Pathophysiology
Clinical meaning
Rubella is caused by the rubella virus (family Matonaviridae), typically mild in children and adults but devastatingly teratogenic when infection occurs during pregnancy, especially the first trimester. The virus is transmitted via respiratory droplets with a 14-21 day incubation period. Viremia allows placental crossing, infecting rapidly dividing fetal cells and causing congenital rubella syndrome (CRS). The classic CRS triad is sensorineural hearing loss (most common permanent defect), congenital heart defects (PDA, pulmonary artery stenosis), and eye abnormalities (cataracts, microphthalmos). First trimester infection carries >80% risk of CRS. MMR vaccination has nearly eliminated rubella in vaccinated populations, but non-immune pregnant women remain at risk.