[28] Varicella Zoster Infection in Pregnancy Flashcards
What is varicella zoster?
A DNA virus responsible for chickenpox (as a result of primary infection) and shingles (as a result of secondary infection)
What % of the antenatal population are seropositive for varicella zoster IgG antibody?
90%
What causes a person to be seropositive for varicella zoster IgG antibody?
Previous exposure
What is the result of being seropositive for the varicella zoster IgG antibody?
These women have immunity to repeat primary infection
What is the result of 90% of women having immunity to primary varicella zoster infection?
Chickenpox is relatively uncommon in pregnancy
What is the incidence of chickenpox in pregnancy?
3 in 1000
What are the risk factors for varicella zoster infection in pregnancy?
- Unimmunised status
- Occupational exposure
- High density populations
Which occupations are at increased risk of varicella zoster infection?
- Working with children
- Hospitals
- Military recruits
How does primary varicella zoster present?
- Fever
- Malaise
- Rash
Describe the rash in primary varicella zoster
Pruritic maculopapular rash, which characteristically becomes vesicular and crusts before healing
How is a diagnosis of primary varicella zoster made?
Clinical diagnosis, made on the basis of history and examination
What investigations can be done in cases of primary varicella zoster where the diagnosis is in doubt?
- Immunoflouresence of basal epithelial cells scraped from vesicle
- PCR for varicella zoster DNA
How can immunity status be determined in varicella zoster?
Women can be tested for IgM and IgG antibodies to varicella zoster. If present, they indicate the woman has immunity
What should be done in a case where a pregnant woman has encountered a person infectious with varicella zoster?
Previous exposure should be asked about
What should be done if a woman has come into contact with someone infectious with varicella zoster, and they have had chickenpox?
Assume immunity and no further action required
What should be done if a woman has come into contact with someone infectious with varicella zoster, with no previous infection?
Varicella zoster IgG testing required to confirm immunity status
What should be done if a woman has come into contact with someone infectious with varicella zoster, and is not immune after testing?
Give varicella zoster immunoglobulin (VZIG) within 10 days of contact, or before any rash appears
What should be done if a mother presents with chickenpox?
- Give aciclovir 800mg 5tds if presenting within 24 hours of rash onset, and >20 weeks gestation
- Refer to fetal medicine specialist
Why does a woman presenting with chickenpox in pregnancy need to be referred to a fetal medicine specialist?
As she needs serial ultrasound examinations beginning at 5 weeks post-infection
Why does a woman presenting with chickenpox infection in pregnancy need serial ultrasound examinations?
To identify any fetal abnormalities
What is recommended if a woman is found to be seronegative for varicella zoster IgG?
Pre-pregnancy or post-partum vaccination
Is varicella zoster vaccination recommended in pregnancy?
No
What can happen if maternal chickenpox infection occurs within the last 4 weeks of pregnancy?
There is a significant risk of varicella infection of the newborn
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?
50%
What are the routes of transmission of varicella to cause varicella infection of the newborn?
- Transplacental
- Vaginal
- Direct contact after birth
Can varicella infection of the newborn be asymptomatic?
Yes
How is newborn varicella infection treated?
VZIG, with or without aciclovir
What is fetal varicella syndrome caused by?
Subsequent reactivation of the virus in utero as herpes zoster
When can reactivation of varicella occur to cause fetal varicella syndrome>?
Only once the fetus is infected by maternal varicella before 20 weeks gestation
What % of pregnancies infected with varicella before 20 weeks gestation will develop fetal varicella syndrome?
1-2%
What is fetal varicella syndrome characterised by?
- Skin scarring in dermatomal distribution
- Eye defects
- Hypoplasia of limbs
- Neurological abnormalities
What eye defects may be present in fetal varicella syndrome?
- Microphthalmia
- Chorioenitis
- Cataracts
- Optic atrophy
What neurological abnormalities may be present in fetal varicella syndrome?
- Microcephaly
- Cortical and spinal cord atrophy
- Seizures
- Horner’s syndrome
