Rubella

Abstract

Rubella is associated with an 80% risk of congenital abnormalities if acquired in the first 12 weeks of pregnancy. Reinfection in early pregnancy presents a much smaller risk. Prenatal diagnosis may be useful to assess the risk to the fetus. Congenital rubella is a progressive disease and some abnormalities will not be present at birth. Rubella and congenital rubella are usually diagnosed by detection of rubella-specific IgM; it may be difficult to confirm a diagnosis of congenital rubella in children over 3 months of age. Rubella vaccines are usually combined with measles and mumps vaccines. Their use has enabled some industrialised countries to eliminate rubella and congenital rubella. Countries should ensure that susceptible women of child-bearing age and health care workers are offered a rubella-containing vaccine. Rubella vaccine is contraindicated during pregnancy, but if a pregnant woman is inadvertently vaccinated it is not an indication for termination or prenatal diagnosis.

Prenatal diagnosis of congenital rubella infection in São Paulo

“…Rubella is slower than in postnatal infection and low avidity can be detected for a longer period. 2,3,16 The present study confirms the above findings by means of IgM negative in the sera of the four newborns infected. However, these newborns that had no detectable IgM were positive for RV RNA by PCR assays.…”

“…The rash is not very specific or particularly apparent, and most infectious cases are subclinical. 2,3 Therefore, demonstration of seroconversion and presence of high IgM titers is the primary mode of diagnosis of acute rubella in pregnancy. Unfortunately, booking serum samples are often not available.…”

“…It can be used in conjunction with serology for the diagnosis of acute infection and also for the diagnosis of pre and post-natal CRS since the serological results can be inconclusive. 3,4,5,19 However, detection of rubella viral RNA in AF which may be obtained from amniocentesis at about 12 weeks of gestation allows confirmation of fetal infection. The time between maternal infection and fetal sampling is an important consideration in prenatal diagnosis.…”

“…2 Traditionally, detection of fetal viral infection relies on isolation and culture of virus or maternal and cord blood seroconversion. 3 Viral culture and subsequent identification from mother and fetuses and/or amniotic fluid has been the gold standard. This method is slow, taking between 1 to 3 weeks to obtain a positive result.…”

“…Infection prior to conception does not present a risk to the fetus, but when primary rubella infection occurs in the first 12 weeks of pregnancy, rubella virus will cross the placenta and induce generalized and persistent fetal infection in about 80% of cases. 3,8 Spontaneous abortion may take place in up to 20% of cases when rubella occurs in the first 8 weeks of pregnancy. 9,10 During the past 10 years, nationwide epidemics of rubella occurred approximately every 5 years in São Paulo, Brazil, namely in 1995, 2000 and 2007.…”