RubellaLast Updated: January 29, 2004 Dr wesam abu mousa Coordinator dr abdalrahman abu alrob
INTRODUCTION • Rubella is usually a mild viral illness involving the skin, the lymph nodes, and, less commonly, the joints. Its most important complication is congenital rubella syndrome (CRS).
Pathophysiology: • Rubella is an RNA virus classified as a Rubivirus in the Togaviridae family. • Frequency: • In the US: 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 vaccine, the number of cases has decreased by approximately 99%.
Mortality/Morbidity: • Rubella is usually mild. Rarely, encephalitis, thrombocytopenia, or neuritis may occur. Such manifestations are usually self-limited. • Sex: Both sexes are equally affected. • Age: Rubella is a disease primarily affecting young children, but adolescents and young adults are also affected.
History • Studies on children shortly after the isolation of the rubella virus, have shown that the disease is spread by nasal droplet infection and has an incubation period of 14-19 days, with onset of a rash usually on the 15th day. The disease can be spread from a few days before to 5-7 days after the appearance of the exanthem.
The virus can be detected in the pharynx from 7 days before until 7 days after the rash. A viremia was detected from 7 days before until the day of the rash, and the virus was present in the stool from 4 days before until 4 days after the rash. Isolating the virus from children with subclinical infections was also possible.
Patients are most contagious when the rash is erupting. Rarely, the virus may be shed from the pharynx up to 15 days after the appearance of the rash, in rapidly diminishing amounts, and it is very difficult to detect by culture after 5-7 days. Patients are not considered clinically contagious after 7 days. • Infection usually confers lifelong immunity, but reinfection is occasionally detected serologically after the natural disease or a vaccination upon reexposure to the virus and rarely results in clinical disease.
Physical • In children, a prodrome may not be present. The rash may be the first manifestation. In adults, fever, sore throat, and rhinitis may be present. The exanthem begins as discrete macules on the face that spread to the neck, the trunk, and the extremities. The macules may coalesce on the trunk. Appearance of the rash corresponds with the appearance of the rubella-specific antibody.
The exanthem lasts 1-3 days, first leaving the face, and may be followed by desquamation. On occasion, a nonspecific enanthem (Forscheimer spots) of pinpoint red macules and petechiae can be seen over the soft palate and the uvula just before or with the exanthem.
The hallmark of rubella is the generalized, tender lymphadenopathy that involves all nodes, but which is most striking in the suboccipital, postauricular, and anterior and posterior cervical nodes. It is most prevalent at the time of appearance of the exanthem but may precede it by a week. The tenderness that accompanies this lymphadenopathy subsides rapidly; however, the enlargement may last days or weeks.
in adults, polyarthralgia and even polyarthritis may occur and rarely may persist longer than 2 weeks. It may resemble rheumatic fever or rheumatoid arthritis with small and large joints being involved bilaterally with or without swelling. The swelling can be very marked. 10% have arthritis, 3 days post rash with the natural infection or within 2-6 weeks after a vaccination.
Rarely, recurrent episodes of inflammation of the fingers, the wrists, and the knees can continue for more than a year. Very rarely, a syndrome of low-grade fever, chronic fatigue, and myalgias can persist for months or years. The pathogenesis of the arthritis is not known. It may be related to the presence of circulating immune complexes, which are seen more frequently in persons who have had vaccinations with joint complaints than those who have had vaccinations but are without joint complaints.
The virus can be isolated from joint effusions in acute and recurrent cases. Peripheral blood mononuclear cells may harbor the rubella virus in chronic arthritis. Test results for rheumatoid arthritis are negative.
DIFFERENTIALS • Drug Eruptions Erythema Infectiosum (Fifth Disease) Measles, Rubeola Mucocutaneous Lymph Node Syndrome (Kawasaki Disease) Roseola Infantum Scarlet Fever
Lab Studies • If the diagnosis is in doubt, a rising titer of immunoglobulin M (IgM) antibody over a 2-week period indicates a recent infection. • A WBC count, if performed, may be lower than normal, as in many viral infections, with increased percentages in the lymphocyte count. In those very rare cases where encephalitis is present, lymphocytes are present in the cerebrospinal fluid (CSF).
Rubella virus can be isolated from the nasopharynx, the blood, the urine, and CSF. • Now, newer tests with a higher specificity (eg, latex agglutination, fluorescence immunoassay, passive hemagglutination, hemolysis in gel, enzyme immunoassay tests) are available. From a public health standpoint, attempting to confirm a rubella infection in a pregnant woman or a newborn or an infant is important.
A pregnant woman exposed to rubella should be tested immediately for a rubella-specific antibody. The presence of rubella-specific immunoglobulin G (IgG) is evidence that the patient is immune. • If the test result is negative, repeat the test again in 3-4 weeks, and also repeat the test on the first specimen. If an antibody is present in the second test and not in the first test, an infection has occurred.
If the second test result is negative, repeat the test in 6 weeks, and, again, test it with the first specimen. A negative test result in both specimens means an infection has not occurred, whereas if the last specimen is positive and the first specimen is negative, then an infection has occurred
An infant with CRS will show the IgG antibody from the mother, which disappears in a few months and an elevated IgM antibody level because of antibody production by the infant. The presence of the IgM antibody usually indicates recent infection because IgM does not cross the placenta from the mother as does IgG
Histologic Findings: • The histopathologic features of the skin are a light perivascular infiltrate of lymphocytes with mild endothelial swelling. If petechiae or purpura are clinically present, extravasation of erythrocytes may be observed.
TREATMENT • Medical Care: No specific treatment of rubella exists. • 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.
Medication • No specific medication is available for rubella, except that given for symptomatic relief.
Prevention • The best protection against rubella and CRS is vaccination. The live rubella vaccine is a RA27/3 strain grown in human diploid cell cultures. It is usually given with the measles and mumps vaccine (MMR) at age 12-15 months and again at school entry at 4-6 years. One injection usually imparts lifelong immunity.
contraindications to vaccination exist • Pregnant women should not be vaccinated; however, vaccination of her household contacts is not contraindicated because no evidence exists that the virus would spread to her even though the vaccinee may shed the virus for 1-4 weeks. • Patients receiving immunoglobulin should avoid vaccination 2 weeks before and 3 months after immunoglobulin administration. If immunoglobulin is given, the patient should be tested for immunity at least 8 weeks following vaccination.
Patients who are seriously ill should not be vaccinated; however, fever in itself is no contraindication. • Patients with severe altered immunity should not be vaccinated. Patients on immunosuppressive therapy should not be vaccinated for 3 months. Patients with HIV may be vaccinated if they are not severely immunocompromised.
Adverse reactions to vaccination • include rash, fever, and/or lymphadenopathy developing 5-12 days later in 5-15% of children. Joint pain is rare but is more prevalent in female and is usually less severe than that seen in the naturally occurring disease. Rarely, transient peripheral neuritis symptoms have been reported.
Complication • CRS is 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% will be affected, and the severity depends on how early the infection occurs.
The most common abnormalities are ophthalmologic (eg, cataracts, retinopathy). • Cardiac abnormalities (eg, patent ductus arteriosus, pulmonary stenosis) may be seen. • Auditory involvement may be present with sensineural deafness.
Neurologic disorders (eg, meningoencephalitis, mental retardation 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.
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.
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 CRS have occurred in infants born to mothers who received immunoglobulin shortly after exposure.