Rubella (German measles)

• is usually a mild illness, with a fever, rash and swollen lymph glands.
• if contracted by pregnant women during the first 10 weeks of pregnancy, the disease can cause life-long problems for babies

• Mode of transmission
  • droplet infection
  • direct contact with nasopharyngeal secretions of infectious cases.
• Timeline
  • incubation period is 14 to 17 days, up to 21 days.
  • communicable for about 7 days before and at least 4 days after rash onset.
  • Infants with congenital rubella syndrome may shed the virus for months after birth

• Clinical presentation
  • mild febrile illness
  • diffuse punctate and maculopapular rash
  • The rash typically starts on the face, becoming generalised over 24 hours and lasts 3 days.
  • Cervical lymphadenopathy (typically posterior auricular, posterior cervical and suboccipital lymph nodes) is characteristic and precedes the rash by 5 to 10 days.
  • Asymptomatic infection is common.
  • Children usually present with few or no constitutional symptoms
  • Adolescents and Adults
    • may have a 1 to 5 day prodrome of low-grade fever, headache, malaise, anorexia, mild coryza and conjunctivitis.
    • may develop transient polyarthralgia of fingers, wrists and knees. Encephalitis and thromobocytopenia are rare complications.
  • Infection in pregnancy can result in
    • congenital rubella syndrome
      • risk of CRS is up to 90% if maternal infection occurs during the first 10 weeks of gestation.
      • Defects are rare when maternal infection occurs after the 20th week of gestation.
    • miscarriage
    • stillbirth

• Contact Management
  • Identification of contacts
    • Direct contact with respiratory secretions from the case is generally considered significant.
    • Contacts include
      • people living in the same household, or who are in the same class, at the same social function, or work in the same area as the case

• Treatment
  • Passive Immunisation
    • Immunoglobulin given after exposure to an infectious case is not effective in preventing rubella infection.
  • Active Immunisation
    • MMR should be offered to susceptible contacts if they have no contraindications to vaccination.
    • MMR will not avert disease in those already infected and incubating infection, it may be effective in preventing subsequent infection if there is likely to be ongoing exposure.
    • All pregnant women with exposure to an infectious case should be offered urgent serological testing, irrespective of their history of previous vaccination, or history of past clinical infection or a positive rubella antibody result

Rubella reinfection

• Numerous cases of congenital rubella syndrome due to rubella reinfection have been reported.
• All involved exposure to rubella in the first trimester of pregnancy after both natural and vaccine-induced immunity, usually with subclinical infection in the mother.
• The immune response may involve more than humoral immunity, but it is clear that rubella antibodies decline over time and may increase the risk of reinfection.
  • In a study involving Korean children, 18.8% of those who had been vaccinated and 13.8% of those with natural immunity were found to be seronegative for rubella virus after 3 years.
  • An Italian study showed that 9.8% of vaccinated girls were reinfected by wild-type rubella virus within 5 years.
• Prenatal serologic testing
  • rubella usually includes only the IgG titre, and the result is reported as “immune” or “nonimmune”
  • There is controversy over what level of titre confers immunity
    • there were mothers with congenital rubella syndrome had rubella IgG titres of at least 15 IU/mL at the start of pregnancy, a level considered to be protective (Bullens D, Smets K, Vanhaesebrouck P. Congenital rubella syndrome after maternal reinfection. Clin Pediatr 2000;39(2):113-6)
    • ? current cutoff level 10– 15 IU/mL is too low to be considered protective and whether women with low positive rubella titres before pregnancy might benefit from repeat vaccination
    • single IgG titre without an IgM titre cannot differentiate recent infection from immunity
      • Rubella-specific IgM titres could be routinely measured during the prenatal screening, but the cost-effectiveness of this approach would be questionable.

Congenital rubella syndrome despite maternal antibodies = Anna Banerji, Elizabeth Lee Ford-Jones, Edmond Kelly and Joan Louise Robinson, CMAJ June 21, 2005 172 (13) 1678-1679; DOI: https://doi.org/10.1503/cmaj.050230

Congenital rubella syndrome

Classic Triad

• hearing impairment
• congenital heart defects – pulmonary artery stenosis and patent ductus arteriosus
• eye anomalies – cataracts, pigmentary retinopathy or congenital glaucoma

Congenital rubella syndrome is characterised by:

• ophthalmological:
  • cataracts
  • pigmentary retinopathy
  • microphthalmos
  • congenital glaucoma
• auditory:
  • sensorineural hearing impairment
• neurological:
  • behavioural disorders
  • meningoencephalitis
  • microcephaly
  • developmental delay.
• cardiac:
  • patent ductus arteriosus
  • pulmonary artery stenosis
• other:
  • growth retardation
  • interstitial pneumonitis
  • radiolucent bone disease
  • hepatosplenomegaly
  • thrombocytopenia

Rubella (non-congenital)

	lab definitive evidence	lab suggestive evidence	clinical evidence
Confirmed case	Isolation of rubella virus OR De​tection of rubella virus by nucleic acid testing OR IgG seroconversion or a significant increase in antibody level ( 4x rise in levels) except  – If the case has received a rubella-containing vaccine 8days to 8weeks before testing.	-not needed-	-not needed-
Probable case​	————-	Detection of rubella-specific IgM antibody – except If the case has received a rubella-containing vaccine 8days to 8weeks before testing.	A generalised maculopapular rash and Fever and Arthralgia/arthritis OR lymphadenopathy OR conjunctivitis

Congenital Rubella Infection (CRI)

is reported based on relevant evidence from a live or stillborn infant, miscarriage or pregnancy termination

A confirmed case (CRI) requires either:

• laboratory definitive evidence (fetal); or
• laboratory definitive evidence (infant) and epidemiological evidence

A probable case (CRI) requires either:

• epidemiological evidence (1st trimester infection), or
• epidemiological evidence (2nd and 3rd trimester infection) and laboratory suggestive evidence (infant)

	lab definitive evidence (fetal)	lab definitive evidence (infant)	epidemiological evidence
confirmed case (CRI)	Isolation or detection of rubella virus from clinical sample fetal blood or tissue, amniotic fluid, chorionic villus sample by culture or nucleic acid testing	Isolation or detection of rubella virus from an appropriate clinical sample in an infant or detection of rubella-specific IgM antibody in the serum of the infant.	The mother has confirmed rubella infection during pregnancy
probable case (CRI)	–	–	Epidemiological evidence (1st trimester infection) or Epidemiological evidence (2nd and 3rd trimester infection) and laboratory suggestive evidence (infant) – (High / rising rubella-specific IgG level in first year of life)

Congenital Rubella Syndrome (CRS)

A confirmed case (CRS) requires:

• Laboratory definitive evidence (fetal or infant CRI), as described above, and
• clinical evidence.

Clinical evidence (CRS)

A live or stillborn infant with any of the following compatible defects:

• cataract, congenital glaucoma, congenital heart disease, hearing defect, microcephaly, pigmentary retinopathy, developmental delay or
• purpura, hepatosplenomegaly, meningoencephalitis, radiolucent bone disease or
• other defect not better explained by an alternative diagnosis.

A probable case (CRS) requires:

• Laboratory suggestive evidence (infant) or epidemiological evidence (as for CRI case as described above), and ​
• Clinical evidence (as for confirmed CRS case).​