Viral Exanthema

Question 1

What are the causes of viral exanthema in children

Answer 1

Herpes simplex virus
Parvovirus B19 (slapped cheek/fifth disease)
Hand, foot, and mouth disease
Varicella zoster
Measles
Rubella
Molluscum contagiosum
Roseola infantum (HHV-6)
(Infectious mononucleosis)

Question 2

What is eczema herperticum and what are the clinical features

Answer 2

Secondary infection of skin affected by eczema with herpes simplex virus (HSV)

S/S:
clusters of blisters consistent with early cold sores
“punched out” lesions (circular, depressed, ulcerated)

Question 3

What is the treatment for eczema herpeticum

Answer 3

Aciclovir (oral or IV)

Bacterial infection: systemic ABx
Refer to Ophthalmology if any lesions near the eye to exclude ophthalmic herpeticum due to risk of scarring

Question 4

What is erythema multiforme and what is the most common causes

Answer 4

Type IV hypersensitivity reaction presenting with skin rash

• Herpes simplex virus
• Mycoplasma pneumoniae
• Medications
• Autoimmune disease
• Sarcoidosis

Question 5

What are the clinical features of erythema multiforme

Answer 5

Target-like lesions
- Starts as a red maculae and develops into target lesions 24h later
- 1-3cm
- Arises abruptly in successive crops over 3-5 days
- Upper > lower limbs
- May progress to bullae

EM Major: Haemorrhagic crusting of lips

Question 6

What is the management for erythema multiforme

Answer 6

Usually self-limiting - no treatment needed

HSV → Aciclovir

Pruritis → Antihistamines and corticosteroids

If drug is causative → withdraw

Severe → admit + IV hydration + skin care

Question 7

What is the cause of slapped cheek syndrome and what are the risk factors

Answer 7

Parvovirus B19, usually in outbreaks among school-aged children

RF: haemoglobinopathies, immunosuppression

Question 8

What are the signs and symptoms of parvovirus B19 infection

Answer 8

Prodrome for 2-3 days: fever, coryza, headache, N&V
(Latent for 7-10 days)

Rash:
- Malar rash with circumoral pallor (perioral sparing)
- Very hot to touch
- Followed by a lace-like rash on the trunk and extremities

Aplastic crisis – occurs in children with chronic haemolytic anaemia (sickle cell) or immunodeficient
Fetal disease – maternal transmission – leads to fetal hydrops, death due to severe anaemia

Question 9

What investigations should be done for suspected parvovirus B19

Answer 9

Clinical diagnosis

Can confirm with blood tests:
- Parvovirus serology (IgG, IgM)
- Parvovirus RT-PCR

Question 10

What is the management for Parvovirus B19

Answer 10

Supportive (self-limiting) - the rash usually peaks after a week and then fades
- Re-assure
- Emollients
- Ice-cold flannel to relieve discomfort/burning cheeks

NO school exclusion required
Safety net: anaemia, lethargy, pregnancy

Question 11

What is hand, foot, and mouth disease and what is the cause

Answer 11

Acute viral infection caused by enteroviruses

Enteroviruses: most commonly coxsackievirus A16
Otherwise enterovirus A71 (severe)
Highly infectious - several close contacts may be affected (outbreak)

Question 12

What are the signs and symptoms of Hand, foot, and mouth disease

Answer 12

Macular, maculopapular or vesicular exanthema on hands, feet, buttocks, legs, arms
Oral vesicles that rupture to form ulcers on the tongue and buccal mucosa (enanthem): Peel off within a week, Grey in colour
Fever
Sore throat
Loss of appetite
Malaise
Mild diarrhoea

Question 13

What are the investigations and management for hand, foot, and mouth disease

Answer 13

Clinical diagnosis
(If any travel to South East Asia, Canada or America consider throat swab and EDTA serology for typing as causes more severe illness)

Supportive
(resolves within 7 days)
- Analgesia
- Difflam spray
- Hand hygiene

No school exclusion required

Question 14

What is molluscum contagiosum caused by and what are the risk factors for infection

Answer 14

Caused by Poxvirus

Predominantly affects children

Risk Factors:
- Close contact with infected individual (children)
- Sexual contact with an infected individual
- HIV infection
- Tropical climate
- Swimming
- Atopic dermatitis

Question 15

What are the signs and symptoms of molluscum contagiosum

Answer 15

Flesh-coloured, pearly, dome-shaped papules on the skin
- Painless, pruritic
- 2-5mm
- Central umbilication/dell and shiny surface
- Occurs in crops
- >50 lesions suggests immunosuppression
Surrounding erythema
Atopic dermatitis
Pruritus, difficulty sleeping

Question 16

What investigations and management is indicated for molluscum contagiosum

Answer 16

Clinical diagnosis
If widespread → consider HIV testing
Haematoxylin and eosin staining (Henderson-Patterson bodies)

Self resolving - no treatment indicated
Lasts 18 months
Warn that they become red/visible inflamed before improving
Lesions are facial/in sensitive or obvious areas/ bullying involved → refer to Derm

Question 17

What causes varicella zoster and describe its transmission

Answer 17

Varicella zoster virus (HHv-3) – reactivation of dormant virus after chickenpox leads to herpes zoster (shingles)

Direct contact with lesions or respiratory aerosol droplets
Incubation period = 10-21 days
Infectious period = 48 hours before rash to last crusted over lesion / 5-7 days after rash appears

Question 18

What are the symptoms and signs of varicella zoster

Answer 18

Crops of vesicles appear over 3-5 days:
- Head, neck, trunk (less on limbs) – itchy
- Macule → Papule → vesicle → crust – several stages at once
Pyrexia, headache, abdominal pain, malaise

Question 19

What investigations and management should be done for varicella zoster

Answer 19

Clinical diagnosis

Supportive (virus; fluids, analgesia (no ibuprofen), rest)
Advice – nails short, loose clothing, infectious period = 1-2 days before rash to last crusted over lesion
School exclusion until lesions have crusted over
Isolate from immunocompromised people, pregnant women, neonates

Question 20

What are the complications of varicella zoster

Answer 20

Pneumonia
Secondary bacterial superinfection → sudden high fever: toxic shock, necrotising fasciitis
Encephalitis (cerebellar ataxia; better prognosis than HSV-encephalitis)
Purpura fulminans: large necrotic loss of skin from cross-activation of antiviral ABs → inhibit the inhibitory coagulation proteins factors C and S → increased clotting and purpuric skin rash
Dehydration (severe)
Transient arthritis

Question 21

What is the management for varicella zoster in the following situations: serious complications, immunocompetent adolescents/adults, immunocompromised children

Answer 21

Serious complications: admit if serious complications
Immunocompetent adolescents/adults: oral aciclovir 800 mg 5/day for 7 days (if <24hrs of rash)
Immunocompromised children: IV aciclovir →oral aciclovir

Prophylactic prevention = human VZV IVIG

Question 22

Why might infectious mononucleosis cause a rash

Answer 22

Treatment with penicillin while infected

Question 23

What causes roseola infantum, how is it transmitted and what age group does it affect

Answer 23

Human Herpesvirus 6 (HHV-6)
Incubation period of 5-15 days, highly infectious
6 months - 2years

Question 24

What are the signs and symptoms of roseola infantum

Answer 24

Prodrome: High fever and malaise (3-4 days)
Generalised macular (small pink spots) rash (appears as the fever wanes)
- Starts on neck/body and spread to arms, lasting
- 1-2 days, non-itchy, blanching
Sore throat
Lymphadenopathy
Coryzal symptoms
D&V
Nagayama spots (spots on the uvula and soft palate)

(Many have a febrile illness and never develop a rash; commonly misdiagnosed as measles/rubella - Febrile convulsions in 10-15%)

Question 25

What investigations should be done for roseola infantum

Answer 25

HHV6/7 serology (IgG and IgM)
Measles & rubella serology (similar presentation)

Question 26

What is the management for roseola infantum

Answer 26

Supportive (virus; fluids, analgesia, rest)
Will clear in ~1 week
No need to stay off school
Safety net the complications – high fever (febrile convulsions 10-15%)