ABSTRACT
Important distinctions have been drawn between congenital infection, which follows a primary maternal infection and that which results from an infection in a previously infected mother (12,14-20). Transmission to the fetus occurs in about 30% to 50% of pregnancies complicated by a primary HCMV infection during pregnancy compared to about 1% following recurrent infection. Initial reports suggested that severe sequelae were almost exclusively seen following pregnancies complicated by primary HCMV infection (9,15). For example, Fowler et al. (12) found that sequelae occurred in 25% of 125 infants with congenital infection following primary CMV infection during pregnancy but in only 8% of 64 infants with congenital infection born to mothers who were HCMV seropositive prior to pregnancy. More importantly, none of the infected infants born to seropositive mothers developed severe sequelae; defined as bilateral hearing loss or mental retardation (an IQ < 70). These sequelae occurred only among infants born to mothers who had a primary infection during pregnancy. Such observations suggest that maternal immunity to HCMV prior to pregnancy prevents the majority of severe sequelae
associated with congenital infection and form an important argument for the feasibility of developing HCMV vaccines to prevent congenital HCMV disease.
