Epstein-Barr virus and cytomegalovirus infection — formative SAQs

SAQ 1 (10 marks)

A 12-day-old term infant is reviewed on the postnatal ward for prolonged jaundice. Examination reveals petechiae over the trunk, an enlarged liver and spleen, and a head circumference on the 2nd centile. The full blood count shows a platelet count of 45 × 10⁹/L and the newborn hearing screen referred on the left. The mother reports a flu-like illness at 10 weeks' gestation but no serology was performed at the time. ^[9]

Question: Outline the diagnosis, immediate investigations, management and long-term follow-up of this infant. (10 marks) ^[10]

Model answer

Suspected diagnosis and urgency (2 marks). The combination of jaundice, petechiae, hepatosplenomegaly, thrombocytopenia, microcephaly and a failed hearing screen in a neonate is the classic presentation of symptomatic congenital cytomegalovirus infection. This is the most common congenital infection and the leading non-genetic cause of sensorineural hearing loss. The diagnosis must be confirmed now, while the infant is within the diagnostic window. ^{[10] [9]}

The critical investigation and its timing (2 marks). Send saliva or urine PCR for CMV without delay. The diagnosis of congenital CMV can only be confirmed by PCR within the first 21 days of life — after that window, a positive result cannot distinguish congenital infection from CMV acquired perinatally via breast milk or the birth canal. The Boppana saliva-PCR study established saliva as a sensitive screening sample. If the infant is already beyond 21 days, retrieve the stored newborn blood spot (Guthrie card) for retrospective CMV PCR. Supportive tests include a full blood count (thrombocytopenia, anaemia, neutropenia), liver function tests, a cranial ultrasound (periventricular calcifications), ophthalmology review (chorioretinitis) and baseline audiology. ^{[11] [9]}

Antiviral treatment (3 marks). Once congenital CMV is confirmed and the disease is symptomatic — with sensorineural hearing loss and/or central nervous system involvement such as microcephaly or intracranial calcifications — start valganciclovir 16 mg/kg/dose orally twice daily for six months. The Kimberlin trial established a hearing benefit, and the extension showed that a six-month course improves hearing and neurodevelopmental outcomes beyond a six-week course, shifting the standard of care. Monitor the neutrophil count for drug-related myelosuppression and adjust the dose or interrupt if significant neutropenia develops. ^{[8] [13]}

Long-term surveillance (3 marks). Arrange serial audiology into school age, because CMV-related sensorineural hearing loss is often late-onset or progressive and may emerge months to years after the neonatal period — a single normal newborn hearing screen does not exclude later loss. Add developmental and neurological follow-up (for cognitive and motor impairment, cerebral palsy and seizures), ophthalmology surveillance, and family counselling about the prognosis and the prevention of CMV in future pregnancies. The outcome unfolds over years, and the surveillance must match that timescale. ^{[10] [13]}