OBJECTIVEHuman cytomegalovirus (HCMV) is a ubiquitous human-specific DNA virus and is the main cause of congenital virus infection worldwide. Although 90% of the congenitally infected infants are clinically asymptomatic at birth, evidences show that these infants are at risk for audiologic, neurologic, and developmental sequelae. The aim of this study was to evaluate the outcome of children with asymptomatic congenital human cytomegalovirus infection identified from a cohort of newborn infants screened for congenital HCMV infection compared with matched uninfected control subjects.

METHODSBetween July 2003 and July 2005, eligible hospitalized infants were recruited into the cohort. Serum was collected within two weeks of birth and transported to the laboratory within 24 hours, and stored at -20 degrees C. Then Real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) for the presence of HCMV DNA was used as a screening tool for the detection of congenital cytomegalovirus infection. Asymptomatic congenital HCMV infection (ACCMV) was defined as detection of HCMV during the first 2 weeks of life in the absence of any abnormal signs, symptoms, or laboratory findings. The study enrolled 41 siblings with asymptomatic congenital HCMV infection and 21 children whose neonatal screening for congenital HCMV infection showed negative results. Then they were followed up prospectively for the first years of life. A pediatric assessment, including neonatal behavioral neurological assessment (NBNA) was performed at neonatal period by a qualified pediatrician, at which time the CMV status of the infants was not yet known. At one year of age other standardised clinical evaluations were performed by the pediatrician. The Bayley scale of infant development were used to determine the intellectual and neurological development deficits, and the age-adequate neurological examinations based on the criteria by Amiel-Tison to evaluate the general movements for neurological development. Hearing screening were completed for all children to determine their hearing status. Auditory brain-stem response (ABR) and distortion product otoacoustic emission (DPOAE) have been used to accurately diagnose moderate to profound congenital sensorineural hearing loss.

RESULTThere was no significant difference between the mean NBNA score of HCMV group (38.8 +/- 2.75) and the control group (38.5 +/- 2.29) (t = 0.98, P > 0.05). Significant difference was found between the occurrence of hearing loss in infants born with asymptomatic congenital HCMV infection compared with the control group. Audiologic abnormalities (sensorineural hearing loss, SNHL) were present in 5 of 23 congenitally infected children, however, no hearing abnormalities were detected in uninfected children (chi2 = 6.94, P < 0.01). The mean Bayley score of HCMV group (MDI 106.86 +/- 10.24 and PDI 108.45 +/- 18.25) and the control group (MDI 107.49 +/- 19.31 and PDI 107.19 +/- 10.98) did not differ significantly (t = 0.33, P > 0.05, t = 0.35, P > 0.05). Otherwise, there was no significant difference in 52 Amiel-Tison neurological scale between the two groups.

CONCLUSIONThese data suggest that asymptomatic congenital cytomegalovirus infection may be associated with a broad range of audiologic differences in early infancy. Continued monitoring of their hearing status in the first years of life is necessary in these children because further progression of hearing loss is possible. However, asymptomatic congenital HCMV infection is not associated with abnormalities in growth, or neurodevelopmental deficits.