Congenital Varicella Infection

Summary

 Varicella infection during pregnancy is rare but potentially severe. Early identification, immunity assessment, and timely prophylaxis or antiviral therapy are essential to minimize maternal and fetal complications, including congenital varicella syndrome and neonatal varicella.

Epidemiology

 Varicella-zoster virus (VZV) infection is uncommon in pregnancy due to widespread immunity; seroprevalence is approximately 95% in the general population. Most women have immunity from previous infection or vaccination, and congenital infection occurs in fewer than 2% of cases. Despite low incidence, maternal infection carries significant morbidity and mortality for both mother and fetus.

Pathogen and Transmission

 VZV is a DNA virus responsible for:

• Chickenpox (varicella): primary infection

• Shingles (herpes zoster): viral reactivation

Transmission to the fetus occurs transplacentally from an infected mother, particularly during primary maternal infection. Maternal infection occurs via airborne droplets, direct contact with vesicular fluid, or, rarely, reactivation in immunocompromised individuals.

Clinical Features

• Maternal infection: Presents with fever, malaise, and a pruritic maculopapular rash progressing to vesicles and crusting. Complications include pneumonia, hepatitis, and encephalitis, with a maternal mortality rate of ~2%.
  
  

• Neonatal varicella:

• Mild if maternal rash occurs >5 days before delivery

• Severe if maternal rash occurs <5 days before delivery, with risk of hemorrhagic exanthem, pneumonia, encephalitis, or congenital varicella syndrome (up to 30% mortality)
  
  

• Congenital Varicella Syndrome (infection in first or second trimester):

• Skin: cicatricial scarring

• Limbs: hypoplasia

• Eyes: cataracts, chorioretinitis, microphthalmia

• CNS: microcephaly, cortical atrophy, seizures, hydrocephalus, intellectual disability

Investigations

• Maternal/newborn: Usually clinical diagnosis based on rash; confirmatory tests include PCR or direct fluorescent antibody (DFA) testing of vesicular fluid or cerebrospinal fluid. Serology can determine immunity (IgG) or acute infection (IgM).
  

• Fetus: PCR for VZV DNA in amniotic fluid or fetal blood; ultrasound to detect structural abnormalities.

Management

• Suspected exposure in pregnancy:

• Determine immunity via history or IgG testing

• Non-immune women <20 weeks: VZIG within 10 days of exposure

• Non-immune women >20 weeks: VZIG or acyclovir (days 7–14 post-exposure)
  
  

• Confirmed maternal infection:

• Acyclovir 800 mg orally five times daily for 7 days, particularly after 20 weeks gestation

• Monitor for maternal complications (pneumonia, neurological signs)

• Refer to fetal medicine for serial ultrasounds to detect abnormalities
  
  

• At delivery:

• Avoid elective delivery within 7 days of maternal rash onset

• Administer VZIG to neonates if maternal rash occurred <5 days before birth

• Treat infected neonates with acyclovir

Prevention

• Pre-pregnancy vaccination of seronegative women

• Post-exposure prophylaxis with VZIG in susceptible pregnant women within 10 days of exposure

• Breastfeeding is encouraged due to potential protective antibodies