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Rubella

Rubella

Causative Agent

Rubella virus

Incubation Period

  • 3 weeks

Infectious Period

Few days before until seven days after onset of rash. Infants with congenital rubella syndrome may shed the virus from their body secretions for 1 year or more after birth.

Transmission

Respiratory droplets and direct contact with nasopharyngeal secretions.

Epidemiology

Rubella immunisation was introduced in Nov 1976 for female primary school leavers at 11+ years of age. However as rubella outbreaks continued to occur in susceptible populations especially national servicemen (NS men), the vaccination was extended to cover male primary school leavers in 1982. NS men were also routinely vaccinated to eliminate rubella in army camps. The programme was further expanded to include children 1-2 years of age using the trivalent measles, mumps, rubella (MMR) vaccine in Jan 1990. The 2nd dose of MMR was introduced in 1997 for secondary and junior college students in a catch-up measles vaccination programme and to all primary school leavers in 1998. Since 2008, the 2nd dose of MMR vaccine is now given at 6-7 years of age (primary 1) under the revised National Childhood Immunisation Programme.

The rubella incidence peaked in 1996 with 487 notifications. With the catch-up measles vaccination program, the number of rubella cases has gradually declined from 10.9 cases per 100,000 population in 1999 to 3.6 per 100,000 in 2009. The incidence of congenital rubella is about 0-2 cases per year since 1995.

In a serosurveillance study of rubella conducted in 1998, it was found that the overall immunity of the population to rubella was 80.2% with the lowest immunity in the 10-14 year age group (65.5%). Another survey in 2004 showed that 15.8% of women aged 18 to 44 years were non-immune to rubella (a relatively high level compared to women of reproductive age in other developed countries).

It is important to ensure that at least 95% of the children are immunised at 1-2 years of age. Congenital rubella can only be completely eliminated if every woman in the 15-44 year age group is immunised against the disease. Women should be advised to be vaccinated before they are married and prior to conception.


  • Many cases are subclinical.
  • Infection usually starts with a mild prodrome and  appearance  of  tender  occipital, post-auricular and cervical lymphadenopathy which precedes the appearance of the rash.
  • Prodromal symptoms include low grade fever,  headache,  malaise,  anorexia, mild conjunctivitis, coryza, sore throat, cough and lymphadenopathy. The symptoms last 1 - 5 days and subside rapidly after the rash appears.
  • An enanthem consisting of reddish spots on the soft palate may be observed in  the prodromal period or on the first day of the rash but is not diagnostic.
  • The rash progresses in a cephalo-caudal direction and  usually subsides in 3  days. By the end of the first day, the body is covered with red, discrete maculopapules. By the third day, the rash disappears without any staining or desquamation.
  • The spleen may be slightly enlarged.
  • Fever if present is usually low grade and lasts 1 - 3 days.
  • Complications such as arthralgia and arthritis, which are  more  common  in adults, clear in about 5 - 10 days. Encephalitis and thrombocytopaenia are rare complications.
  • The risk of foetal infection and congenital anomalies depends on stage of pregnancy at which infection occurs (lower risk after 20 weeks).

Differential diagnoses include:

  • Exanthem subitum (Roseola infantum)
  • Drug rash
  • Infectious mononucleosis
  • Enteroviral infections
  • Mild measles
  • Scarlet fever


  • Indicate on the request form a brief clinical history, as the assays used for immunity screening and for diagnosing recent infection may differ.
  • Rubella can be diagnosed  by demonstrating a  fourfold rise in IgG antibody  titres between acute and convalescent samples and by detecting rubella-specific IgM antibody.
  • Rubella-specific IgM antibody is usually detectable by five days after onset of illness and remains detectable for at least one month but commonly for two months.
  • Caution is advised in interpretation of rubella IgM antibody tests since false positive results are not uncommon. They may arise during other virus infections such as those due to parvovirus B19, CMV or EBV.


A legally notifiable disease in Singapore. Notify Ministry of Health (Form MD 131 or electronically via CD-LENS) not later than 72 hours from the time of diagnosis.



  • Patient is managed symptomatically.
  • If infection occurs in early pregnancy, the patient should be referred to a gynaecologist or an infectious disease physician who can provide advice and counselling on the possible risks of congenital malformation and appropriate management at that point in pregnancy.
  • Patients should be isolated from non-immune persons (with droplet precautions) for seven days after onset of rash.


  • Combined measles/ mumps/rubella (MMR) vaccine is given to all pre-school children at the age 12-15 months and primary school entrants at the age of 6-7 years as part of the National Childhood Immunisation Programme (see Appendix 2).
  • Rubella vaccination is also routinely offered at polyclinics to non-immune married women and mothers who have just delivered their first babies.
  • All unimmunised children at nurseries, kindergartens and schools where an outbreak is occurring should be immunised.
  • The vaccine should be avoided in pregnancy and women who received rubella vaccine should be advised to avoid pregnancy for one month after vaccination. The observed risk for vaccine-associated congenital rubella is zero but the theoretical risk is as high as 2%. The currently recognised theoretical risk does not mandate automatic termination of pregnancy if a woman has been inadvertently vaccinated with rubella vaccine.
  • All childhood immunisations should be notified to the National Immunisation Registry, Health Promotion Board. Post-vaccination adverse reactions should also be notified to the Pharmacovigilance Branch, Health Sciences Authority.










References

  1. Committee on Epidemic Disease. Serosurveillance of rubella in Singapore. Epidemiological News Bulletin 2001; 27:1-3
  2. Ang LW, Chua LT, James L et al. Epidemiological surveillance and control of rubella in Singapore, 1991-2007. Ann Acad Med Singapore 2010; 39; 95-101





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