Prevalence and importance of congenital cytomegalovirus infection in three different populations.

A Chilean population was compared to low-income and middle/upper-class populations in Birmingham, Ala., with regard to prevalence of congenital cytomegalovirus infection as well as the importance of this infection in neonatal deaths. In the highly seroimmune Chilean (98%) and low-income Birmingham (82%) groups, congenital infections occurred more often (1.7% and 1.9%, respectively) than in the less immune (56%) middle/upper-income group in Birmingham (0.6%). In 407 autopsies reviewed in Chile no neonatal deaths were attributed to cytomegalic inclusion disease, whereas in Birmingham cytomegalovirus was the cause of death in nine of 938 (1%) newborn infants. These findings further support the concept that, despite an apparent lack of protection against intrauterine transmission, maternal immunity reduces the risk of severe fetal infection.