The only single-stranded DNA (ssDNA) virus!

Pathophysiology

Parvovirus B19 binds to the P antigen (globoside) on erythroid progenitor cells → cellular invasion → viral DNA enters the nucleus of erythroid cells → viral DNA replication → cytotoxicity → clinical manifestations + transient cessation of erythropoiesis

Clinical features

Mild respiratory symptoms
Rash
- Erythema infectiosum (fifth disease)
Parvovirus B19-associated arthritis
Severe anemia or transient aplastic crisis
Hydrops fetalis
- Parvovirus B19 is a TORCH infection that can cause fetal death and miscarriage.

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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Parvovirus B19

Pathophysiology

Clinical features

Childhood exanthems

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Table of Contents

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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.