Clinical findings

Impetigo starts as a small, thin-walled vesicle that bursts quickly, leaving an exudate that dries to form a thick yellowish (honey-coloured) or brown crust – often described as looking like stuck-on cornflakes.

Lesions typically appear on the face, round the mouth or nose, but can also occur elsewhere on the body (e.g. axillae, trunk). Lesions often occur in clusters and can coalesce. Satellite lesions can develop as a result of autoinoculation from scratching or touching of the original lesions.

The crusts dry and heal without scarring over two to three weeks. There may be residual redness that fades over days or weeks. If there is damaged skin (e.g. due to eczema, scabies, insect bites (including headlice)), impetigo may become more widespread as the damaged skin provides a portal for entry of bacteria.

The main risk factors for impetigo are young age (under five years), contact with other cases and crowded living or work conditions. The diagnosis is usually based on the clinical appearance and history.