Rubella (German measles)
Rubella is typically a mild viral illness characterized by fever, rash, and lymphadenopathy. However, maternal infection during early pregnancy poses significant risks to the fetus.
Mode of Transmission
- Droplet infection
- Direct contact with nasopharyngeal secretions from infectious individuals
Timeline
- Incubation Period: Usually 14–17 days (range up to 21 days)
- Infectious Period: Approximately 7 days before to at least 4 days after rash onset
- Infants with congenital rubella syndrome (CRS) may shed the virus for months after birth
Clinical Presentation
- General Symptoms:
- Mild fever
- Diffuse punctate and maculopapular rash starting on the face, generalizing within 24 hours, lasting about 3 days
- Characteristic cervical lymphadenopathy (posterior auricular, posterior cervical, suboccipital nodes), occurring 5–10 days before rash onset
- Often asymptomatic, particularly in children
- Adolescents and Adults:
- Prodrome lasting 1–5 days: low-grade fever, headache, malaise, anorexia, mild coryza, conjunctivitis
- Possible transient polyarthralgia affecting fingers, wrists, knees
- Rare complications include encephalitis and thrombocytopenia
Infection in Pregnancy
- Risks:
- Congenital Rubella Syndrome (CRS): Up to 90% risk if infection occurs within the first 10 weeks of gestation; rare after the 20th week
- Miscarriage
- Stillbirth
Contact Management
- Identification of Contacts:
- Significant exposure includes direct contact with respiratory secretions
- Includes household members, classmates, social contacts, or workplace colleagues
- Passive Immunisation:
- Immunoglobulin post-exposure is ineffective
- Active Immunisation:
- MMR vaccine should be offered promptly to susceptible contacts without vaccination contraindications
- MMR is ineffective if already infected but may protect against ongoing or future exposures
- Pregnant Women:
- Urgent serological testing is recommended for all pregnant women exposed, regardless of prior vaccination, clinical infection history, or previous serological immunity
Rubella Reinfection
- Documented cases of CRS from maternal reinfection exist, usually from exposure in the first trimester after prior natural or vaccine-induced immunity
- Immunity wanes over time, increasing reinfection risks
- Studies demonstrate significant seronegative rates 3–5 years post-immunization or natural infection
- 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
- Routine prenatal rubella testing typically measures IgG titres to determine immunity status
- Controversy exists regarding the protective threshold level (currently 10–15 IU/mL)
- Cases of CRS have occurred despite titres ≥15 IU/mL, questioning current protective cut-off
- Single IgG titre without IgM measurement cannot differentiate between recent infection and immunity
- Routine IgM testing during prenatal screening remains controversial due to uncertain cost-effectiveness
Congenital rubella syndrome
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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 Detection 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).