Erythema Infectiosum

Basics

Characteristic viral exanthem also known as fifth disease:
- Fifth most common childhood rash historically described
- Measles (first), scarlet fever (second), rubella (third), Duke disease (fourth), roseola (sixth)
Common symptoms:
- Viral prodrome
- Followed by slapped-cheek rash
- Then subsequent diffuse reticular rash +/− arthropathy
Most common in school-aged children <14 yr
Usually self-limited with lasting immunity
Rare complications and chronic cases in patients with congenital anemias or immunosuppression
Potential for severe complications to fetus if infection acquired during pregnancy
Possible link to encephalopathy, epilepsy, meningitis, myocarditis, dilated cardiomyopathy, autoimmune hepatitis, HSP, ITP

Caused by human parvovirus B19, small SS-DNA virus:
- Infects human erythroid progenitor cells, suppressing erythropoiesis
Most common in late winter and spring
Transmitted via respiratory droplets and blood products as well as vertical maternal–fetal transmission
Incubation period 4–21 d
Most contagious during the week PRIOR to rash onset
Majority of adults have serologic evidence of prior infection

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