Rubella (German measles) is caused by an RNA virus belonging to the togovirus family . The virus is spread person to person as a result of direct contact with nasal or throat droplets of infected individuals. Skin and lymph glands are the primary organs affected by the rubella virus. General characteristics of the disease include maculopapular rash, slight fever, swollen lymph nodes, joint aches, headache, and reddened eyes. In most cases the symptoms appear within 16-18 days. The rubella virus may be spread from seven days before to seven days after the appearance of the rash. The disease is usually not fatal in adults and confers lifelong immunity. The main concern about rubella is its effect in pregnant women and their unborn children. In utero infection with the rubella virus is referred to as congenital rubella syndrome (CRS) and is particularly serious during the first trimester. CRS may cause multiple physical and mental defects in the fetus. These include congenital heart disease, blindness, deafness, splenomegaly, jaundice, microencephaly, meningoencephalitis, and radiolucent bone disease. In more severe cases, CRS results in miscarriage. 10% of young women of childbearing age are susceptible to infection with the rubella virus. In 90% of cases, maternal infection with the rubella virus during the first trimester results in CRS. The presence of IgG antibodies typically point to past infection and permanent immunity of the mother. This is often referred to as the convalescent phase of the infection, and in such cases the fetus is protected. Circulating IgM antibodies to rubella in pregnant women are indicative of recent infection (an acute phase), in which case the potential for transplacental transmission of the virus to the fetus exists. If rubella-specific IgM antibodies are detected in a pregnant woman, the unborn child must be tested immediately and all the necessary precautions should be taken.
A variety of techniques are employed to diagnose clinical rubella. These include direct isolation of the virus from bodily fluids or infected tissues, hemagglutination inhibition test, immunofluorescent antibody assay, and EIAs. The immunity against rubella virus can only be verified by measuring the titers of circulating IgG antibodies against the virus. The MDI Rubella G Test and MDI Rubella M Test are sensitive EIA, which allow for accurate detection of anti-rubella IgG and IgM in human serum.