answer 4

Mild self limiting illness
Characteristic exanthem
Sx 14-21 days after inoculation
50% asymptomatic
Mild prodromal syndrome 1-5 days

Question 5

Fetal consequences of maternal rubella infection

Answer 5

At birth or early manifestations
• Deafness (sensory neural hearing loss, 60–75%), central nervous system dysfunction (10–25%, mental retardation, developmental delay, microcephaly), cardiovascular defects (10–20%, patent ductus, pulmonary artery stenosis, pulmonary stenosis), ophthalmological abnormalities (10–25%, cataracts, micropthalmos, retinopathy, glaucoma, strabismus, cloudy cornea),
Others: growth retardation, haematological abnormalities, GI tract abnormalities, pneumonitis & osteitis.

Late manifestations • Deafness (sensory neural hearing loss), neurological deficiencies, epilepsy, cataracts, retinopathy, tooth defects, growth retardation, insulin dependent diabetes mellitus (up to 50 times the rate in the general population), thyroid dysfunction and panencephalitis.

Question 6

Maternal management of infection

Answer 6

No specific management of mother (rubella specific immunoglobulin is not effective as post-exposure prophylaxis and normal human immunoglobulin not indicated).

Question 7

Pregnancy management for rubella

Answer 7

Rubella PCR, rubella culture and fetal IgM can be performed following chorionic villus sampling (CVS) or amniocentesis.
Prenatal testing is recommended at least 6 weeks after known maternal infection is and best performed after the 20th week of gestation
• CVS is associated with risk of contamination with maternal tissue giving false +ve PCR.
• PCR is not widely available and sensitivity is generally not well validated. However, a positive result will be helpful (assuming that contamination can be excluded). • False negative fetal IgM is common until late in pregnancy.

Question 8

Management

Answer 8

No specific management • Breast feeding not contraindicated
• Ensure ophthalmology, cardiac and hearing assessments at birth
• Regular assessments (3 to 6 monthly) necessary in the first few months and years of life to detect the emergence of late abnormalities related to persisting infection*
• Infants are infectious for at least 12 months after birth and a potential infection risk to susceptible female staff and pregnant contacts
• Infant should be isolated (droplet and contact) while in hospital • Ensure all hospital contacts/caregivers are rubella immune