Congenital rubella is a syndrome that occurs when a fetus has been infected with the rubella virus while in the uterus. It is primarily characterized by abnormalities of the heart and nervous system, the eyes and the ears. The fetus is most vulnerable to the virus during the first three months of pregnancy, although pregnant women are advised to avoid exposure to rubella virus at all times. Women who contract rubella during pregnancy have a high risk of having a baby with congenital rubella.
Classic congenital rubella syndrome symptoms include a combination of heart, eye and hearing defects, although infection and damage can occur in almost every organ system. Of the abnormalities most likely to be present at birth, cardiovascular defects are most common, such as underdevelopment (hypoplasia) of the pulmonary artery and the failure of a duct connecting the pulmonary artery and aorta (patent ductus arteriosus) to close.
Low birth weight, inflammation of the bones (osteitis), enlarged liver and spleen (hepatosplenomegaly), disease of the retina (retinopathy), and cataracts of the crystalline lens of the eye also occur frequently. Brain infection (encephalitis), an abnormally small head (microcephaly), swollen lymph glands (adenopathy), inflammation of the lungs (pneumonitis), jaundice, reduced number of blood platelets (thrombocytopenia), pinpoint purplish red spots due to bleeding in the skin (petechiae) or purpura, and anemia may also occur in babies with this syndrome.
Congenital rubella syndrome can be viewed as a chronic infection that may produce progressive damage. Central nervous system abnormalities such as hearing loss, mental retardation, behavior problems and slowness in muscular development, are frequent and significant clinical problems.
Most patients who are symptomatic, and many of those who lack signs of infection at birth, will develop some degree of hearing loss or psychomotor damage during early childhood.
Congenital rubella can affect a fetus when a pregnant woman who is not immune to the virus contracts rubella (German Measles). The baby may also be affected if the mother contracts rubella immediately before conception. The fetus is most vulnerable during the first three months (first trimester) of a pregnancy.
Congenital rubella is found in newborns and infants of mothers who were infected with rubella immediately before or during the early months of pregnancy. The frequency of congenital rubella thus depends upon the number of women of childbearing age who are susceptible to the virus, and the frequency of rubella infection in the community. Before the development of rubella virus vaccine, epidemics of rubella and congenital rubella occurred about every six to nine years. During epidemic years, congenital rubella infection was found (using serologic testing to identify nonsymptomatic cases) in as many as 2% of newborns; the rate of its presence at other times (the endemic rate) is 0.1%. Widespread use of rubella vaccine in the United States has eliminated epidemics, but the endemic rate of congenital infection appears to be about the same.
Both the chance of transmission of rubella to the fetus during pregnancy and the consequences of the infection to the unborn baby are related to the stage of development of the fetus at the time of maternal infection. Maternal infection during the first 8 weeks of pregnancy results in an infection rate in the fetus of about 85%. Subsequently, the rate of transmission drops sharply so that the risk of fetal infection is 50% when the mother is infected during the 12th week of pregnancy, 15% during weeks 13 to 20, and approaching zero after the 20th week of pregnancy.
There is no treatment for maternal rubella or congenital rubella syndrome. Therefore, prevention assumes paramount importance. It is most important to immunize all children, in an attempt to prevent epidemics. Children should receive rubella immunization at 15 months of age, along with mumps and measles in a combined vaccine. Many authorities now recommend that a repeat rubella immunization be given to 10-year-olds, because vaccine-induced immunity may not persist as long as naturally acquired immunity.
Women of childbearing age who are susceptible to rubella (a serum test can establish the presence of the rubella-antibody in their blood) should also be vaccinated. Until recently, the Centers for Disease Control and Prevention (CDC) recommended that a woman should wait for three months after vaccination against rubella before getting pregnant. The CDC has now (2004) reduced that period to 28 days.
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FROM THE INTERNET
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