Mild togavirus rash illness in children and adults but devastating to the fetus when contracted in the first trimester (congenital rubella syndrome).
Also known as: German measles, 3-day measles, third disease, rubella virus, congenital rubella syndrome, CRS
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Risk factors
- Unimmunized status
- International travel and immigrant communities
- Pregnancy without documented immunity
- Healthcare workers without immunity
Pathophysiology
Virus enters via respiratory droplets, replicates in nasopharyngeal lymphoid tissue, then disseminates by viremia. In pregnancy, transplacental transmission infects the fetus; earlier gestational age confers higher risk of multiorgan teratogenesis through interference with mitotic and angiogenic processes.
Clinical presentation
Symptoms
- Prodrome (often absent in children): low-grade fever, malaise, mild coryza, sore throat 1-5 days before rash
- Tender lymphadenopathy: posterior auricular, suboccipital, posterior cervical (hallmark)
- Rash: pink to light-red maculopapular, beginning on the face and spreading rapidly to trunk and extremities; resolves in 3 days
- Polyarthralgia and polyarthritis, especially in adult women (small joints of hands, wrists, knees)
Signs / physical exam
- Forschheimer spots: petechial lesions on soft palate (suggestive but not pathognomonic)
- Tender posterior auricular and suboccipital nodes
- Mild conjunctivitis
- Joint swelling, especially metacarpophalangeal joints in adults
Classic findings
Mild pink rash with posterior auricular and suboccipital adenopathy in a postpubertal woman with new joint pain.
Differential diagnosis
- Measles — More severe prodrome, Koplik spots, slower-spreading cephalocaudal rash
- Roseola — Younger child, high fever resolves as rash appears
- Erythema infectiosum — Slapped-cheek pattern, parvovirus B19 serology
- Drug eruption — Recent new drug, eosinophilia, no posterior auricular nodes
- Scarlet fever — Strep throat, sandpaper rash, no adenopathy in the rubella distribution
- Enteroviral exanthem — Summer/fall, often with hand-foot-mouth pattern
Diagnostic workup
Diagnostic criteria
Clinical syndrome plus positive IgM or RT-PCR. Congenital rubella: positive viral isolation, RT-PCR, or persistent rubella-specific IgG beyond expected maternal antibody decline.
Labs
- Rubella IgM and IgG (paired sera) — IgM positive in acute infection
- RT-PCR on nasopharyngeal or oral swab
- Rubella IgG screening for pregnant women at first prenatal visit
- CBC: lymphocytopenia, atypical lymphocytes possible
- Report to public health (nationally notifiable)
Imaging
- Fetal ultrasound for suspected congenital rubella with growth restriction, microcephaly, cardiac defects
- Postnatal echocardiography in infants with suspected CRS (PDA, peripheral pulmonary stenosis)
Treatment
First-line
- Supportive: antipyretics, NSAIDs for arthralgia
- Droplet precautions for 7 days after rash onset
- MMR vaccine (live, 2-dose schedule) — first dose 12-15 months, second 4-6 years; women of childbearing age should be screened and vaccinated postpartum if non-immune
- MMR is contraindicated in pregnancy and should be avoided for 28 days before conception
Pregnancy exposure
- Test maternal IgG and IgM; if susceptible and exposed, monitor closely
- Counsel on CRS risk by trimester: first 12 wk highest risk (~85%); risk falls sharply after 20 wk
- Immune globulin does NOT reliably prevent fetal infection
Congenital rubella syndrome
- Multidisciplinary care: audiology, ophthalmology, cardiology, developmental specialists
- Infectious from urine for ≥1 year; contact precautions until two cultures negative
Second-line / adjunct
- Postpartum MMR for all rubella-non-immune women
- Avoid pregnancy for 28 days after MMR
Complications
- Congenital rubella syndrome: cataracts, sensorineural deafness, PDA, peripheral pulmonary stenosis, microcephaly, 'blueberry muffin' purpura, hepatosplenomegaly, intellectual disability
- Polyarthralgia/polyarthritis in adult women (usually self-limited)
- Thrombocytopenic purpura (rare)
- Encephalitis (rare)
PANCE pearls
- Posterior auricular and suboccipital lymphadenopathy is the most useful clinical discriminator from measles.
- Congenital rubella triad: cataracts, deafness, cardiac defects (PDA and peripheral pulmonary stenosis).
- Screen all pregnant women for rubella immunity at the first prenatal visit; vaccinate postpartum if non-immune.
- MMR is live attenuated — contraindicated in pregnancy; counsel 28-day delay to conception after vaccination.
- CRS infants shed virus in urine for months and require contact precautions.
References
- ACIP — CDC/ACIP Prevention of Measles, Rubella, Congenital Rubella Syndrome, and Mumps (McLean et al., MMWR Recomm Rep 2013;62(RR-04))
- AAP Red Book — American Academy of Pediatrics Red Book — Rubella chapter
- ACOG — ACOG Committee Opinion: Rubella Vaccination
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