Congenital varicella syndrome (CVS) is a rare condition affecting a fetus or newborn when the mother contracts the varicella-zoster virus (VZV), which causes chickenpox, early in pregnancy. Affected babies exhibit distinct abnormalities at birth.
The Cause and Critical Timing of Infection
Congenital varicella syndrome occurs when the varicella-zoster virus, contracted by the mother, travels through the placenta to the developing fetus. The timing of the maternal chickenpox infection during pregnancy significantly influences the risk and severity of the syndrome.
The period of highest risk for the fetus developing congenital varicella syndrome is during the first 20 weeks of pregnancy. If a mother contracts chickenpox within the first 12 weeks, the risk of the baby developing CVS is approximately 0.4%. This risk increases to about 2% if the infection occurs between weeks 13 and 20 of gestation.
After 20 weeks of pregnancy, the risk of congenital varicella syndrome becomes very low. It is important to distinguish CVS from neonatal varicella, a separate condition occurring when the mother develops chickenpox very close to delivery, typically within five days before or two days after birth. Neonatal varicella can be severe for the newborn due to the absence of protective maternal antibodies.
Identifying the Syndrome
Babies born with congenital varicella syndrome present with characteristic features affecting multiple body systems. These manifestations stem from the virus damaging developing fetal tissues, particularly during periods of organ formation.
Skin abnormalities are a common sign, appearing as distinctive zig-zag or dermatomal scarring (cicatricial lesions). These scars can be thickened or overgrown, frequently observed on the arms and legs. Such scarring reflects damage to nerve pathways during development.
Limb abnormalities are also frequently seen, including limb hypoplasia, which means underdeveloped arms or legs. This can manifest as deficiencies, malformations, or reduced growth in the limbs. The underdevelopment may also affect digits, leading to smaller or absent fingers and toes.
Eye issues are another common feature, with potential problems such as chorioretinitis, an inflammation affecting the retina and choroid layers of the eye. Other ocular defects include microphthalmia, characterized by abnormally small eyes, and cataracts, which involve clouding of the eye’s lens. These eye abnormalities can impact vision significantly.
Neurological complications are also associated with the syndrome, stemming from brain abnormalities. These can include cortical atrophy (degeneration of the outer portion of the brain) and microcephaly (abnormally small head circumference). Seizures and developmental delays, including intellectual disabilities, can also be present.
Diagnosis of congenital varicella syndrome can sometimes be suggested before birth through detailed prenatal ultrasound examinations, which may reveal findings such as limb deformities or brain problems. After birth, the diagnosis is confirmed by a physical examination of the newborn, alongside a documented history of maternal varicella infection during the early stages of pregnancy.
Prevention and Management Strategies
Preventing congenital varicella syndrome primarily involves ensuring a pregnant individual is immune to the varicella-zoster virus before conception. The most effective way to achieve this is through vaccination with the varicella vaccine. This vaccine is a live virus vaccine and should be administered before pregnancy, with a recommendation to wait at least one month after the second dose before attempting to conceive.
Confirming immunity before pregnancy is also an important preventative step. If a person planning pregnancy is unsure of their immunity status, a blood test can determine if they have antibodies to the virus. Individuals found to be non-immune should receive the vaccine to reduce the risk of infection during a future pregnancy.
If a non-immune pregnant person is exposed to chickenpox, varicella-zoster immune globulin (VZIG) may be administered. The primary purpose of VZIG is to reduce the severity of the mother’s illness and potential complications like pneumonia. While VZIG may not entirely eliminate the risk of fetal infection, it offers the only chance to mitigate the severe consequences of congenital varicella syndrome if exposure occurs before 20 weeks of gestation.
For an infant born with congenital varicella syndrome, there is no cure for the existing birth defects caused by the intrauterine viral damage. Therefore, care is supportive and focuses on managing the specific symptoms and complications each child experiences. This often involves a multidisciplinary team of specialists tailored to the child’s needs.
This team may include physical therapists to address limb abnormalities, ophthalmologists for eye conditions, and neurologists for brain-related issues and seizures. Supportive care aims to improve the child’s quality of life and address developmental challenges through ongoing therapies and interventions.