[28] Varicella Zoster Infection in Pregnancy

Question 1

What is varicella zoster?

Answer 1

A DNA virus responsible for chickenpox (as a result of primary infection) and shingles (as a result of secondary infection)

Question 2

What % of the antenatal population are seropositive for varicella zoster IgG antibody?

Answer 2

90%

Question 3

What causes a person to be seropositive for varicella zoster IgG antibody?

Answer 3

Previous exposure

Question 4

What is the result of being seropositive for the varicella zoster IgG antibody?

Answer 4

These women have immunity to repeat primary infection

Question 5

What is the result of 90% of women having immunity to primary varicella zoster infection?

Answer 5

Chickenpox is relatively uncommon in pregnancy

Question 6

What is the incidence of chickenpox in pregnancy?

Answer 6

3 in 1000

Question 7

What are the risk factors for varicella zoster infection in pregnancy?

Answer 7

• Unimmunised status
• Occupational exposure
• High density populations

Question 8

Which occupations are at increased risk of varicella zoster infection?

Answer 8

• Working with children
• Hospitals
• Military recruits

Question 9

How does primary varicella zoster present?

Answer 9

• Fever
• Malaise
• Rash

Question 10

Describe the rash in primary varicella zoster

Answer 10

Pruritic maculopapular rash, which characteristically becomes vesicular and crusts before healing

Question 11

How is a diagnosis of primary varicella zoster made?

Answer 11

Clinical diagnosis, made on the basis of history and examination

Question 12

What investigations can be done in cases of primary varicella zoster where the diagnosis is in doubt?

Answer 12

• Immunoflouresence of basal epithelial cells scraped from vesicle
• PCR for varicella zoster DNA

Question 13

How can immunity status be determined in varicella zoster?

Answer 13

Women can be tested for IgM and IgG antibodies to varicella zoster. If present, they indicate the woman has immunity

Question 14

What should be done in a case where a pregnant woman has encountered a person infectious with varicella zoster?

Answer 14

Previous exposure should be asked about

Question 15

What should be done if a woman has come into contact with someone infectious with varicella zoster, and they have had chickenpox?

Answer 15

Assume immunity and no further action required

Question 16

What should be done if a woman has come into contact with someone infectious with varicella zoster, with no previous infection?

Answer 16

Varicella zoster IgG testing required to confirm immunity status

Question 17

What should be done if a woman has come into contact with someone infectious with varicella zoster, and is not immune after testing?

Answer 17

Give varicella zoster immunoglobulin (VZIG) within 10 days of contact, or before any rash appears

Question 18

What should be done if a mother presents with chickenpox?

Answer 18

• Give aciclovir 800mg 5tds if presenting within 24 hours of rash onset, and >20 weeks gestation
• Refer to fetal medicine specialist

Question 19

Why does a woman presenting with chickenpox in pregnancy need to be referred to a fetal medicine specialist?

Answer 19

As she needs serial ultrasound examinations beginning at 5 weeks post-infection

Question 20

Why does a woman presenting with chickenpox infection in pregnancy need serial ultrasound examinations?

Answer 20

To identify any fetal abnormalities

Question 21

What is recommended if a woman is found to be seronegative for varicella zoster IgG?

Answer 21

Pre-pregnancy or post-partum vaccination

Question 22

Is varicella zoster vaccination recommended in pregnancy?

Answer 22

No

Question 23

What can happen if maternal chickenpox infection occurs within the last 4 weeks of pregnancy?

Answer 23

There is a significant risk of varicella infection of the newborn

Question 24

What is the risk of a baby born to a mother who had chickenpox in the last 4 weeks of pregnancy having varicella infection of the newborn?

Answer 24

50%

Question 25

What are the routes of transmission of varicella to cause varicella infection of the newborn?

Answer 25

• Transplacental
• Vaginal
• Direct contact after birth

Question 26

Can varicella infection of the newborn be asymptomatic?

Answer 26

Yes

Question 27

How is newborn varicella infection treated?

Answer 27

VZIG, with or without aciclovir

Question 28

What is fetal varicella syndrome caused by?

Answer 28

Subsequent reactivation of the virus in utero as herpes zoster

Question 29

When can reactivation of varicella occur to cause fetal varicella syndrome>?

Answer 29

Only once the fetus is infected by maternal varicella before 20 weeks gestation

Question 30

What % of pregnancies infected with varicella before 20 weeks gestation will develop fetal varicella syndrome?

Answer 30

1-2%

Question 31

What is fetal varicella syndrome characterised by?

Answer 31

• Skin scarring in dermatomal distribution
• Eye defects
• Hypoplasia of limbs
• Neurological abnormalities

Question 32

What eye defects may be present in fetal varicella syndrome?

Answer 32

• Microphthalmia
• Chorioenitis
• Cataracts
• Optic atrophy

Question 33

What neurological abnormalities may be present in fetal varicella syndrome?

Answer 33

• Microcephaly
• Cortical and spinal cord atrophy
• Seizures
• Horner’s syndrome