Chronological changes of incidence and prognosis of children with asymptomatic congenital cytomegalovirus infection in Sapporo, Japan

Congenital CMV infection, as demonstrated by isolation of the virus within the first week of life, was diagnosed in infants born in Sapporo, Japan, during the 26-year period between 1977 and 2002.Congenital infection was diagnosed in 37 (0.31%) of 11,938 infants. Thirty-two infants were (86.5%) asymptomatic and 5 (13.5%) were symptomatic at birth.Although a decrease in the total incidence of congenital CMV infection has been seen in recent years, screening of congenital infection at birth seems to be necessary to detect late-onset neurodevelopmental sequelae.Human cytomegalovirus (CMV) is the most common cause of congenital and perinatal infections throughout the world. The prevalence of congenital CMV infection varies widely between different populations (0.2–3.0%). [1] Less than 5% of the infants with congenital CMV infection have typical symptoms of cytomegalic inclusion disease (CID), another 5% have atypical symptoms of CID, and the remainder (90%) are asymptomatic at the time of delivery. Factors that have been associated with a poor neurodevelopmental prognosis include the presence of microcephaly, chorioretinitis, intracranial calcification, hydrocephalus or neurologic abnormalities at birth. [2-4]A decrease in the prevalence of serum antibodies against CMV has been documented in recent years in consequence to improvement in the social and economic conditions in Japan especially in the last 20 years. [5-7] We have studied the incidence of congenital CMV infection in Japan as reported previously. [8,9]Although asymptomatic at birth, 5 to 17% of infants with these asymptomatic congenital CMV infections will develop progressive sensorineural hearing loss (SNHL) or other neurodevelopmental difficulties within first 4 years of life. [10,11] Follow-up studies in children with asymptomatic congenital CMV infection have shown that SNHL is the most common consequence of this infection. However, prediction of which infants will have developmental disabilities remains