Discrepancies in the Diagnosis of Congenital Infection Between B1 Gene Semi-Nested Polymerase Chain Reaction and Serological Analyses.

Congenital () infection, which can be caused by a primary infection during pregnancy, results in severe neurological sequelae in affected children. We have been conducting a prospective cohort study since January 2019 on pregnant women who were suspected of having primary infection based on serological tests. In this study, congenital infection was diagnosed using semi-nested polymerase chain reaction (PCR) to detect the B1 gene in the body fluids of newborns. Up until December 2023, forty-one newborns born to mothers suspected of having primary infection during pregnancy underwent B1 gene semi-nested PCR tests and anti- immunoglobulin (Ig) G and IgM measurements of their blood samples. Eight newborns showed no clinical symptoms of congenital infection; however, they were diagnosed with congenital infection according to positive PCR results. However, none of the eight infants eventually exhibited any sign of congenital infection, as their serum samples tested negative for anti- IgM and IgG until 12 months of age. Therefore, clinicians should consider discrepancies in the diagnosis of congenital infection between PCR tests using body fluids of newborns and serological tests during their infantile period.