(German Measles; 3-Day Measles)
(See also Congenital Rubella.)
Rubella is a contagious viral infection that may cause adenopathy, rash, and sometimes constitutional symptoms, which are usually mild and brief. Infection during early pregnancy can cause spontaneous abortion, stillbirth, or congenital defects. Diagnosis is usually clinical. Cases are reported to public health authorities. Treatment is usually unnecessary. Vaccination is effective for prevention.
Rubella is caused by an RNA virus, rubella virus, which is spread by respiratory droplets through close contact or through the air. Patients can transmit rubella during asymptomatic infection or from 7 days before the rash appears until 15 days after onset of the rash; the period of greatest risk is from a few days before the rash appears to 7 days after onset of the rash. Congenitally infected infants (see Congenital Rubella) may transmit rubella for many months after birth.
Rubella is less contagious than measles. Immunity appears to be lifelong after natural infection. However, in unvaccinated populations, 10 to 15% of young adults have not had childhood infection and are susceptible. At present, incidence in the US is at a historic low because of routine childhood vaccination; all cases since 2004 have been linked to importation.
Many cases are mild. After a 14- to 21-day incubation period, a 1- to 5-day prodrome, usually consisting of low-grade fever, malaise, conjunctivitis, and lymphadenopathy, occurs in adults but may be minimal or absent in children. Tender swelling of the suboccipital, postauricular, and posterior cervical nodes is characteristic. There is pharyngeal injection at the onset.
The rash is similar to that of measles but is less extensive and more evanescent; it is often the first sign in children. It begins on the face and neck and quickly spreads to the trunk and extremities. At onset, a blanching, macular erythema may appear, particularly on the face. On the 2nd day, the rash often becomes more scarlatiniform (pinpoint) with a reddish flush. Petechiae form on the soft palate (Forschheimer spots), later coalescing into a red blush. The rash lasts 3 to 5 days.
Constitutional symptoms in children are absent or mild and may include malaise and occasional arthralgias. Adults usually have few or no constitutional symptoms but occasionally have fever, malaise, headache, stiff joints, transient arthritis, and mild rhinitis. Fever typically resolves by the 2nd day of the rash.
Encephalitis has occurred rarely during large military outbreaks. Complete resolution is typical, but encephalitis is occasionally fatal. Thrombocytopenic purpura and otitis media occur rarely.
Rubella is suspected in patients with characteristic adenopathy and rash. Laboratory diagnosis is necessary for pregnant women, patients with encephalitis, and neonates. Also, laboratory evaluation is strongly encouraged for all suspected cases of rubella for public health purposes. A ≥ 4-fold rise between acute and convalescent (4 to 8 wk) antibody titers confirms the diagnosis, as can serum rubella IgM antibody testing. Detection of viral RNA by reverse transcription–PCR of throat, nasal, or urine specimens may also be done to confirm the diagnosis; genotype analysis is useful in epidemiologic investigations.
Differential diagnosis includes measles (see Measles), scarlet fever (see Streptococcal Infections : Scarlet fever), secondary syphilis (see Syphilis : Secondary syphilis), drug rashes, erythema infectiosum (see Erythema Infectiosum), and infectious mononucleosis (see Infectious Mononucleosis) as well as echovirus and coxsackievirus infections (see Table: Some Respiratory Viruses). Infections with enteroviruses and parvovirus B19 (erythema infectiosum) may be clinically indistinguishable.
Some of these conditions can be distinguished from rubella as follows:
Measles: Rubella is differentiated from measles by the milder, more evanescent rash, milder and briefer constitutional symptoms, and absence of Koplik spots, photophobia, and cough.
Scarlet fever: Within a day of onset, scarlet fever usually causes more severe constitutional symptoms and pharyngitis than does rubella.
Secondary syphilis: In secondary syphilis, adenopathy is not tender, and the rash is usually prominent on the palms and soles. Also, laboratory diagnosis of syphilis is usually readily available.
Infectious mononucleosis: Infectious mononucleosis can be differentiated by its more severe pharyngitis, more prolonged malaise, and atypical lymphocytosis and with Epstein-Barr virus antibody testing (see Infectious Mononucleosis).
Live-virus vaccine is given routinely (see Table: Recommended Immunization Schedule for Ages 0–6 yr and Recommended Immunization Schedule for Ages 7–18 yr). It produces immunity for ≥ 15 yr in > 95% of recipients and does not appear to transmit the infection. Because certain other infections are clinically indistinguishable from rubella, a reported history of rubella does not guarantee immunity.
Vaccination is given to children as a combined measles, mumps, and rubella vaccine in 2 doses:
One dose is recommended for all susceptible postpubertal people, especially college students, military recruits, health care practitioners, recent immigrants, and people working with young children. Routine vaccination is recommended for all susceptible mothers immediately after delivery. Screening women of childbearing age for rubella antibodies and immunizing those susceptible are also suggested. However, women receiving the vaccine should prevent conception for at least 28 days afterward. The vaccine virus may be capable of infecting a fetus during early pregnancy. The vaccine does not cause congenital rubella syndrome, but risk of fetal damage is estimated at ≤ 3%. Vaccine use is contraindicated throughout pregnancy.
Fever, rash, lymphadenopathy, polyneuropathy, arthralgia, and arthritis occur rarely after vaccination in children; painful joint swelling occasionally follows vaccination in adults, usually in nonimmune women.
Rubella causes a scarlatiniform rash and often low-grade fever, malaise, conjunctivitis, and lymphadenopathy (characteristically involving the suboccipital, postauricular, and posterior cervical nodes).
Most cases are mild and complications are few except for rare cases of encephalitis and the risk during early pregnancy that infection can cause spontaneous abortion, stillbirth, or congenital defects.
Laboratory diagnosis is strongly encouraged for all suspected cases for public health purposes; serologic or PCR testing can be done.
Screen women of childbearing age for rubella antibodies and immunize those susceptible, providing conception is prevented for ≥ 28 days afterwards.
Vaccination is contraindicated during pregnancy.