Introduction And Disease Burden

Congenital Cytomegalovirus (cCMV) affects 0.5% to 0.7% of all live births globally.
It is the leading non-genetic infectious cause of sensorineural hearing loss (SNHL) and neurodevelopmental disabilities, including cerebral palsy and cognitive impairments.
Only 10% to 15% of infected neonates present as symptomatic at birth with microcephaly, petechiae, hepatosplenomegaly, and intrauterine growth restriction.
Crucially, up to 15% to 20% of asymptomatic infants develop late-onset, progressive, or fluctuating SNHL well beyond the neonatal period.

The Paradigm Shift: Targeted Vs. Universal Screening

Targeted screening (testing only those who fail newborn hearing screens or show clinical signs) misses 43% to 50% of infected neonates who eventually develop SNHL.
Diagnosis requires direct viral identification within the first 21 days of life to differentiate true congenital infection from postnatally acquired infection.
The 2026 "Minnesota Experience" proved universal screening effectively lowered the average age of the first audiology visit from 8.5 months to roughly 25 days and drastically increased case detection rates.

Modality	Clinical Utility And Protocol
Saliva PCR	Preferred screening tool with >95% sensitivity. Must be collected 1 to 2 hours after breastfeeding to avoid false positives from maternal CMV shed in breastmilk.
Urine PCR	The gold standard confirmatory test. Mandatory to confirm any positive saliva screen within the 21-day diagnostic window.
Dried Blood Spot (DBS) PCR	Leverages existing newborn metabolic screening cards. Advanced high-throughput kits now offer excellent analytical sensitivity, making nationwide universal screening logistically feasible.

Domain	Required Investigations
Laboratory	Complete blood count (to detect thrombocytopenia/neutropenia), metabolic panel, and liver function tests (specifically for elevated ALT and conjugated hyperbilirubinemia).
Neuroimaging	Cranial ultrasound is the first line to check for periventricular calcifications or subependymal cysts. Brain MRI is indicated if ultrasound is abnormal or severe neurological symptoms exist.
Audiology	Comprehensive baseline Auditory Brainstem Response (ABR) to detect immediate SNHL.
Ophthalmology	Dilated fundoscopic examination to rule out chorioretinitis, optic atrophy, or cataracts.

Symptomatic Infants: Standard care for symptomatic cCMV with central nervous system involvement is oral Valganciclovir (16 mg/kg/dose twice daily) for a prolonged 6-month duration. IV Ganciclovir is reserved for acutely ill infants or those with severe enteropathy.
Asymptomatic Infants: Treating asymptomatic infants or those with isolated SNHL remains controversial due to severe drug toxicities (dose-limiting neutropenia and hepatotoxicity).
Toxicity Monitoring: Requires weekly complete blood counts and liver function tests for the first 4 weeks, followed by monthly checks for the 6-month treatment duration.
Audiological Surveillance: Mandatory hearing tests every 3 to 6 months for the first 3 years of life, then annually until 6 years of age to catch late-onset SNHL.

Seroprevalence among Indian women of childbearing age often exceeds 90%, meaning non-primary infections (reinfection or reactivation) account for the vast majority of cCMV cases.
To overcome the economic and logistical barriers of commercial PCR kits, Indian initiatives are actively exploring multiplexing CMV PCR onto existing government-mandated dried blood spot cards used for congenital hypothyroidism screening.