Congenital Cytomegalovirus (CMV)

Summary

 Congenital CMV is the leading cause of non-hereditary sensorineural hearing loss and neurodevelopmental disabilities in children. Early recognition through prenatal imaging and laboratory testing, along with supportive care and selective antiviral therapy, is critical in improving outcomes. Preventive measures and maternal education remain key components of management.

Epidemiology

 Congenital CMV infection is the most common viral infection transmitted in utero, affecting approximately 0.5–1% of live births in the United States annually. Around one-third of maternal primary CMV infections during pregnancy result in vertical transmission, although only 5% of fetal infections lead to significant fetal damage, with the highest risk during the first trimester.

Pathogen

 CMV is a member of the herpesvirus family (herpesvirus 5). Maternal infection is often asymptomatic, though it can occasionally cause a mild flu-like illness or a mononucleosis-like syndrome with fever, splenomegaly, and hepatic involvement.

Transmission

• Maternal: via CMV-contaminated blood, urine, saliva, genital secretions, sexual contact, blood transfusions, organ transplants, or droplets.

• Fetal: transplacental transmission during maternal infection.

• Neonatal: perinatally during birth or postnatally through breast milk

Clinical Features

Maternal: Usually asymptomatic; may present with mild flu-like symptoms.

Fetal: Infection can result in miscarriage, intrauterine growth restriction (IUGR), oligohydramnios or polyhydramnios, and placental abnormalities.

Neonatal:

• Asymptomatic (∼90%): Most infants remain clinically silent, though 10% may develop late sequelae, most commonly sensorineural hearing loss.

• Symptomatic (∼10%): Manifestations include microcephaly, hydrocephalus, periventricular calcifications, chorioretinitis, sensorineural hearing loss (∼30%), hepatosplenomegaly, jaundice, thrombocytopenia, anemia, seizures, poor feeding, and “blueberry muffin” rash. Approximately 70–80% of symptomatic infants develop long-term complications such as hearing loss, vision impairment, intellectual disability, or dental abnormalities.

Diagnosis

• Prenatal: Ultrasound may detect intracranial calcifications, ventriculomegaly, hydrops fetalis, or hyperechogenic foci. Amniocentesis after 21 weeks gestation with PCR for CMV DNA confirms fetal infection. Fetal blood can be tested for CMV IgM antibodies.

• Neonatal: CMV DNA detection via PCR or viral culture from urine or saliva; CMV-specific IgM antibodies. CNS imaging may show hydrocephalus or periventricular calcifications.

• Differential diagnosis: Congenital toxoplasmosis may produce similar findings but typically presents with ring-enhancing intracranial calcifications.

Management

• Maternal: No routine treatment is required for immunocompetent women. Valacyclovir is the only antiviral approved in pregnancy.
  
  

• Fetal: Severe anemia may be treated with intrauterine transfusions; thrombocytopenia with platelet transfusions. Experimental CMV hyperimmune globulin therapy is under investigation.
  
  

• Neonatal: Symptomatic infants may receive supportive care for fluid and electrolyte imbalances, anemia, thrombocytopenia, seizures, and secondary infections. Antiviral therapy with ganciclovir, valganciclovir, or foscarnet is reserved for selected cases.

Prevention

• Frequent hand hygiene, especially after contact with children’s bodily fluids.

• Avoid sharing food or utensils with young children and refrain from kissing them on the mouth.

• Prenatal counseling on CMV risk factors is advised, particularly for seronegative women.

Prognosis

Long-term outcomes depend on the severity of infection at birth. While asymptomatic infants may develop late sequelae such as hearing loss or developmental delay, symptomatic neonates face higher morbidity and mortality, often due to disseminated intravascular coagulation, hepatic dysfunction, or secondary infections.