Viral Exanthema Flashcards
What are the causes of viral exanthema in children
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)
What is eczema herperticum and what are the clinical features
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)
What is the treatment for eczema herpeticum
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
What is erythema multiforme and what is the most common causes
Type IV hypersensitivity reaction presenting with skin rash
- Herpes simplex virus
- Mycoplasma pneumoniae
- Medications
- Autoimmune disease
- Sarcoidosis
What are the clinical features of erythema multiforme
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
What is the management for erythema multiforme
Usually self-limiting - no treatment needed
HSV → Aciclovir
Pruritis → Antihistamines and corticosteroids
If drug is causative → withdraw
Severe → admit + IV hydration + skin care
What is the cause of slapped cheek syndrome and what are the risk factors
Parvovirus B19, usually in outbreaks among school-aged children
RF: haemoglobinopathies, immunosuppression
What are the signs and symptoms of parvovirus B19 infection
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
What investigations should be done for suspected parvovirus B19
Clinical diagnosis
Can confirm with blood tests:
- Parvovirus serology (IgG, IgM)
- Parvovirus RT-PCR
What is the management for Parvovirus B19
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
What is hand, foot, and mouth disease and what is the cause
Acute viral infection caused by enteroviruses
Enteroviruses: most commonly coxsackievirus A16
Otherwise enterovirus A71 (severe)
Highly infectious - several close contacts may be affected (outbreak)
What are the signs and symptoms of Hand, foot, and mouth disease
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
What are the investigations and management for hand, foot, and mouth disease
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
What is molluscum contagiosum caused by and what are the risk factors for infection
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
What are the signs and symptoms of molluscum contagiosum
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
What investigations and management is indicated for molluscum contagiosum
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
What causes varicella zoster and describe its transmission
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
What are the symptoms and signs of varicella zoster
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
What investigations and management should be done for varicella zoster
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
What are the complications of varicella zoster
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
What is the management for varicella zoster in the following situations: serious complications, immunocompetent adolescents/adults, immunocompromised children
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
Why might infectious mononucleosis cause a rash
Treatment with penicillin while infected
What causes roseola infantum, how is it transmitted and what age group does it affect
Human Herpesvirus 6 (HHV-6)
Incubation period of 5-15 days, highly infectious
6 months - 2years
What are the signs and symptoms of roseola infantum
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%)
What investigations should be done for roseola infantum
HHV6/7 serology (IgG and IgM)
Measles & rubella serology (similar presentation)
What is the management for roseola infantum
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%)
