SEROLOGIC ASCERTAINMENT OF THE RISK OF VERTICAL CMV TRANSMISSION IN PREGNANCY

Background of the study: The transmission of infection from mother to fetus and the severity of damage are mainly linked to primary infection in pregnancy. Evaluation of the risk of vertical transmission in pregnancy must consider infection ascertainment, distinction between primary and reactivated infection and dating. The avoidance of invasive procedures is preferable. Obiettive: To identity serological tests useful far ascerlaining the risk of vertical transmission In pregnancy. Design: The series included 43 pregnant women (9 in the first, 18 in the second and 16 in the third trimester) with suspected CMV infection. CMV infection was diagnosed by isolation and PCR amplification on samples of urine, blood and amniotic fluid. Serological tests included CMV-IgM determination, IgG avidity test and IgM immunoblotting (in 23 cases only). Transmission of infection was assessed in the babies examining urine, saliva or blood samples or dried blood spots on Guthrie cards. Results: Eighteen women were IgM positive of whom 9 were also positive at isolation tests. The rate of vertical transmission from these women was 29% (5/17) compared to 8% (2/23) in IgM negative cases. Dating of infection on the basis of avidity test results and pregnancy stage showed that transmission occurred in 3 of 4 women with infection acquired in pregnancy, 3 of 18 with doubtful dating, and in 1 of 18 who acquired infection (primary) before pregnancy. IgM immunoblotting identified 7 reactivated infections out of 15 cases with high avidity IgG. Transinission occurred ori 2 of the 7 women with reactivated infections (both HIV+) and in 1 woman with a primary infection possibly acquired in the first months of pregnancy. Conclusion: The risk of vertical transmission of CMV infection can be ascertained in different stage.s of pregnancy by a combination of the cited serological tests.