A 5-week-old infant is found to have unilateral sensorineural hearing loss on newborn follow-up. Saliva PCR for CMV DNA is positive. The pediatrician wishes to label this as congenital CMV infection and start valganciclovir. What is the correct interpretation?
- A Congenital CMV can be diagnosed only by viral detection before 3 weeks of age; after that, acquired infection cannot be excluded ✓
- B Congenital CMV is confirmed and treatment should begin immediately
- C Saliva PCR has low sensitivity, so a positive result must be ignored
- D Diagnosis requires demonstration of CMV-specific IgM, which persists lifelong
Correct answer: A. Congenital CMV can be diagnosed only by viral detection before 3 weeks of age; after that, acquired infection cannot be excluded
Explanation
The diagnostic window for congenital CMV is the first 3 weeks of life, because viruria and salivary viral shedding after that age cannot distinguish congenital infection from acquisition during delivery or through breast milk. Testing must be done on urine or saliva within that window. CMV IgM is unreliable in neonates and maternal IgG crosses the placenta. B positive PCR at 5 weeks is compatible with postnatal acquisition.
Reference: Red Book: Report of the Committee on Infectious Diseases, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.