Acute viral exanthems

Exanthems/rashes are common in childhood and account for a large number of consultations in primary care and attendances to the emergency department. They are typically caused by allergic reactions, by viruses and occasionally by severe life-threatening bacterial infections. A careful history (including prodrome, associated symptoms, exposure to infectious contact, foreign travel, animals and immunization status), examination of the rash (including distribution, morphology, nature and site) and generalized examination (including presence of conjunctivitis, genital lesions, enanthems, hepatosplenomegaly and lymphadenopathy) can inform diagnosis. Molecular testing has led to a cause being identified in approximately 50% of cases. Early diagnosis is particularly important in the context of severe systemic infection, in immunocompromised hosts and in pregnancy. This review outlines the most common infectious exanthems, including measles, rubella, varicella, erythema infectiosum, roseola infantum and enterovirus infection.