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HKCEM College Tutorial
Chickenpox
Author
Dr. Shek Kam Chuen
Oct 2013
Case history
▪ F/3, come with her aunt
▪ Presented to AED for fever 38oC & vesicular rash
for one days
▪ “?” cubicle
▪ nil contact, nil ILI symptom
Fever with rash
Very Sick People Must Take No Exercise
▪ DDX
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▪
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Varicella/viral rash
Infectious mononucleosis
Dengue fever
Meningococcal disease
Drug rash, Still’s disease
Kawasaki’s syndrome: Polymorphous rash 5 Ds after fever
Diagnosis
▪ 1. Smallpox
▪ 2. Herpes zoster
▪ 3. Bullous pemphigoid
▪ 4. Bullous impetigo
▪ 5. Chickenpox
Chickenpox Rash
▪ Initially maculopapular, then vesicles,clear fluid
▪ Begins on face & trunk then centripetally
▪ Vesicle are round with erythematous base
▪ Crust
▪ All form of lesions are concurrently present
Smallpox
▪ Early Rash(Duration: about 4 days)
▪ starting on the face and spreading to the
arms and legs and then to the hands and
feet.
▪ Pustular Rash
▪ BB pellets embedded in the skin
▪ last naturally occurring case in the world was
in Somalia in 1977.
Her aunt claimed that patient also pain on urination
▪ P/E>>Vesicular Vulval Rash>>?Genital herpes
▪ What is your action?
▪ 1. Refer to SHS service
▪ 2. Admit Paed as STD suspected (?abuse)
▪ 3. Give acyclovir cream for symptomatic relief
▪ 4. Re-assurance
Most Diagnosis are clinical
▪ Laboratory Criteria (Any one of the following)
▪ Isolation of varicella zoster virus (VZV) from
clinical specimens
▪ Demonstration of a ≥4x rise in antibody (Ab)
titre
▪ Demonstration of viral antigen in vescular fluid
or scrapings using fluorescent-Ab staining
▪ Positive PCR for VZV in clinical specimens
HA Central Committee on Infectious Disease and Emergency Responses (CCIDER)
Guideline on Varicella Zoster Virus Infections 22 May 2012
Chickenpox
▪ Modes of transmisson: Contact, Droplets, airborne
▪ Incubation periods:
▪ 10-21 days
▪ Can be prolonged to 28 days in
immunocompromised patients and recipients of
Varicella-Zoster IG
Period of communicability:
▪ 2 days before onset of rash and continue until all
lesions are crusted
▪ (usually within 1week from onset of rash).
You noticed
▪ His aunt is pregnant, 35wks.
▪ What is your action?
▪ 1. Do nothing
▪ 2. advice chickenpox vaccination by GP as
HA will not provide chickenpox vaccination
▪ 3. offer acyclovir PEP
▪ 4. enquire her chickenpox status
Definition of susceptibility
▪ Individuals are considered susceptible if they DO NOT
fulfill any one of the following:
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History of chickenpox/herpes zoster
History of varicella vaccination completed according
to recommended schedule
Positive VZV IgG serology
Neonates (except preterm < 28 weeks or birth weight
≤1000g) born to immune mothers are protected by
maternal antibody. Protection may be up to 6 months.
Serological test is recommended in case of doubt
Chickenpox Status
▪ Childhood infectious disease
▪ >95% adult are infected in childhood
▪ Ask patient’s mother
▪ In case of any doubt, pls do urgent varicella IgG test.
▪ Inform ICN to arrange an urgent test
▪ Enter the CMS that the quarantine period
▪ Advice patients not to attend antenatal clinic and must
inform O&G MO when admitted for labour.
▪ Arrange FU in 96 hrs
Management flowchart for susceptible pregnant
women with chickenpox exposure.
HKJEM 2009;01:46
Chickenpox in Pregnancy 1
▪ Maternal risks
▪ In pre-antiviral era, mortality up to 25%
▪ Chickenpox pneumonia can be up to 10%
▪ Neonatal risks:
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2% of Congenital Varicellar Infection if < 20 weeks.
Skin contracture, scarring, limb hypoplasia
Eye, cataract
16-29% MR, microcephaly
Chickenpox in Pregnancy 2
▪ Between 20 to 36 wks
▪ No associated fetal effect
▪ Many child present with zoster in first few year.
Chickenpox in Pregnancy 3
▪ > 36 weeks
▪ Likely to infect the baby
▪ Neonatal chickenpox
VZV in Pregnancy
18
Chickenpox in Pregnancy 4
▪ Treatment acyclovir if within one days of rash and more than 20
weeks of gestation
▪ Informed consent for acyclovir
▪ VZVIG no effect if already rash develop
Chickenpox status
▪ If IgG positive>>
▪ If IgG intermediate>>pending confirmation test by virus unit
▪ If IgG –ve>>
▪ What is your action?
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1. Quarantine 10-21days after last exposure
2. Chickenpox immunization
3. Acyclovir daily till delivery
4. VZVIg IMI
VZIG
▪ Within 96hr after exposure
▪ May prevent or attenuate infection
▪ Limited data suggest that attenuation of disease might be
achieved with VZIG up to 10 days after exposure.
▪ Not useful if chickenpox rash already develop
▪ Incubation period may prolong to 28 days
VZIG
▪ IM VZIG is indicated and should be administered within 96 hours
post-exposure for following high risk groups:
▪ Immunocompromised person
▪ Pregnant woman
▪ Neonates whose mothers have signs and symptoms of varicella
around the time of delivery (i.e., 5 days before to 2 days after).
▪ Preterm infant <28 wk or birth weight ≤1000g exposed during
neonatal period.
▪ Preterm infant (≥28 wk) exposed during neonatal period and
whose mother do not have evidence of immunity to VZV.
Other PEP to consider
▪ VZV vaccination
▪ As PEP within 5d of exposure for immunocompetent non-pregnant
contacts >12 months of age
▪ Acyclovir
▪ As PEP within 10d post exposure.
▪ No clear recommendation
Her aunt at follow up clinic
▪ VZV IgG was +ve, now 38 week
▪ However, she develop herpes zoster over the left chest
wall.
▪ What is your action?
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▪
▪
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Admit to isolation ward?
VZIG to mother to prevent neonatal chickenpox
VZIG to new born to prevent neonatal chickenpox
Acyclovir
▪ Acyclovir is a FDA category B, no teratogenic effect
A 32 wks pregnant
triage nurse exposed to the chickenpox
▪ Contact tracing
▪ no history of chickenpox
▪ Urgent blood for IgG >> -ve
▪ Need for PEP?
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▪
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1. VZIG
2. Long term Acyclovir till birth
3. Immediate immunization
4. Is it a significant exposure?
Significant exposure
▪ Definition of significant contact (any one):
▪ Continuous household contact,
▪ face to face contact > 5min,
▪ or conversation,
▪ Stay in the same room/cubicle for >15 min,
Tang CL, et al. Hong Kong J Emerg Med. 2009;16:46-50
End
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