Published online by Cambridge University Press: 01 August 2007
Cytomegalovirus (CMV) is the most frequent cause of congenital viral infection,1 with a prevalence of 0.5 to 1% of all live births, and the leading infectious cause of sensorineural deafness and mental retardation.1 As other Herpesviridae, CMV fetal infection can develop following both primary and recurrent maternal infection. Vertical transmission rate is around 30% following primary infection and 2 to 3% following recurrent infection.2 Effects on the unborn as well as on the newborn are widely variable. It is estimated that only 5 to 10% of infected newborns have symptoms at birth, whereas around 90% of congenitally infected infants are asymptomatic although 5–15% of these infants will develop some degree of sensorineural hearing loss.3