Antenatal screening for congenital infection with rubella, cytomegalovirus and toxoplasma.

The sera of 3,463 pregnant women were screened, at the first antenatal visit, for antibodies to rubella, cytomegalovirus (CMV) and Toxoplasma gondii. Rubella antibodies were detected in 97.5%, CMV antibodies in 71% and toxoplasma antibodies in 45% of women. Asymptomatic toxoplasmosis occurred during pregnancy in 3 of 609 (0.5%) and primary CMV infection in 5 of 338 (1.5%) initially seronegative women whose sera were retested at the end of their pregnancies. The observed incidence of toxoplasmosis was similar to that calculated on the basis of the age-related prevalence of antibodies found in this study. On the basis of these observations it is estimated that congenital toxoplasmosis and congenital CMV infection due to primary maternal infection each occurs in up to 2/1,000 infants in this community. Very few of these infants have obvious abnormalities at birth, but follow-up studies elsewhere have shown that many of them suffer significant long-term sequelae. Routine antenatal screening for rubella antibodies is well established and justifiable for this preventable congenital infection. However, routine antenatal screening for CMV antibodies cannot be justified at present, since neither immunization nor treatment is available. Further information is required to determine the cost-effectiveness of routine antenatal screening for toxoplasma antibodies and treatment of proven maternal infection during pregnancy.