Chickenpox Flashcards
VZV is transmitted by many ways, what are they?
- respiratory droplets
- direct contact with the vesicles fluid
- indirectly via fomites ( skin cells, hair, clothing, bedding)
The primary infection by VZV is characterised by … ?
Fever , malaise , pruritic rash that develops into crops of maculopapules which become vesicular and crust over before healing
How long the incubation period of VZV ?
1 -3 weeks
How long the disease is infectious in VZV ?
48 h before the rash appears
Until the vesicles crust over
( the vesicles crust over within 5 days)
What is the percentage of seropositive population for VZV?
Over 90 % of individuals > 15 years
Are sero positive for VZV
What is the percentage of pregnancies complicated by primary VZV infection ?
3 / 1000 pregnancies
[Tropical & subtropical areas are more likely to be sero negative ]
Is herpes zoster considered infectious for VZV?
Yes,
Ophthalmic zoster ( exposed) in any individual
or localized zoster in immunosuppressed patient should be considered infectious.
Can the non immune woman be immunized( against VZV) prior to pregnancy or postnatally ?
VZV vaccination prepregnancy or postnatally is an option
1- VARIVAX / VARILRIX : 2 doses / 4 - 8 weeks apart
2- avoid pregnancy 4 w after the last dose / avoid contact with pregnant women until post vaccination rash occur
3- vaccination is safe during breastfeeding
Is universal serological antenatal testing( for VZV ) recommended in UK?
No
But seronegative women could be offered vaccination postpartum
[ life attenuated vaccine]
When a pregnant woman gives a history of contact with chickenpox or shingles, how to manage?
1- confirm significant contact: ( contact in the same room for 15 min , face to face )
2- take a history to confirm previous chickenpox or shingles
3- if no previous history OR who come from tropical or subtropical countries 👉blood tests to determine VZV immunity
If a pregnant woman isn’t immune to VZV and has had a significant exposure how to manage?
VZVIG is indicated after exposure( as soon as possible & within 10 days) :
1- at any stage of pregnancy
2- postpartum if birth occurs within 10 days of exposure
Should Non immune pregnant woman who exposed to chickenpox
be considered infectious?
They should be considered infectious from:
8 - 28 days after exposure if they receive VZVIG
8 - 21 days after exposure if they don’t receive VZVIG
What are the maternal risks of varicella in pregnancy?
1-Pneumonia
2-Hepatitis
3-Encephalitis
4- Rarely death
How should the pregnant woman
Who develops chickenpox be cared for ?
1- oral ACYCLOVIR ( 800mg for 7 days) : if they present within 24 h of the onset of the rash & they are >20 weeks
2- IV acyclovir: in severe cases
♧[acyclovir ISN’T licensed in pregnancy]
3- symptomatic treatment & hygiene: to prevent secondary infection
What is the therapeutic benefit of VZVIG once the chickenpox has developed?
No therapeutic benefit
👉 not to be used
When the pregnant woman with chickenpox should be referred to hospital?
🚩 symptoms & signs of severe case:
- respiratory symptoms
- neurological : photophobia , seizures, drowsiness
- hemorrhagic rash or bleeding
- dense rash : with or without mucosal lesions
🚩high risk of complicated case;
- smoking
- chronic lung disease
- systemic steroids in the preceding 3 months
- IN THE 2nd HALF OF PREGNANCY
When should the woman with chickenpox be delivered?
Minimum of 7 days between the onset of the rash and delivery
What is the optimum method of anaesthesia in women with chickenpox requiring CS?
Epidural
-General anaesthesia: may exacerbate respiratory compromise
- spinal : risk of transmitting VZV to CNS
What are the risks to the fetus of varicella in pregnancy?
🚩If the woman develops varicella or shows serological conversion in the first 28 Days of pregnancy 👉 small risk of FVS
🚩there is no increase risk of miscarriage
How is FVS (fetal varicella syndrome) characterized?
1- skin scarring
2- eye defects: microophthalmia , chorioretinitis , cataracts
3- hypoplasia of the limbs
4- neurological abnormalities: microcephaly, cortical atrophy, mental retardation,
5- dysfunction of the bowel & bladder sphincters
Is FVS confined to cases of maternal infection in 1st trimester?
NO
there is an incidence after 20 w
Is there a way to prevent or ameliorate the risks to fetus of varicella infection?
Post exposure prophylaxis in susceptible pregnant women reduces the risk of developing FVS
Can varicella infection of the fetus be diagnosed prenatally?
1- US : at 16 - 20w OR 5 weeks after infection
2- MRI : if the US identified morphological abnormalities
3- amniocentesis: to detect VZV DNA by PCR [ has strong negative predictive value but poor positive predictive value]
When is the period that has a neonatal risk of varicella infection in pregnancy ?
If maternal infection occurs at the last 4 weeks of pregnancy there is a significant risk of varicella infection of the newborn
What are the routes of neonatal infection of varicella?
Trans placental / ascending vaginal
If maternal infection of varicella occurs 1 - 4 w before delivery how many babies will be infected?
Up to 50 % of the babies will be infected
23 % will devlop clinical varicella
What is the period of time that has the highest risk of developing severe neonatal chickenpox?
*If the infant is born within 7 days of the onset of the mother’s rash
* the mother develops rash up to 7 days after delivery
🔴👉 in that case the neonate should receive VZVIG prophylaxis as soon as possible with or without acyclovir
👉 delay delivery for at least 7 days after the onset of the rash
Is the maternal infection with chickenpox contraindicated for breastfeeding?
No they should breastfeed
