2015 13 Chicken Pox In Pregnancy Flashcards
** Can women be immunised against varicella? **
- If seronegative, can immunise pre-pregnancy or postpartum
- Universal antenatal testing not recommended
- Safe to breastfeed with vaccine
** What measures are taken in relation to varicella at the booking visit? **
- Ask all about previous infection or vaccination
- If no hx, advise to avoid contact with disease & seek HC ASAP if exposed
** How can infection be prevented if a woman has contact with varicella? **
- Careful history
- Test for immunity if uncertain hx
- Aciclovir or valciclovir day 7-14 post-exposure if significant & non-immune
- VZIg if antivirals contraindicated or adverse effects, up to 10d after contact
** For how long is a non-immune pregnant woman exposed to chicken pox seen as infectious? **
- 8-28 days post-exposure if receive VZIg
- 8-21 days post-exposure if they don’t
** When is varicella PEP repeated? **
- Further exposure with no seroconversion
- Antivirals: 7 days from exposure
- VZIg: if exposure 3 weeks or more after last dose
** What are the risks of varicella infection as an adult? **
- Pneumonia
- Hepatitis
- Encephalitis
** What infection control measures should a pregnant woman with chicken pox take? **
- Immediately contact GP
- Avoid contact with other pregnant women & neonates until lesions crusted over
- Symptomatic treatment & hygiene to prevent secondary bacterial infection
** What is the treatment for chicken pox in pregnancy? **
- Oral Aciclovir if present within 24 hours of rash onset, esp if >24/40
- IV Aciclovir to all severe cases
- No VZIg as no benefit once developed
** When should pregnant women with chicken pox be referred to hospital? **
- Respiratory symptoms
- Other deterioration
- If at high risk of severe or complicated disease
** When & how should women with chicken pox give birth? **
- Individualised timing & mode
- For planned birth, ideally 7 days after onset to allow passive antibody transfer
- For epidural or spinal, need site away from cutaneous lesions
** What are the risks to the fetus of varicella infection in pregnancy? **
- No increased risk of 1st trimester spontaneous miscarriage
- Fetal varicella syndrome if within first 28/40
- Neonatal infection if within last 4/40 of pregnancy
** Can fetal varicella infection be diagnosed antenatally? **
- FMU referral at 16-20/40 or 5 weeks after infection
- Discussion & detailed USS
- Amniocentesis strong NPV but poor PPV, so careful consideration
** What are the neonatal considerations with varicella infection pregnancy? **
- Infection risk, esp last 4/40
- Inform neonatologist of infection at any gestation
- Breastfeeding is safe
What type of virus is VZV?
DNA virus
Human herpesvirus 3
How is VZV transmitted?
Respiratory droplets
Direct contact with vesicle fluid
Via fomites
What are the symptoms of chicken pox infection?
Fever
Malaise
Pruritic rash
Crops of maculopapules
Become vesicular then crust over
What is the incubation period of VZV?
1-3 weeks
Over what time frame is VZV infectious?
48 hours before rash appears, until vesicles crust over (usually within 5 days)
What proportion of people over 15 years old are seropositive for VZV IgG?
> 90%
What proportion of pregnancies are complicated by chicken pox?
3:1000
What is the vaccine schedule for VZV?
Live attenuated virus
2 doses 4-8 weeks apart
Immunity persists for up to 20 years
What is the cut-off for VZV IgG?
< 100
< 150 if immunocompromised
What is the dose schedule for Aciclovir in chicken pox?
800mg QDS for 5 days
What is the dose schedule for valaciclovir in chicken pox?
1000mg TDS
