Rubella

Epidemiology of Infectious Diseases: Rubella

Causal agent
Rubella virus, a member of the togaviridae.

Common clinical features

  • A mild viral illness. Children may develop few or no symptoms.
  • Infection with rubella among adults is characterized by mild fever, sore throat, conjunctivitis, headache, joint aches for 2-3 days followed by a maculopapular rash, which lasts about 3 days.
  • Swollen lymph glands around the ears and back of head.
  • Up to 50% of rubella infections are subclinical.
  • The main differential diagnosis is parvovirus or measles.

Complications

  • Risk of intrauterine transmission among susceptible pregnant women infected in the first trimester is  >90%, declining to 50% in the second trimester to no increased risk >20 weeks (HPA).
  • Congenital rubella infection may lead to miscarriage, stillbirth and a range of severe birth defects known as congenital rubella syndrome (CRS). These include low birth weight, cataracts, heart defects, hearing impairment, small head size and developmental delay1.

Epidemiology

  • In the UK infections with mumps peaks during the winter and spring.
  • Prior to the introduction of immunization against rubella, epidemics occurred in 6 year cycles2.
  • Laboratory confirmed cases of rubella in England and Wales declined from 2770 in 1996 to 14 in 2004 (HPA).

Reservoir
Humans

Mode of transmission
Person to person via airborne transmission or droplet spread.

Also direct contact with nasopharyngeal secretions of an infected person.

Incubation period
14-17 days, with a range of 14-21 days.

Period of Communicability
From 1 week before the onset of rash to 1 week after the onset of rash.

Prevention and control

  • Routine MMR vaccination, 2 doses at 12-15 months and at 4 years of age. There is no upper age limit and where required, two doses can be given separated by at least a one month interval. (HPA).
  • Rubella vaccine is also available as a single antigen vaccine. It is offered to previously unimmunised and seronegative post-partum women. Unless MMR is contraindicated, this may be used in place of rubella vaccine (HPA).
  • Screen all women in early pregnancy and immunize post-partum if found to be sesceptible2.
  • Laboratory diagnosis by oral fluid testing is offered by the Health Protection Agency (HPA).

References

  1. Heymann D L, editor, Control of Communicable Disease Manual. 18th ed. American Public Health Association; 2004.
     
  2. Hawker J, Begg N, Blair I, Reintjes R, Weinberg J. Communicable Disease Control Handbook, Blackwell, 2005.

© CM Kirwan 2006