Last reviewed 07/2021

Rubella a mild illness caused by infection with rubivirus, an RNA togavirus. Spread of the virus is by droplets from the respiratory tract.

The only known hosts are humans (2). Individuals with rubella are most infectious during the eruption of the rash but the infectious period may vary from 7 days before to 4 days after the onset of the rash (1).

The true importance of rubella is the teratogenicity of the virus during the first trimester of pregnancy, resulting in fetal loss or congenital rubella syndrome (CRS). The risk of intrauterine transmission causing fetal damage varies with the gestational stage:

  • if <11 weeks – fetal damage in up to 90% of surviving infants, multiple defects can be seen
  • 11-16 weeks – the risk declines to about 20%
  • 16-20 weeks – fetal damage is rare, but there is a minimal risk of deafness
  • >20 weeks - no increased risk (1,3)

It is for this reason that there is an extensive immunisation program in the UK. Note that from October 2003, sero-negative women of child-bearing age and health workers who require protection against rubella are to be offered the combined measles-mumps-rubella (MMR) vaccine (4).

It is a notifiable disease in UK (2).

Click here for an example image of rubella rash