PEDBASE.org - The Pediatric Database - Detailed information of CONGENITAL VARICELLA

CONGENITAL VARICELLA

DEFINITION:

A contagious infectious disease caused by a DNA herpesvirus Varicella causing varicella embryopathy (VE) or varicella of the newborn (VON).

EPIDEMIOLOGY:

incidence: ?
age of onset:
- newborn
risk factors:
- exposure to variclla

PATHOGENESIS:

1. Routes of Transmission

1. Neonatal

1. Antenatal (in utero)

1. Primary Maternal Infection

present with VE (in utero infection)
incidence of varicella during pregnancy is 1-5/10,000 pregnancies
25% vertical transplacental transmission rate
congenital malformations (VE) are noted in 2.2% of fetuses infected in the first 20 weeks of pregnancy (NEJM March 31, 1994)

2. Perinatal

present with VON (perinatal infection)
if maternal varicella occurs 5-21 days prior to delivery, neonatal disease appears in the first 4 days with a good prognosis (due to protective maternal IgG)
if maternal varicella occurs 5 days prior delivery to 2 days after delivery, neonatal disease presents be-tween 5-10 days of age and is mild to severe with up to a 30% mortality rate

3. Postnatal

infected postnatally by respiratory route
term infants at no higher risk than older children except in some seronegative infants less than 1 month of age
preterm infants are at increased risk due to a lack of placental varicella IgG transfer which usually occurs late in the 3rd trimester

2. Childhood

1. Horizontal Transmission

direct human-to-human contact
- by direct contact with lesions
- by airborne droplets

2. Background

humans are the only source of infection
incubation period: 14-21 days (childhood), 9-15 days (neonatal)
secondary attack rate is 90%
immunity is lifelong
varicella rather than zoster is associated with transmission to the fetus or neonate
asymptomatic primary infection is rare but reinfection is not contagious until the last lesion has crusted

CLINICAL FEATURES:

1. Varicella Embryopathy (Congenital or Fetal Varicella Syndrome)

1. Central Nervous System Manifestations

microcephaly
paralysis
psychomotor retardation
seizures

2. Ocular Manifestations

cataracts
chorioretinitis
Horner's Syndrome
microphthalmia
nystagmus

3. Musculoskeletal Manifestations

cicatrical dermatomal skin lesions and scarring
unilateral atrophy of a limb with scarring and paresis
rudimentary digits
high incidence of zoster in the first 10 years of life (also if perinatal- or postnatally-acquired)

Note: Fetuses infected within the last 3 weeks of pregnancy may be mildly affected (few vesicular lesions) or severely affected with fever, hemorrhagic rash, pneumonia, and generalized necrotic lesions of the viscera

2. Varicella of the Newborn (VON)

1. Prodrome

poor feeding, slight fever, malaise
scarlatiniform or morbilliform rash

2. Systemic

mild fever, malaise, poor feeding
generalized pruritic, vesicular rash

3. Complications

meningoencephalitis
pneumonia, respiratory distress
pericarditis, endocarditits, myocarditis
hepatitis, pancreatitis
glomerulonephritis
Other - arthritis, acute myositis, bacterial superin-fection, purpura fulminans, Reye Syndrome, thrombocytopenia

INVESTIGATIONS:

1. Diagnostic

1. Virology

isolate virus from vesicular fluid

2. Serology

varicella-specific IgM in fetal blood samples

3. Others

to detect varicella antigen or nucleic acid
- Tzanck preparation - look for inclusion bodies
- ELISA
- counterimmunoelecrophoresis
- immunofluorescence

2. Imaging Studies

1. CT (Head)

cortical and cerebellar atrophy
encephaloclastic lesions

MANAGEMENT:

1. Medical

1. Acyclovir

15 mg/kg IV tid for 7 days
indicated for moderate to severe cases
side effects:
- neurotoxicity - lethargy, seizures, coma, agitation, jitteriness

2. Varicella-zoster Immune Globulin (VZIG)

125 units IM
indicated in infants:
- born to mothers who developed varicella within 5 days before delivery or 2 days after delivery
- at risk premature infants less than 28 weeks or less than 1000 grams in weight
- exposed seronegative mothers (thought to prevent fetal or neonatal infection or teratogenesis)

Pediatric Database - CONGENITAL VARICELLA

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