Congenital Cytomegalovirus Infection in Mothers with Preconceptional Immunity –a Serologic Pitfall

– Background: Cytomegalovirus (CMV) is a leading cause of congenital infections worldwide. Transmission of CMV can occur due to a maternal primary infection in previously seronegative women or after a non-primary infection (reactivation or reinfection) in women with preconceptional immunity. Recent studies have shown that the majority of newborns with CMV infection are born to mothers with non-primary CMV infection.

– Case Report: We report a case of a 34-week male infant, with low birth weight, who presented with hepatosplenomegaly, petechiae and jaundice at day one of life. Maternal CMV serology prior to conception indicated CMV infection in the past (positive CMV-immunoglobulin G (IgG) with a negative CMV-immunoglobulin M (IgM)). Antenatal ultrasounds revealed intrauterine growth restriction and an echogenic bowel. Newborn laboratory studies showed decreased platelet count (105,000/μL) and hyperbilirubinemia (total bilirubin level at 9,74 mg/l). Cranial ultrasound revealed ventricular enlargement and magnetic resonance imaging of the brain performed at day 20 of life showed no calcifications or other abnormalities. Ophthalmological evaluation was normal but the child failed neonatal hearing screening. CMV polymerase chain reaction (PCR) testing in urine was positive, confirming the infection. The viral load in peripheral blood was superior than 5,000 copies/mL. Maternal peripartum serology was the same as prior to conception: IgM remained negative and there was no elevation of IgG titers. The child started antiviral treatment with valganciclovir, had a normal hearing test at 3 months and is currently with 5 months, showing a normal neurodevelopment.

– Conclusion: This case highlights the pitfalls of CMV serology interpretation in non-primary infection during pregnancy. CMV congenital infection must be considered in a fetus or newborns with suggestive signs, even if the mother has preconceptional immunity and there is no increase in maternal CMV-IgG or CMV-IgM remains negative.