[The role of rubella specific IgM within the serological diagnosis of rubella (German measles) (authors transl)].

The sera of 327 patients were investigated for rubella specific IgA after separation of the IgM fraction by sucrose density gradient centrifugation. 1. In 96 out of 137 cases suspicious of clinical rubella, where the time for demonstration of a significant rise of the antibody titer had been missed, the demonstration of rubella specific IgM confirmed the diagnosis of German measles. This demonstration was still possible in 9 out of 10 cases 5 to 7 weeks after the onset of the disease, but in only 2 out 7 cases 8 to 15 weeks after the onset of the disease. 2. In 48 patients who had contact with patients with German measles but did not develop any symptoms, a primary infection could not be excluded by the examination of the whole serum. In 5 out of them rubella specific IgM indicted a recent rubella infection. 3. Rubella specific IgM could not be demonstrated in 47 patients who had high antibody titers but no other hints for a recent rubella infection. 4. In 89 newborns, the investigation was prompted, when elevated IgM levels were found in umbilical cord blood, or when the newborn was sick, or when a rubella infection of the mother was suspected or proven. Rubella infection of the newborn was confirmed by rubella specific IgM only if the mother had contracted German measles during the first trimester of the pregnancy (6 out of 7 cases). The diagnosis of primary rubella infection during pregnancy is proven only if 2 out the fose in antibody titer, demonstration of rubella specific IgM.