Congenital Cytomegalovirus (CMV) Infection : How To Reduce the Cost of a Screening Program

BACKGROUND: CMV is the leading cause of congenital infection in humans. Congenitally infected infants, both symptomatic and asymptomatic at birth, may develop sequelae, particularly hearing loss and brain damage. Therefore, universal newborn screening for CMV should be recommended to detect sequelae as early as possible. OBJECTIVE: To identify a reliable and cheap method to screen newborns at birth and to select a sample easy to collect and store. DESIGN/METHODS: Phase 1: We collected liquid urine and liquid and dried saliva samples (DSS) from all infants born at our hospital during the study period, within the first 3 wks of life, whose parents gave informed consent. Liquid specimens were tested for CMV by “shell-vial” culture (SVC) and by nested PCR. Dried specimens, collected on COPAN nylon-flocked swabs, were tested by nested PCR. For nested PCR, CMV DNA was extracted using the QIamp DNA Mini kit (QIAGEN). Phase 2: If DSS test was suitable for CMV DNA detection, we compared the above mentioned method with a commercial Real-time PCR, using an inexpensive pre-PCR treatment (vortexing followed by thermal shock: 45” at 70°C, fast cooling and storage at -80°C). RESULTS: Phase 1: We enrolled 365 neonates (mean GA 36.8 wks, mean BW 2698 g). CMV was detected in liquid urine by SVC in 9/365 (2.5%) neonates, and those were diagnosed as congenitally infected. In all infants with congenital infection, viral DNA was detected in saliva samples, both liquid and dried, by nested PCR. Phase 2: DSS were collected from 64 children with congenital CMV infection and tested for CMV using both nested PCR and Real-time PCR. Sensitivity, specificity and concordance rate of Real-time PCR with nested PCR were 96%, 100% and 97% respectively. CONCLUSIONS: Ease of collection, handling and storage of DSS, in addition to an inexpensive pre-PCR treatment, could make this method a reliable and innovative approach to screen newborns for CMV infection.