Epidemiology

Peak incidence: 6 months to 2 years

Etiology

Pathogen
- HHV-6 (and in rare cases HHV-7)
- Humans are the sole hosts.
Route of transmission: droplet infection (e.g., saliva)

Pathophysiology

Clinical features

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热退疹出，颜色粉红

Febrile phase

Duration: 3–5 days
Fever
- Abrupt onset of high fever, in some cases > 40ºC (104ºF)
- Febrile seizures are a potential complication of roseola (see “Complications” below).
Cervical, postauricular, and/or occipital lymphadenopathy
Inflamed tympanic membranes
Nagayama spots: papular enanthem on the uvula and soft palate

Exanthem phase

Duration: 1–3 days
Characteristic presentation: subsequent sudden decrease in temperature and development of a patchy, maculopapular exanthem
- Rose-pink in color; blanches upon pressure
- Nonpruritic (in contrast to the drug allergy rash)
- Originates on the trunk; sometimes spreads to the face and extremities

Diagnostics

Childhood exanthems

Feature Rubella (German Measles) Measles (Rubeola) Scarlet Fever Erythema Infectiosum (Fifth Dis.) Roseola Infantum (Sixth Dis.) Varicella (Chickenpox)
Agent Togavirus (RNA) Paramyxovirus (RNA) S. pyogenes (GAS) exotoxin Parvovirus B19 (DNA) HHV-6, HHV-7 (DNA) VZV (HHV-3) (DNA)
Prodrome Low-grade fever, postauricular/occipital LAD, arthralgias. 3 C’s: Cough, Coryza, Conjunctivitis. High fever. Fever, pharyngitis, headache, vomiting. Mild flu-like sx. High fever (>40°C) for 3-5 days, child appears well. Fever, malaise.
Enanthem Forchheimer spots (petechiae on soft palate) Koplik spots (blue-white spots on buccal mucosa). Pathognomonic. Strawberry tongue, palatal petechiae. N/A Nagayama spots (papules on soft palate). Ulcers in mouth/pharynx.
Exanthem Maculopapular rash starts on face, spreads caudally in <24h. Lighter than measles. Maculopapular rash starts at hairline, spreads caudally. Confluent. ”Sandpaper” texture, diffuse erythema. Starts on trunk, spreads out. Spares palms/soles. Circumoral pallor. ”Slapped cheeks” (malar rash), followed by lacy, reticular rash on trunk/extremities. Maculopapular rash appears as fever breaks. Starts on trunk, spreads to face/extremities. Vesicular rash on erythematous base (“dew drop on a rose petal”). Lesions in different stages. Starts on trunk, spreads to face/limbs.
Key Buzzwords ”3-day measles”, postauricular LAD. Congenital: PDA, cataracts, deafness. Koplik spots, 3 C’s, SSPE (late complication). Sandpaper rash, strawberry tongue, Pastia’s lines (linear petechiae in flexures). Slapped cheeks, aplastic crisis (in SCD), hydrops fetalis. Fever first, then rash. Febrile seizures common. Pruritic vesicles in crops, Tzanck smear shows multinucleated giant cells. Reactivates as shingles.
Tx Supportive. MMR vaccine for prevention. Supportive, Vit A. MMR vaccine for prevention. Penicillin or Amoxicillin (to prevent rheumatic fever). Supportive. Supportive. Supportive. Acyclovir in teens/adults/immunocompromised. Live-attenuated vaccine.

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Roseola infantum

Epidemiology

Etiology

Pathophysiology

Clinical features

Febrile phase

Exanthem phase

Diagnostics

Childhood exanthems

Treatment

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Table of Contents

Backlinks

Feature	Rubella (German Measles)	Measles (Rubeola)	Scarlet Fever	Erythema Infectiosum (Fifth Dis.)	Roseola Infantum (Sixth Dis.)	Varicella (Chickenpox)
Agent	Togavirus (RNA)	Paramyxovirus (RNA)	S. pyogenes (GAS) exotoxin	Parvovirus B19 (DNA)	HHV-6, HHV-7 (DNA)	VZV (HHV-3) (DNA)
Prodrome	Low-grade fever, postauricular/occipital LAD, arthralgias.	3 C’s: Cough, Coryza, Conjunctivitis. High fever.	Fever, pharyngitis, headache, vomiting.	Mild flu-like sx.	High fever (>40°C) for 3-5 days, child appears well.	Fever, malaise.
Enanthem	Forchheimer spots (petechiae on soft palate)	Koplik spots (blue-white spots on buccal mucosa). Pathognomonic.	Strawberry tongue, palatal petechiae.	N/A	Nagayama spots (papules on soft palate).	Ulcers in mouth/pharynx.
Exanthem	Maculopapular rash starts on face, spreads caudally in <24h. Lighter than measles.	Maculopapular rash starts at hairline, spreads caudally. Confluent.	”Sandpaper” texture, diffuse erythema. Starts on trunk, spreads out. Spares palms/soles. Circumoral pallor.	”Slapped cheeks” (malar rash), followed by lacy, reticular rash on trunk/extremities.	Maculopapular rash appears as fever breaks. Starts on trunk, spreads to face/extremities.	Vesicular rash on erythematous base (“dew drop on a rose petal”). Lesions in different stages. Starts on trunk, spreads to face/limbs.
Key Buzzwords	”3-day measles”, postauricular LAD. Congenital: PDA, cataracts, deafness.	Koplik spots, 3 C’s, SSPE (late complication).	Sandpaper rash, strawberry tongue, Pastia’s lines (linear petechiae in flexures).	Slapped cheeks, aplastic crisis (in SCD), hydrops fetalis.	Fever first, then rash. Febrile seizures common.	Pruritic vesicles in crops, Tzanck smear shows multinucleated giant cells. Reactivates as shingles.
Tx	Supportive. MMR vaccine for prevention.	Supportive, Vit A. MMR vaccine for prevention.	Penicillin or Amoxicillin (to prevent rheumatic fever).	Supportive.	Supportive.	Supportive. Acyclovir in teens/adults/immunocompromised. Live-attenuated vaccine.