Rubella Virus

The primary medical danger of rubella is the infection of pregnant women because it can cause congenital rubella syndrome (CRS) in a developing fetus. Since the introduction of the measles-mumps-rubella (MMR) vaccine, rubella is much less common, however, several countries still do not include this vaccine in their immunization schedule. In the absence of vaccination, rubella is an endemic disease with epidemics every 6 to 9 years. Rubella is spread by coughing and sneezing and the virus resides in the nose and throat of an infected person with an average incubation period of 14-21 days. A person infected with rubella may spread the disease to others beginning one week before the rash occurs. Symptoms generally occur 2-3 weeks after exposure to the virus and includes a mild fever, headache and runny nose.

CONGENITAL INFECTION

A rubella infection just before conception (0-28 days) or during the first trimester in pregnancy has the highest rate of transmission to the fetus (90%) resulting in congenital rubella syndrome (CRS). At 14 weeks, this incidence is reduced to 52%, and by the end of the second trimester, the incidence drops to 25%. Fetal rubella infection often results in spontaneous abortion or severe fetal defects, including heart, brain, ear or eye malformations, deafness, microcephaly and mental retardation. Before the introduction of the vaccine, up to 4 babies in every 1000 live births were born with CRS.