Congenital rubella syndrome
What is it?
It is a combination of several malformations that occur in utero due to transplacental transmission of rubella virus (congenital rubella syndrome). The risk of fetal infection is highest during the first trimester of pregnancy. The introduction of vaccination has dramatically reduced the incidence of this disease; however, there are still documented cases, and the estimated frequency is about 0.1 cases per 10,000 births (data from Istituto Superiore Sanità).
Which are the symptoms?
Rubella infection during pregnancy is not particularly problematic for the pregnant woman, but it does cause multiple neonatal defects in the fetus, including sensorineural deafness, congenital cataracts, microphthalmos, and heart disease. Brain damage usually occurs in cases of infection between the third and sixteenth weeks of pregnancy and includes microcephaly with mild to severe mental retardation, spastic diplegia, prematurity, and low birth weight. A newborn may also have rubella meningoencephalitis from birth.
How is it diagnosed?
The diagnosis is easy if there is evidence of maternal contact with rubella-infected subjects. The diagnosis should be suspected on the basis of the clinical-malformative picture documented in utero or at birth in case there is no positive anamnestic criterion. If the pregnant woman comes in contact with the infected patient a careful prenatal evaluation and diagnosis should be performed; if the woman has not been recently vaccinated, primary rubella virus infection is safe in case of:
- increased maternal blood rubella IgG levels or seroconversion with IgM found above the threshold for positivity;
- low avidity of rubella IgG;
- identification of IgM in fetal blood;
- identification of virus in amniotic fluid by gene amplification;
- presence of specific IgM in the blood of the newborn or in other samples taken from the fetus/newborn.
In the case of a positive prenatal diagnosis, complete congenital rubella syndrome is common when maternal infection occurred during the first two months of gestation. Until the twelfth week of pregnancy, about 80% of exposed fetuses are affected, while between the twelfth and sixteenth week about half of the exposed fetuses are affected. During this last period of gestation, deafness is the most common abnormality found; it seems that the other defects and growth retardation occur only after exposure during the first trimester. Congenital anomalies and growth retardation are rare after the 16th week of pregnancy.
How is it treated?
Unfortunately, the damage caused by rubella infection during the prenatal period is irreversible; for this reason, prevention is fundamental, that is, maintaining high vaccine protection rates, adhering to ministry guidelines on this matter, and reinstating vaccinations for all women of childbearing age who do not remember being infected with rubella and who were not vaccinated as children. After a typical lesion of rubella syndrome is identified, supportive therapy is carried out to minimize the manifested somatic, intellectual or cardiac disorders.
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