Varicella Zoster Virus

Question 1

Definition

Answer 1

Aetiology – transmission is respiratory, 70% attach rate in susceptible individuals

Incubation 10-21 days; infectious 48 hours before rash until the vesicles crust over (~5 days)

Transfer to baby can be transplacental, ascending vaginal or contact after delivery with lesions

90% of UK women immune

“loss of red reflex” = Rubella, VZV

Question 2

Signs and symptoms

Answer 2

Maternal chickenpox – risk of encephalitis, pneumonia and sepsis

• Prodromal fever, malaise, myalgia
• Generalised rash (macular  popular  vesicular; different lesions at different stages)

 

Congenital varicella syndrome (VZV antepartum – maternal transmission 13-20w GA  2% risk):

• Eyes (chorioretinitis  cataracts)
• CNS (microcephaly)
• MSK (limb hypoplasia, cutaneous scarring)
• IUGR

 

Neonatal varicella infection (VZV intra-/post-partum – maternal infection 7 days before or after birth):

• Mild disease
• Disseminated skin lesions ( purpura fulminans)
• Pneumonia
• Visceral infections (i.e. hepatitis)

Question 3

Investigations

Answer 3

Booking  check previous maternal exposure:

• If NOT  avoid contact during pregnancy (if contact, seek medical advice)  significant contact is defined as being in the same room as someone for 15 mins or more, or face-to-face contact

Primary infection is typically a CLINICAL diagnosis

• If diagnosis in doubt, can do TWO tests:
  
  • Immunofluorescence of basal epithelial cells scraped from vesicle
  • VZV DNA PCR of lesion (swabbed)

To determine immunity, can test for IgM and IgG antibodies to varicella zoster

If unsure of immune status, check for VZV IgG before giving therapy

Question 4

Management

Answer 4

N.B. shingles during pregnancy does not pose a risk

Antenatal chickenpox:

• VZIG (within 10 days of exposure) before20/40 gestation
• Considered infectious for 21 days after exposure if they don’t receive VZIG
• Considered infectious for 28 days after exposure if they do receive VZIG
• Once chickenpox symptoms have developed, VZIG cannot be given
• PO Aciclovir (800mg 5/day for 7 days) if woman presents within 24 hours of rash onset and is > 20 weeks Or day 7- 14 after exposure
• Consider aciclovir in < 20 weeks
• IV aciclovir given to ALL women with severe disease
• Hospital admission (if risk factors are present: smoking, chronic lung disease, corticosteroids or of being in the latter half of pregnancy)  nursed in isolation from babies and pregnant women
• Consider referral to foetal medicine specialist – at 16-20 weeks or 5 weeks after infection

 

Intrapartum chickenpox – biggest risk of neonatal varicellaif maternal infection occurs ±7 days of birth:

• Delay delivery until 7 days after onset of the rash (allow time for passive transfer of antibodies)
• Neonatal VZIG if…
• Birth occurs <7 days onset of maternal rash
• Mother develops chickenpox <7 days of delivery NO vaccination

 

Postpartum chickenpox:

• Neonatal ophthalmic examination should be organised after birth
• The infant should be monitored for signs of infection until 28 days after the onset of maternal infection
• Neonatal infection should be treated with aciclovir
• SAFE TO BREASTFEED

Question 5

Complications

Answer 5

Summary:

If doubt about mother previously having chickenpox, maternal blood urgently checked for varicella antibodies

If non-immune: VZIG should be given ASAP (this is effective up to 10 days post-exposure)

Oral aciclovir given if pregnant women with chickenpox present within 24 hours of rash onset and >20 weeks

 

Complications – delivery during the viraemic period may be EXTREMELY HAZARDOUS:

Risks:

• Bleeding
• Thrombocytopaenia
• DIC
• Hepatitis
• Varicella infection of the new-born

Characterised by:

• Skin scarring in a dermatomal distribution
• Eye defects: microphthalmia, chorioretinitis, cataracts, optic atrophy
• Hypoplasia of the limbs

Low risk of a non-immune pregnant woman getting chickenpox from someone with shingles