Practice Essentials
Rubella, commonly called German measles, is usually a mild viral illness involving the skin, the lymph nodes, and, less commonly, the joints. The most important complication of rubella is congenital rubella syndrome (CRS).
Also see Pediatric Rubella and Pediatric Rubella in Emergency Medicine.
Pathophysiology
Rubella is a single-stranded RNA virus classified as the only member of the genus Rubivirus in the Togaviridae family. The virus is not particularly environmentally robust and can be easily killed with detergent, ultraviolet light, pH extremes, and temperatures greater than 56°C. Rubella virus has an outer envelope which contains E1 and E2, glycosylated lipoproteins that form transmembrane spikes. These glycosylated lipoproteins are responsible for activating the humoral response. The E1 protein contains the antigenic determinants that induce major immune responses, while the E2 protein's role is relegated to forming connections between rows of E1 proteins. [1]
Prognosis
The prognosis is usually excellent, with the exception of CRS.
Complications
Complications are rare with rubella in healthy infants and adults. Rarely, encephalitis or peripheral neuritis may occur; however, recovery is usually complete without sequelae. Thrombocytopenia usually resolves within a month, but it may result in purpura, epistaxis, and intestinal bleeding.
Congenital rubella syndrome (CRS)
This the most severe and important complication of rubella and occurs in the fetus of a pregnant woman without immunity to the virus. Of infants infected in the first trimester, 50% are affected, and the severity depends on how early the infection occurs. Note the following:
The most common abnormalities are ophthalmologic in nature (eg, cataracts, retinopathy).
Cardiac abnormalities (eg, patent ductus arteriosus, pulmonary stenosis) may be seen.
Auditory involvement may be present as sensorineural deafness.
Neurologic disorders (eg, meningoencephalitis, intellectual disability with behavioral disorders) may occur.
If infection occurs after organ development, a variable picture may be seen, with hepatitis, splenomegaly, pneumonitis, myocarditis, and/or osteomyelitis.
If the bone marrow is affected, thrombocytopenia with purpura and petechiae occur. Bizarre purple macules and papules, which represent persistent dermal (extramedullary) hematopoiesis, are seen in the skin. This appearance is known as blueberry muffin baby. Note the image below.
An infant who is affected may continue to shed the virus for up to 1 year. At least 85% of infants who are affected shed the virus at 1 month, and 1-3% do so at 1 year. Therefore, these individuals should be considered contagious for at least 1 year and should be considered an exposure threat to nonimmune pregnant women, unless nasopharyngeal or urine culture results are repeatedly negative.
Pregnancy
No adequate treatment is available for pregnant women exposed to rubella. Immunoglobulin is not recommended unless termination of the pregnancy is not an option because cases of congenital rubella syndrome have occurred in infants born to mothers who received immunoglobulin shortly after exposure.
Diagnostics
The histopathologic features of the skin are those of the Togaviruses, namely, a light perivascular infiltrate of lymphocytes with mild endothelial swelling. If petechiae or purpura are present clinically, extravasation of erythrocytes may be observed.
Also see Laboratory Studies.
Treatment
No specific treatment is available for rubella. The disease is usually self-limited. Rest and oral fluids are appropriate. Individuals may remain contagious for 7 days after the onset of the rash, and they should be appropriately isolated from work, school, or other public settings.
Also see Prevention and Medication.
Epidemiology
Frequency
Before the live rubella vaccine, epidemics of the disease were seen in young children (most common), adolescents, and young adults every 5-9 years in winter and early spring. Since the rubella vaccine, the number of rubella cases has decreased significantly.
Because of the morbidity of measles and rubella, the World Health Organization (WHO) maintains a worldwide Measles and Rubella Laboratory Network (LabNet) to monitor the behavior of the viruses. [2] Because of the unreliability of clinical diagnosis, laboratory surveillance is important in setting rubella elimination goals. Serum-based diagnostics remain the criterion standard; however, programs are being developed using dried blood samples and oral fluid for confirmation of infection in those areas where patients might resist venipuncture or where transportation and refrigeration of blood samples is difficult.
One major focus of infection in the recent past was unvaccinated adults. [3] Of concern was the high incidence of rubella in unvaccinated Hispanic immigrants and congenital rubella syndrome in their offspring. [4] Individuals from Columbia, the Dominican Republic, and Central America, where vaccination programs were just starting, were often susceptible to rubella. In one study, 44% of congenital rubella syndrome cases were in Hispanic infants. [5] This was a public health concern. In an outbreak in 1997-98 in New York State, the infections spread from the Hispanic community, along train and work lines, to involve 14 towns and 95 individuals.
Now fortunately, the Pan American Health Organization of the WHO announced that the endemic transmission of rubella has ended in the Americas and that the Americas are free of endemic rubella. [6] The last confirmed case was in Argentina in 2009. This end of endemic rubella was achieved by the high percentage of vaccination in the population. This does not mean that the threat of rubella is over, as the remainder of the world is not rubella–free, and, with the mobility of the world population, cases of rubella may still enter the United States.
The Centers for Disease Control and Prevention (CDC) [7] states that a nonimmune woman with a rubella infection in the first trimester stands a 90% chance of miscarriage, stillbirth, or transmittal of congenital rubella syndrome (CRS) to her baby. Five of 10 healthy babies do not receive the vaccine, even though it now costs about a dollar. The CDC maintains that 79 countries now are using the vaccine more, but the WHO [8] maintains that 45 member states have not yet introduced the vaccine and two regions (African and Eastern Mediterranean) have not yet set control targets. Therefore, it is possible for rubella to enter the United States, and so it is essential to maintain a high level of immunization in the population to ensure herd immunity. Constant vigilance remains crucial.
Race-, sex-, and age-related information
Rubella has no racial predilection. Both sexes are equally affected by rubella. Rubella primarily affects young children, but adolescents and young adults are also affected.
Patient Education
Now that endemic rubella is eliminated in the Americas, the threat of rubella epidemics and subsequent congenital rubella syndrome would be from cases of rubella that enter the United States from other areas of the world and infect the unvaccinated clusters in this country. Therefore, the Measles and Rubella Initiative calls for monitoring the disease using effective surveillance, developing and maintaining outbreak preparedness, communicating and engaging to build public confidence and demand for immunization, and continuing research to improve cost-effective vaccinations and diagnostic tools. [9]
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Young adult with macular rash.
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Child with generalized eruption.
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Blueberry muffin newborn with lesions on the forehead.
