Comparison of various serological methods and diagnostic kits for the detection of acute, recent, and previous rubella infection, vaccination, and congenital infections.

The antibody development after natural rubella infection and rubella vaccination has been followed in 802 sera from 493 patients and 71 sera from 22 vaccinees. Also examined were 67 sera from 28 infants with rubella embryopathy and sera from 50 children with presumed prenatal infection. In addition, 777 sera from 641 patients tested for routine rubella diagnosis were studied. Anamnestic information was available from all these patients. These sera were assayed for IgM antibody detection by sucrose density gradient (SDG), the commercial ELISAs (Enzygnost IgM and Rubazyme M), and the non-commercial anti-my-hemadsorption immunosorbent technique (HIT). For the determination of IgG antibodies the hemagglutination inhibition test (HAI), the commercial ELISAs (Enzygnost IgG, Rubazyme), and a single radial hemolysis test (SRH) were used. The SDG and HIT were less sensitive for IgM antibody detection than the two ELISAs, particularly when IgM concentrations were low. In total 26.5% of the IgM results with the newer tests were discordant with SDG, but only 0.5-1.3% of these results were not explicable when the clinical data was considered. Problems were encountered with all IgM assay systems used. For the detection of rubella antibodies after acute infection and vaccination the ELISA Enzygnost IgG was as sensitive as the HAI whereas the ELISA Rubazyme and SRH detected antibodies with some delay. Corresponding results with all tests were found more than 25 days after acute infection and more than 50 days after vaccination. All methods can be used for detection of antibodies in infants with rubella embryopathy. The results of this study suggest that certain combinations of tests can be used for the reliable detection of rubella infection.