Rubella (German measles)
Overview
•Incubation: 14-21 days; up to 50% subclinical
•Prodrome (1-5 days): low-grade fever, malaise, mild URTI, conjunctivitis
•Suboccipital and postauricular lymphadenopathy - highly characteristic, often precedes rash
•Rash - pink-red discrete maculopapular, starts on face, spreads cephalocaudally to trunk and limbs; fades within 3 days (unlike measles)
•Forchheimer spots - petechiae on soft palate; supportive but not pathognomonic
•Arthralgia/arthritis - more common in adult women; small joints of hands and wrists
•Fever - usually mild (37.5-38.5°C), unlike the high fever of measles
•Infectious period: 7 days before rash to 7 days after rash onset
Investigations
🥇 First-line
•rubella-specific IgM and IgG serology - IgM indicates acute infection (detectable from rash onset for up to 8 weeks)
•throat swab or nasopharyngeal swab for rubella PCR - most sensitive in early infection
•Urine for rubella PCR - increases diagnostic yield
🏆 Gold standard
•rubella IgM serology with PCR confirmation
•All suspected cases must be notified to the local Health Protection Team (HPT) - same-day referral in pregnancy
Differential diagnosis
Management
•Postnatal rubella (child/non-pregnant adult): supportive - paracetamol or ibuprofen for fever and arthralgia; no antiviral therapy
•Isolation: exclude from school/work for 5 days from rash onset; avoid contact with pregnant women
•Confirmed maternal infection: urgent referral to obstetrics and fetal medicine; counsel re CRS risk by gestational age; offer amniocentesis for rubella PCR; discuss termination if first trimester
•Non-immune pregnant woman exposed to rubella: test urgently for IgM and IgG; normal human immunoglobulin does NOT reliably prevent infection or CRS - not routinely recommended
•Post-partum: non-immune women identified at antenatal screening should receive MMR vaccine postnatally before discharge
Prevention
•MMR vaccine - two doses required for reliable immunity
•First dose: 12-13 months; second dose: 3 years 4 months (pre-school booster)
•Antenatal screening: all pregnant women offered rubella immunity testing at booking; non-immune offered MMR postnatally
Congenital rubella syndrome (CRS)
•Risk of CRS depends on gestational age at infection - first trimester ~90% risk
•Classic triad: sensorineural deafness (most common), congenital cataracts, congenital heart disease (PDA or pulmonary artery stenosis)
•Additional features: microcephaly, intellectual disability, IUGR, thrombocytopenic purpura ('blueberry muffin'), hepatosplenomegaly, retinopathy