The incubation period for postnatal rubella is typically 16 to18 days (range, 14 to 21 days). The mild catarrhal symptomsof the prodromal phase of rubella may go unnoticed. The characteristic signs of rubella are retroauricular, posterior cervical,and posterior occipital lymphadenopathy accompanied by anerythematous, maculopapular, discrete rash. The rash beginson the face and spreads to the body, lasting for 3 days and lessprominent than that of measles. Rose-colored spots on the softpalate, known as Forchheimer spots, develop in 20% of patientsand may appear before the rash. Other manifestations of rubellainclude mild pharyngitis, conjunctivitis, anorexia, headache,malaise, and low-grade fever. Polyarthritis, usually of the hands,may occur, especially among adult females, but usually resolveswithout sequelae. Paresthesias and tendinitis may occur.
Routine laboratory findings are nonspecific and generally do not aid in diagnosis. The white blood cell count usually is normal or low, and thrombocytopenia rarely occurs. Diagnosis is confirmed by serologic testing for IgM antibodies (typically positive 5 days after symptom onset) or by a fourfold or greater increase in specific IgG antibodies in paired acute and convalescent sera. CRS cases can have detectable IgM until 3 months of age, and stable or rising IgG titers over the first 7 to 11 months of age. False-positive IgM results can occur. Cases of suspected congenital rubella syndrome and postnatal rubella infection should be reported to the local and state health department.
The rash must be differentiated from measles, roseola, enteroviral or adenoviral infection, infectious mononucleosis, toxoplasmosis, scarlet fever, rickettsial disease, Kawasaki disease, serum sickness, and drug rash.
There is no specific therapy for rubella. Routine supportive care includes maintaining adequate hydration and antipyretics.
Other than congenital rubella syndrome (see Chapter 66) arising from rubella infection during pregnancy, complications are rare. Deaths rarely occur with rubella encephalitis.
Live rubella vaccine prevents infection and is recommended as MMR for children at 12 to 15 months and at 4 to 6 yearsof age. After vaccination, rubella virus is shed from the nasopharynx for several weeks, but it is not communicable. In children, rubella vaccine rarely is associated with adverse effects,but in postpubertal females, it causes arthralgias in 25% ofvaccinated individuals and acute arthritis-like symptoms in10% of vaccinated individuals. These symptoms typicallydevelop 1 to 3 weeks after vaccination and last 1 to 3 days.
Contraindications to rubella vaccine include immunocompromised states or an immunosuppressive course of corticosteroids (>2 mg/kg/day for >14 days); pregnancy; or recent administration of immunoglobulin (3 to 11 months, depending on dose). Vaccine virus has been recovered from fetal tissues, although no cases of CRS have been identified among infants born to women inadvertently vaccinated against rubella during pregnancy. Nevertheless women are cautioned to avoid pregnancy after receipt of rubella-containing vaccine for 28 days. All pregnant women should have prenatal serologic testing to determine their immune status to rubella, and susceptible mothers should be vaccinated after delivery and before hospital discharge.
Susceptible, nonpregnant persons exposed to rubella should receive rubella vaccination. Immunoglobulin is not recommended for postexposure prophylaxis of susceptible, pregnant women exposed to rubella.