Chickenpox (VZV)

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Chickenpox\: Common viral infection caused by the varicella-zoster virus (VZV); over 75% of children are infected by age

Transmission\: Via droplet spread or direct skin contact with vesicle
Incubation period\: Typically 10-14 days, can be up to 21 days.
Symptoms\: Acute disease with a vesicular rash, fever, and malaise; milder in younger children, more severe in adults.
Prodrome\: High fever (38-39°C), general malaise, myalgia, anorexia, headache, nausea (lasts up to 4 days).
Rash\: Starts as small erythematous macules, progresses to papules, vesicles, and pustules; itchy, can crust over in 5 days;
may include oral and genital ulcers.
Di
eruptions, dermatitis herpetiformis, insect bites.
Diagnosis\: Clinical diagnosis; lesion scrapings for con
Management\: Adequate hydration, avoid scratching, avoid high-risk individuals; paracetamol for fever, antihistamines,
emollients for itch; avoid NSAIDs.
High-risk groups\: Pregnant women, neonates, immunocompromised individuals; require specialist advice, antiviral
medication (aciclovir), intravenous immunoglobulin.
Complications\: Dehydration, secondary bacterial infection, scarring, viral pneumonia, encephalitis, Reye’s syndrome;
shingles as a later complication.
Prevention\: Noti
mass vaccination in the UK.
High-risk populations\: Pregnancy (risk of congenital varicella syndrome, neonatal herpes zoster, maternal pneumonia),
neonates (30% mortality from pneumonia or hepatitis), immunocompromised individuals (severe disseminated chickenpox).
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A comprehensive topic overview

Introduction

1
Chickenpox is a common viral infection, caused by the varicella-zoster virus (VZV). Over 75% of children are infected with
VZV before age
2

Aetiology

1
VZV is a DNA virus of the herpesviridae family. Transmission is via droplet spread or direct skin contact with vesicle
with the virus entering the body through the upper respiratory tract.
1,3

Clinical features

Chickenpox is an acute disease, characterised by a vesicular rash associated with fever and malaise. 3
period is typically 10-14 days but can be up to 21 days.
4
The incubationSymptoms are milder in younger children (once past the neonatal stage) and more severe in adults.
1
Prodrome
Prodromal symptoms can last up to four days and include the following\:
1,3
High fever (38-39°C)
General malaise
Myalgia
Anorexia
Headache
Nausea
Rash
As the prodromal period ends, the characteristic rash (Figures 1-3) develops\:
3
It begins as small erythematous macules on the scalp, face, trunk and proximal limbs
These macules develop into papules, vesicles and pustules which appear in crops
Vesicles may be found on the palms, soles and mucous membranes, and are especially itchy
Shallow oral and genital ulcers can also occur, which are painful
Crusting of the vesicles and pustules usually occurs in
Figure 1. A child with chickenpox – you can see the crops of lesions at di
9Figure 2. A baby with chickenpox – the lesions usually start on the scalp and face.
10
Figure 3. A child with chickenpox – with papules, vesicles and crusted lesions visible.
11

Di

There are several di
3
Table 1.Di
Di
Vesicular viral rashes Herpes simplex (HSV)
Vesicles are usually more
localised i.e. cold sores (except in
eczema herpeticum-
disseminated HSV)Herpes zoster (VZV)
Hand, foot and mouth
disease (Coxsackie A
virus)
Other infections
Impetigo (usually
strep or staph)
Scabies (mites)
Also known as shingles - a
reactivation of VZV usually
localised to a unilateral
dermatome
This rash presents as vesicles
localised to the hands and feet,
with ulcers in the mouth
Pustules which develop into
golden crusted lesions, usually
on the face
Erythematous papular
rash usually starting between the

Skin disorders
Guttate psoriasis, drug
eruptions, dermatitis
herpetiform, insect
bites

Investigations

Chickenpox is a clinical diagnosis, and investigations are not generally required unless there are concerns about
complications. If diagnostic con
1

Management

General advice1
General advice to prevent complications and the spread of the virus includes\:
Adequate hydration
Avoidance of scratching (due to the risk of infection and scarring)
Avoidance of pregnant women, neonates and immunocompromised individuals
Symptomatic management
Symptomatic management options include\:
Paracetamol for fever and discomfort
3
NSAIDs should be avoided as they increase the risk of necrotising soft tissue infections
5
Sedating antihistamines (chlorphenamine), emollients and calamine lotion for itch
1,3
If an adolescent or adult presents within 24 hours of rash onset (especially if severe or they are at high risk of
complications) oral aciclovir can be considered
3
Treatment in high-risk groups
Management di
due to the increased risk of severe disease.
Urgent specialist advice should be sought and further management options may include\:
Antiviral medication such as aciclovir
Intravenous immunoglobulin (typically for individuals who have not previously been exposed to varicella-zoster virus)
Treatment of complications
1Secondary bacterial skin infection and pneumonia require antibiotics. Hospital admission is likely to be necessary for
those with severe disease or complications.Public health requirements
Chickenpox is a noti1
return to school until all lesions are crusted over, due to the highly infectious nature of the virus. 6
the UK, but there is no mass vaccination programme.
1
Children should not
A vaccine is available in

Complications

In healthy children, chickenpox is usually self-limiting. 3
high-risk groups\:
1
However, complications occur more frequently in the following
Immunocompromised patients (e.g. cancer patients on chemotherapy)
Very young (neonates) or older patients
Pregnant women\: causes both more severe maternal disease and fetal complications (discussed below)
Complications may include\:
Dehydration
3
Secondary bacterial infection of lesions
1
Scarring
1
Viral pneumonia\: this is more common in older children and adults and can be life-threatening
1
Encephalitis\: the associated mortality is 5-10%
1
Reye’s syndrome\: a very rare condition seen in children and young adults recovering from viral illnesses. It is thought to
be related to the use of aspirin, which should be avoided in children
7
Once a person has had chickenpox they are usually immune if immunocompetent, with second episodes thought to be
1
rare.
Shingles
The VZV virus remains dormant in the sensory nerve ganglia of the dorsal root and can reactivate as herpes zoster
(shingles) many years later.
3

High-risk populations

Chickenpox in pregnancy
If chickenpox is contracted before 20 weeks gestation there is a \<2% risk of congenital varicella syndrome. 8
characterised by\:
1
This is
Intrauterine growth restriction
Microcephaly
Limb hypoplasia
Ophthalmological defects
Cutaneous scarring
After 20 weeks gestation, maternal chickenpox infection can cause neonatal herpes zoster (shingles) or preterm
labour. 1 1
Maternal chickenpox can also be severe, with a high risk of pneumonia for the mother.
Chickenpox in neonates
There is a risk of neonatal chickenpox if the maternal rash appears seven days before, to two days after delivery (as there
is transplacental transmission of the virus but not the initial IgM antibodies). 1
Neonatal chickenpox has a 30% mortality,
1 1
usually from severe pneumonia or fulminant hepatitis. Treatment is with aciclovir and immunoglobulin.
Chickenpox in immunocompromised individuals
There is a greater risk of severe disseminated chickenpox, varicella pneumonia, encephalitis, hepatitis, and haemorrhagic
complications amongst immunocompromised individuals.
3References
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Reviewer

Dr Jennifer Mackintosh
Paediatrics ST8

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