Exanthem 5: parvovirus
Parvovirus B19 induces immune complex formations that deposit in joints and the skin, causing ‘erythema infectiosum’. It also infects the erythroblas-toid precursors in the bone marrow. The infection occurs in all ages and is more common in the winter and spring.
• Prodrome: infection spread by respiratory secretions and droplets. Then low-grade fever, headache, and coryza 7 days after exposure.
• Exanthematous phase: a number of days; bright red macules on the face with a ‘slapped-cheek’ appearance, (also, peri-oral pallor). The rash spreads to the limbs sparing the palms and soles. It is more intense with exposure to sunlight, heat, exercise, and stress.
• Other features: other patterns of illness include asymptomatic infection, aplastic crisis, foetal hydrops (from maternal infection).
• Clinical: characteristic rash.
• Serology: if the diagnosis is in question titres can be measured.
Management is supportive: antipyretics for fever.