🩸 TOACS FCPS Station · Erythema Infectiosum (Parvovirus B19)
📷 Clinical Photograph – Erythema Infectiosum
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🔍 Key clinical features:
- ✓ 'Slapped cheek' rash – bright red, confluent on both cheeks
- ✓ Lacy reticular rash – on trunk and extremities, may wax and wane
- ✓ Prodrome – mild fever, malaise, headache (before rash)
- ✓ Self-limited – resolves without treatment
- ✓ Not contagious after rash appears – contagious during prodrome
📋 Clinical scenario (examiner prompt)
A 6‑year‑old child is brought in with a bright red rash on the cheeks that started yesterday. The child had mild fever, runny nose, and headache a few days ago. The rash is now lacy and reticular on the trunk and extremities. The child is afebrile and well-appearing. The mother is concerned because the rash worsens with sunlight and heat. The child attends school and has no known sick contacts.
🧑⚕️ Examiner tasks · TOACS
1. Identify the diagnosis from the clinical image and context.
2. Describe the clinical features (slapped cheek, lacy reticular rash, prodrome, waxing/waning).
3. Explain the etiology and transmission (parvovirus B19, respiratory droplets, contagious before rash).
4. Discuss management, complications, and prevention (supportive care, aplastic crisis in sickle cell, hydrops fetalis in pregnancy).
🎯 Expected answers (for examiners)
- • Diagnosis: Erythema infectiosum (Fifth disease, parvovirus B19)
- • Clinical features: 'Slapped cheek' rash (bright red, confluent on cheeks), then lacy reticular rash on trunk/extremities. Prodrome of mild fever, headache, malaise. Rash may wax and wane with heat, sun, exercise.
- • Etiology: Parvovirus B19 (single-stranded DNA virus, infects erythroid progenitor cells)
- • Transmission: Respiratory droplets, contagious during prodromal phase (before rash)
- • Diagnosis: Clinical; if needed, parvovirus B19 IgM (acute) or PCR
- • Treatment: Supportive care (analgesics, antipyretics, hydration)
- • Complications: Transient aplastic crisis (chronic hemolytic anemia), arthropathy (adults), hydrops fetalis (pregnancy)
- • Prevention: Hand hygiene; no vaccine
• Classic rash: 'Slapped cheek' → lacy reticular (trunk/extremities)
• Not contagious after rash appears – can return to school/daycare
• High-risk groups: Sickle cell (aplastic crisis), pregnant women (hydrops), immunocompromised (chronic anemia)
• Diagnosis: Clinical; serology (IgM) or PCR if needed
• Treatment: Supportive care only
⚡ Quick FCPS‑style MCQ
A child presents with bright red cheeks and a lacy reticular rash on the trunk and extremities after a mild febrile illness. The most likely diagnosis is:
A. Measles B. Erythema infectiosum (parvovirus B19) C. Scarlet fever D. Roseola📌 Topic summary · Erythema Infectiosum (Parvovirus B19)
Parvovirus B19
'Slapped cheek' → lacy reticular
Prodrome (before rash); NOT after rash
Supportive care
Aplastic crisis (sickle cell), hydrops (pregnancy), arthropathy
Hand hygiene; no vaccine
| Feature | Erythema Infectiosum |
|---|---|
| Virus | Parvovirus B19 |
| Transmission | Respiratory droplets |
| Rash | 'Slapped cheek' (bright red cheeks) → lacy reticular on trunk/extremities |
| Contagious period | Prodromal phase (before rash); NOT after rash appears |
| Complications | Transient aplastic crisis (chronic hemolytic anemia), arthropathy (adults), hydrops fetalis (pregnancy) |
| Diagnosis | Clinical; parvovirus B19 IgM or PCR if needed |
| Treatment | Supportive care (no antiviral) |