Viral Exanthema Flashcards
What are the causes of viral exanthema
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)
(Zika virus
Dengues virus
West Nile virus)
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
Why might infectious mononucleosis cause a rash
Treatment with penicillin while infected
