New advances in the diagnosis of congenital cytomegalovirus infection

Abstract

With the advances in anticytomegalovirus (anti-CMV) serology, the new recombinant IgM tests seem likely to become the screening tests for pregnant women whose prepregnancy serological status for CMV is unknown. When a woman is found to be IgM-positive, further diagnostic evaluation focused on determining whether this is due to a primary infection should be carried out. Maternal primary infections that were difficult to determine until a few years ago unless documented by seroconversion can now be readily diagnosed from the presence of low-avidity anti-CMV antibody which persists for approximately 20 weeks after primary infection. In primarily infected mothers prenatal diagnosis can be performed between 21 and 23 weeks of gestation, and the amniotic fluid (AF) represents the pathological material of choice to determine intrauterine virus transmission. In AF, the virus can be detected by culture and/or PCR. Both procedures differentiate uninfected from infected fetuses, but cannot predict fetal outcome. The determination of the viral load in AF carried out by quantitative PCR is more promising and could represent an important starting point for preemptive fetal therapy.