Varicella

Question 1

Incidence
How many people have IgG
Rate in pregnancy
Who is at risk

Answer 1

90% 15 year olds in the UK have IgG - in 96 ish % pregnant woman immune
Complicates 3:1000 pregnancies
Woman from tropical and subtropical areas are more likely to be seronegative and therefore more likely to be susceptible to the disease

Question 2

What is the rate of Fetal varicella syndrome

Answer 2

<12 /40 0.55%
12-28 weeks 1.4%
>28 weeks - no reported cases

In the first 4 weeks of pregnancy very small risk FVS
FVS - doesnt occur at the time of infection but as a zoster reactivation
• FVS from 3-28 weeks in 0.9% of chicken pox pregnancies (less in T1)

Question 3

How to prevent varicella in pregnancy

Answer 3

VZV immunisation not recommended in pregnancy - live attenuated vaccine - immunity lasts 20 years
Varicella vaccination
• prepregnancy - normal or fertility tx, avoid preg for 4 weeks + avoid susceptible preg woman as can have a post vaccination rash
• postpartum is an option that should be considered for women who are found to be seronegative for varicella-zoster virus immunoglobulin G (VZV IgG) - ok to have with breastfeeding

Women who have not had chickenpox, or are known to be seronegative for chickenpox, should be advised to avoid contact with chickenpox and shingles during pregnancy and to inform healthcare workers of a potential exposure without delay

Routine screening varicella Ig is not recommended - Hx chicken pox 95% PPV for IgG

Question 4

What is varicella incubation

Answer 4

Incubation 1-3 weeks

Virus is infective 2 days before rash until they have crusted over

Question 5

How does varicella present

Answer 5

Presentation - fever, malaise and a pruritic rash that develops into crops of maculopapules, which become vesicular and crust over before healing

Zoster remains dormant in the sensory nerve root ganglion that can be reactivated in a dermatomal distribution - very unlikely to acquire from an immunocompetant zoster flare but possible

Question 6

Implications for mother with varicella

Answer 6

Complications include respiratory sx, variella pneumonia, secondary bacterial infection, haemorrhagic rash or bleeding, new pocks or fever after 6 days , neurological sx,
Increased morbidity including hepatitis pneumonia 10% and encephalitis
Mortality 0-14%

Question 7

What occurs in Fetal varicella syndrome

Including the rate of occurrence

Answer 7

Skin scarring 78% in a dermatomal distribution
Eye abnormalities 60%(microthalmia, chorioretinitis, cataracts)
Limb abnormalities 68%eg hypoplasia of the limbs
PTB/ LWL 50%
Cortical atrophy, intellectual impairment 46%
Poor sphincter control 32%
Early death 30%
Neurological abnormalities (microcephaly, cortical atrophy, Intellectual disability, bowel or bladder sphincter dysfunction)
IUGR

Question 8

How to manage a woman who was been exposure to chicken pox that has no hx of infection (13 steps)

Answer 8

• First assess the exposure - type of VZV infection (VZV vs zoster), same room for more then 15 minutes
• Not need to test people with a hx of chicken pox - can assume immunity
• Test for VZV IgG - no hx, especially if from subtropical or tropical - sometimes can request from booking bloods - 80% of woman will be + for IgG + can reassure
• If not immune, give VZIG ASAP - effective up until day 10 (max 10 days from index case rash) - prevent 50% rashes +prevent FVS
• delay VZIG until immunity status known
• Indicated anytime in pregnancy and up to 10 days postnatally
• This woman is potentially infectious Day 8-21 (or 2-28 if had VZIG)
• Check VZIG is available before promising it
• anaphylaxis to VZIG 0.1% pain and erythema at the injection site
• Do not give it to woman already receiving replacement immunoglobulin for hypogammaglobulinaemia
• Notify MW/ doc if rash forms
• Isolate from other pregnant woman
• Can repeat if repeat exposure after 3/52

Question 9

How to manage chicken pox in pregnancy

Answer 9

• immediately inform a doctor
• Symptomatic treatment and hygiene to prevent secondary infection
• No complications + Within 24 hours - 800mg 5X daily aciclovir (more then - no tx) definitely if beyond 20 weeks, maybe if earlier - not licenced need to discuss, reduces sx and shortens duration of fever
• Complications / immunocompromise - IV aciclovir 10mg/kg TDS
• VZIG has no therapeutic benefit once chickenpox has developed and should therefore not be used in pregnant women who have developed a chickenpox rash
• If woman have ‘severe’ chicken pox they should go to hospital or if she smokes, has chronic lung disease, is immunosuppressed or in the second half of her pregnancy

If over 96 hours and high risk (smoker, lung disease, immunocompromised, post 20 weeks) oral aciclovir 800mg PO 5x daily

Question 10

What are the implications of delivery with active chicken pox in pregnancy

Answer 10

• LSCS if respiratory compromise by advanced pregnancy, fetal compromise
• If delivery while the disease is active must be done with care as the risk of DIC due to thrombocytopenia or hepatitis - ideally 7 days pass between rash and delivery although sometimes needed for respiratory compromise
• For anaesthesia - balance of GA and lung compromise vs regional - epidural mayb safer as dura is not punctured but bigger needle, need a site free of lesions needed

Question 11

How does acyclovir work

Answer 11

Aciclovir is a synthetic nucleoside analogue that inhibits replication of the VZV - no data to show fetal malformations

Question 12

What is ongoing pregnancy management / pregnancy risk

Answer 12

No increase miscarriage risk if chickenpox in T1
• Detailed MFM fetal USS more than 5 weeks post infection - If abn consider MRI
• Amnio strong NPP, weak PVV in detecting fetal damage - counsel women re the choice if USS normal VZV fetal serology unhelpful but PCR may be reassuring
• Growth scans

Question 13

Neonatal management

Answer 13

Neonatal management
• High risk if maternal infection within 4 weeks of delivery - 25% clinical varicella
• Avoid delivery for at least 7 days after onset of the rash (allow for passive antibodies to cross to the fetus)
• Inform neonates
• ok to breast feed
• More then 7 days before delivery - no intervention, no isolation, BF encouraged
7 days before to 2 days after del - ZIG immediately no isolation BF encouraged
2-28 days after delivery ZIG required if pre 28 weeks or <1000g ZIFG within 96 hours but up to 10 days can be given

Infant with chickenpox - admit to paeds - mild and had IV ZIG within 24 hours of birth IV aciclovir if resp sx
No IV ZIG within 24 hours / complications IV Aciclovir