Child health · UKMLA & AKT
Erythema infectiosum (Fifth disease/Parvovirus B19)
A free high-yield preview for the UKMLA Applied Knowledge Test. Below are the key points to recognise erythema infectiosum (fifth disease/parvovirus b19) — the full SA Note notes add investigations, management, complications and 10 practice questions.
Key high-yield points
- Prodrome (infectious phase): low-grade fever, coryzal symptoms, headache, myalgia - child is contagious here, NOT when the rash appears
- 'Slapped cheek' rash: bright red confluent erythema over both cheeks with perioral pallor - appears once child is afebrile and recovering
- Lacy reticular rash: pink net-like maculopapular rash on trunk and limbs, 1-4 days after facial rash; blanching, non-pruritic; may recrudesce with heat/exercise for weeks
- Adults: slapped cheek often absent; dominant feature is symmetrical polyarthropathy (hands, wrists, knees) - can mimic rheumatoid arthritis
The rash is immune-mediated (not direct viral effect) - this is why the child is no longer viraemic and no longer infectious once the rash appears.
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