Viral Exanthema Flashcards

1
Q

What are the causes of viral exanthema in children

A

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)

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2
Q

What is eczema herperticum and what are the clinical features

A

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)

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3
Q

What is the treatment for eczema herpeticum

A

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

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4
Q

What is erythema multiforme and what is the most common causes

A

Type IV hypersensitivity reaction presenting with skin rash

  • Herpes simplex virus
  • Mycoplasma pneumoniae
  • Medications
  • Autoimmune disease
  • Sarcoidosis
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5
Q

What are the clinical features of erythema multiforme

A

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

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6
Q

What is the management for erythema multiforme

A

Usually self-limiting - no treatment needed

HSV → Aciclovir

Pruritis → Antihistamines and corticosteroids

If drug is causative → withdraw

Severe → admit + IV hydration + skin care

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7
Q

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

A

Parvovirus B19, usually in outbreaks among school-aged children

RF: haemoglobinopathies, immunosuppression

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8
Q

What are the signs and symptoms of parvovirus B19 infection

A

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

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9
Q

What investigations should be done for suspected parvovirus B19

A

Clinical diagnosis

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

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10
Q

What is the management for Parvovirus B19

A

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

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11
Q

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

A

Acute viral infection caused by enteroviruses

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

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12
Q

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

A

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

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13
Q

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

A

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

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14
Q

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

A

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

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15
Q

What are the signs and symptoms of molluscum contagiosum

A

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

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16
Q

What investigations and management is indicated for molluscum contagiosum

A

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

17
Q

What causes varicella zoster and describe its transmission

A

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

18
Q

What are the symptoms and signs of varicella zoster

A

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

19
Q

What investigations and management should be done for varicella zoster

A

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

20
Q

What are the complications of varicella zoster

A

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

21
Q

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

A

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

22
Q

Why might infectious mononucleosis cause a rash

A

Treatment with penicillin while infected

23
Q

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

A

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

24
Q

What are the signs and symptoms of roseola infantum

A

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%)

25
Q

What investigations should be done for roseola infantum

A

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

26
Q

What is the management for roseola infantum

A

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%)