Acute viral exanthems

Acute rashes are a common medical problem in primary and secondary care. Approximately 5% of both paediatric and adult presentations to emergency departments are because of a rash illness. Fever, rash, headache and malaise are common features of many viral infections. Typically, rashes of infective aetiology can be divided into four categories: maculopapular, vesicular, papular/purpuric and other infectious immune-associated erythematous rash presentations. Although the early morphological features of viral rashes can appear similar, they differ in their character, evolution and accompanying associated clinical features. The serious but uncommon adverse complications of infections inducing viral exanthems increase their clinical and public health importance. Further diagnostic support through testing can be done by swabbing lesions using polymerase chain reaction (PCR) methods for direct virus genome detection in the early stages, or by viral serology to detect specific immunoglobulin (Ig) G and IgM responses in the later stages of infection. The use of these syndromic descriptions in the identification of virus illnesses recognizes the similarities between these diseases but helps to limit the differential diagnostic range of viral infections causing an erythematous rash and focus diagnostic testing and management interventions (where available) more appropriately.