Detection of specific IgG and IgM antibodies in the haemagglutination inhibition test and the enzyme-linked immunoassay for the diagnosis of rubella infection.

A study has been carried out on the sera of 710 women who wished to know their state of rubella immunity using haemagglutination inhibition (HAI) and enzyme-linked immunoassay (ELISA) techniques. The majority of the women presented no symptoms. The ability of HAI to detect low antibody levels (1:8, 1:16) appears to be greater than that of Rubazyme ELISA IgG, employing the recommendations of the manufacturers. The correlation between HAI and IgG values above HAI titres of 1:16 is nearly 100%. In an additional study of 17 primary infections in pregnant women with definite rubella symptoms, the total titre of antibodies was determined by HAI and IgG and specific IgM with ELISA Rubazyme in successive samples. In four cases, IgM was clearly positive and no increase in either HAI or IgG antibodies could be demonstrated over three successive samples taken at an interval of 15 to 20 days. Therefore, we consider it necessary to determine IgM antibodies (evaluating these in the absence of the rheumatoid factor) in every doubtful case occurring in pregnant women, irrespective of whether clinical signs are present or not.