Viral Childhood Exanthems Flashcards
1
Q
HHV-6 & HHV-7
A
Viral Childhood Exanthems
• Ubiquitous; most infected by 2 years-old (HHV-6) or 3 years-old (HHV-7)
• Transmission by oral secretions
• Virus replication in oropharynx, B cells & T cells
• Cause *roseola infantum
2
Q
Measles Virus
A
Viral Childhood Exanthems Paramyxoviridae • Single-stranded, negative-stranded linear RNA genome • Helical. Large (150 nm) • Enveloped, spherical • Replicates in the cytoplasm - causes *MEASLES (*rubeola) 2 Glycoproteins – *Hemagglutinin – *F (fusion) protein
3
Q
Parvovirus B19
A
Viral Childhood Exanthems Parvoviridae • Single-stranded, linear DNA genome • Icosahedral • Naked (non-enveloped) • Small (18-26 nm) • Replicates in the nucleus • Transmission from Respiratory secretions, Congenitally, Blood transfusion, Fomites • Only infects humans • Only one serotype • No vaccine! DISEASE • *Erythema infectiosum – Fifth disease – *“Slapped cheek” syndrome • Transient aplastic crisis • Chronic anemia • Fetal death or non-immune hydrops fetalis
4
Q
Rubella virus
A
Viral Childhood Exanthems Togaviridae • Single-stranded, positive-sense linear RNA genome • Icosahedral, Medium (65-70 nm) • Enveloped, spherical • Replicates in the cytoplasm • Includes Rubella virus, Chikungunya virus • Only reservoir is humans • Transmission by respiratory secretions or congenitally • Only one serotype • Prevention by live, attenuated vaccine DISEASE • *German measles • *Congenital Rubella Syndrome (CRS)
5
Q
Varicella – Zoster Virus
A
Viral Childhood Exanthems Herpesviridae • Double-stranded, linear DNA genome • Icosahedral • Enveloped, spherical to pleomorphic • Large (150-200 nm) • Replicate in the nucleus • Have their own *DNA polymerase DISEASE • *Chickenpox, also called *varicella, is a mild, self-limited illness in healthy children, but it can occasionally lead to serious morbidity. • VZV also causes *shingles which is also called *herpes zoster due to reactivation of latent VZV, usually in elderly & people who have compromised cellular immunity.
