Prevalence of human cytomegalovirus congenital infection in Portuguese newborns.

Human cytomegalovirus (HCMV) is considered the most frequent cause of congenital infection, occurring in 0.2 to 2.2% of all live births. Since this is a wide range of prevalences observed in different studies, it would be desirable to investigate the prevalence of this infection at national level. The aim of this study was the evaluation of the national prevalence of HCMV congenital infection. We analysed a total of 3,600 Guthrie cards collected from Portuguese newborns during a period of 14 months (August 2003 to September 2004). The cards covered all regions of Portugal and were proportional to the number of births in each region. A heat DNA extraction method was used, followed by DNA amplification by nested PCR. Sensitivity and specificity of this method were evaluated as 93% and 100%, respectively, using 28 cards from HCMV-positive and 280 cards from HCMV-negative children. The national prevalence of congenital HCMV was determined as 1.05% (95% confidence interval: 0.748-1.446). This is the first study of the prevalence of HCMV congenital infection at national level in Portugal. It suggests that Portugal may have one of the highest prevalences of congenital HCMV infection in Europe.