Specific and non-specific serological markers in the screening for congenital CMV infection.

IgM antibodies specific for cytomegalovirus (CMV) were demonstrated in 15 (2.6%) of 575 umbilical cord sera obtained from newborns in Kuwait. Some 93% and 50% of these CMV-IgM positive cord sera displayed markedly raised (more than normal mean +2 S.D.) content of total IgM and IgA respectively. In contrast, only 0.2 and 1.8% of the CMV-IgM negative cord sera had elevated total IgM and IgA, respectively. Rheumatoid factor (RF) was demonstrable, at concentrations of 30 IU/ml or more, in 67% of the CMV-IgM positive as compared with 3.2% of the CMV-IgM negative sera whereas interferon alpha was found in the serum of only one of these infants. These results indicate that raised total immunoglobulin, in particular IgM, concentrations and the detection of RF in cord blood are useful non-specific markers for the identification of congenital CMV infection.