Introduction to Congenital Varicella Zoster Infections

Congenital Varicella Zoster Virus (VZV) infection, also known as congenital varicella syndrome (CVS), occurs when a pregnant woman contracts primary VZV infection (chickenpox) and transmits the virus to her fetus. This rare but serious condition can lead to significant morbidity and mortality in affected infants.

• VZV is a DNA virus of the Herpesviridae family
• Incidence of CVS: Approximately 1-2% when maternal infection occurs in the first 20 weeks of gestation
• Risk is highest when maternal infection occurs between 13-20 weeks gestation

Understanding the pathophysiology, clinical presentation, and management of congenital varicella is crucial for healthcare providers to optimize outcomes for affected infants and provide appropriate counseling to pregnant women.

Transmission of Congenital Varicella Zoster

The risk and consequences of vertical transmission of VZV depend on the timing of maternal infection during pregnancy:

Timing of Maternal Infection

• First trimester (0-12 weeks):
  • Low risk of transmission
  • Potential for severe embryopathy
• Second trimester (13-28 weeks):
  • Highest risk of congenital varicella syndrome
  • Peak risk between 13-20 weeks
• Third trimester (>28 weeks):
  • Lower risk of congenital syndrome
  • Increased risk of neonatal varicella if infection occurs near term

Mechanisms of Transmission

• Transplacental: Primary route for congenital infection
• Ascending infection: Rare, but possible
• Perinatal: Can occur if maternal infection is near delivery date

Risk Factors

• Maternal primary VZV infection during pregnancy
• Lack of maternal immunity to VZV
• Immunocompromised pregnant women

Clinical Manifestations of Congenital Varicella Zoster

The clinical presentation of congenital varicella can vary widely, ranging from asymptomatic infection to severe multisystem involvement:

Congenital Varicella Syndrome (CVS)

Classical features include:

• Cutaneous manifestations:
  • Cicatricial skin lesions in a dermatomal distribution
  • Hypopigmented or hyperpigmented scars
• Neurological abnormalities:
  • Microcephaly
  • Cortical atrophy
  • Seizures
  • Intellectual disability
• Ocular defects:
  • Chorioretinitis
  • Microphthalmia
  • Cataracts
  • Optic atrophy
• Limb abnormalities:
  • Hypoplasia of limbs
  • Muscular atrophy
  • Joint contractures
• Other manifestations:
  • Intrauterine growth restriction
  • Gastrointestinal abnormalities
  • Cardiovascular defects

Neonatal Varicella

Occurs when maternal infection is near term:

• Mild disease: If maternal infection is >5 days before delivery
• Severe disease: If maternal infection is within 5 days before to 2 days after delivery
• Clinical features:
  • Vesicular rash
  • Pneumonia
  • Hepatitis
  • Encephalitis

Long-term Complications

• Developmental delays
• Learning disabilities
• Visual impairment
• Motor deficits
• Recurrent zoster infections

Diagnosis of Congenital Varicella Zoster

Diagnosing congenital varicella requires a combination of clinical assessment, maternal history, and laboratory investigations:

Maternal Diagnosis

• Clinical presentation of chickenpox during pregnancy
• Serological testing:
  • VZV-specific IgM antibodies
  • Significant rise in VZV IgG antibodies
• PCR detection of VZV DNA in vesicular fluid or blood

Prenatal Diagnosis

• Ultrasonography: May reveal fetal abnormalities consistent with CVS
• Amniocentesis: PCR detection of VZV DNA in amniotic fluid
• Fetal blood sampling: Rarely performed, can detect VZV DNA or antibodies

Neonatal Diagnosis

• Clinical examination for characteristic features of CVS
• Laboratory investigations:
  • PCR detection of VZV DNA in blood, CSF, or skin lesions
  • Serological testing for VZV-specific IgM antibodies
• Imaging studies:
  • Brain MRI or CT to assess neurological involvement
  • Ophthalmological examination
  • Skeletal radiographs

Differential Diagnosis

Consider other congenital infections and syndromes, including:

• Other TORCH infections (Toxoplasmosis, Rubella, CMV, Herpes simplex)
• Congenital Zika syndrome
• Fetal alcohol syndrome
• Genetic disorders affecting limb development

Management of Congenital Varicella Zoster

Management of congenital varicella involves prevention, treatment of maternal infection, and care of affected infants:

Prevention

• Vaccination: Recommended for non-immune women before pregnancy
• Avoid exposure: Pregnant women should avoid contact with individuals with active varicella
• Post-exposure prophylaxis:
  • Varicella-Zoster Immunoglobulin (VZIG) within 96 hours of exposure for susceptible pregnant women
  • Acyclovir may be considered if VZIG is unavailable

Management of Maternal Infection

• Antiviral therapy: Acyclovir or valacyclovir for pregnant women with varicella
• Supportive care: Symptomatic treatment, hydration
• Fetal monitoring: Regular ultrasound examinations

Management of Affected Infants

• Neonatal varicella:
  • VZIG administration immediately after birth
  • Intravenous acyclovir for 7-10 days
• Congenital Varicella Syndrome:
  • Multidisciplinary approach involving neonatologists, neurologists, ophthalmologists, and other specialists
  • Symptomatic treatment of specific manifestations
  • Early intervention programs for developmental support
• Long-term follow-up:
  • Regular developmental assessments
  • Ophthalmological examinations
  • Neurological evaluations
  • Physical and occupational therapy as needed

Counseling and Support

• Genetic counseling for future pregnancies
• Psychosocial support for families
• Education about potential long-term complications and care needs

Future Directions

• Development of more effective prenatal diagnostic techniques
• Research on potential in utero treatments
• Long-term outcome studies of infants with congenital varicella

Congenital varicella zoster infections can have significant implications for fetal and neonatal health, emphasizing the importance of prevention, early diagnosis, and appropriate management strategies. Healthcare providers play a crucial role in educating, screening, and providing comprehensive care to minimize the impact of these infections on maternal and child health.