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Varicella zoster

Extracted from Survival Guide to Midwifery, 2nd Edition (2012) Diane M. Fraser and Margaret A. Cooper, Oxford; Churchill Livingstone: 2012. Courtesy Elsevier

Varicella zoster virus (VZV) is a highly contagious DNA virus of the herpes family, transmitted by respiratory droplets and contact with vesicle fluid. It causes varicella (chickenpox). The virus has an incubation period of 10-20 days and is infectious for 48 hours before the rash appears until the vesicles crust over. Maternal deaths have been associated with varicella infection during pregnancy. Effects on the fetus vary with the length of gestation at the time of the infection:

Maternal infection during the first 20 weeks of pregnancy

  • 2% risk of fetal varicella syndrome (FVS)
  • Symptoms can include skin lesions and scarring in a dermatomal distribution, eye problems such as chorioretinitis and cataracts, and skeletal anomalies, in particular limb hypoplasia
  • Severe neurological problems may include encephalitis, microcephaly and significant developmental delay
  • About 30% of babies born with skin lesions die in the first months of life

Maternal chickenpox from 20 weeks' gestation up to almost the time of birth (at least)

  • A milder form of neonatal varicella that does not result in negative sequelae for the neonate

Maternal infection after 36 weeks and particularly in the week before the birth to 2 days after

  • Infection rates of up to 50%
  • About 25% of those infected will develop neonatal clinical varicella (or varicella infection of the newborn)
  • Newborns are also at risk of contracting varicella from mothers or siblings in the postnatal period
  • Most affected babies will develop a vesicular rash and about 30% will die
  • Other complications of neonatal varicella include clinical sepsis, pneumonia, pyoderma and hepatitis
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