What is Kawasaki disease and who gets it?Kawasaki disease is an acute febrile illness of early childhood, with about 80% of cases occurring between 6 months and 5 years. It is characterised by fever lasting at least five days and a constellation of clinical features that are used as diagnostic criteria (box 1). The clinical features are similar in all ethnic groups.2 Kawasaki disease is an acute inflammatory vasculitis of medium sized elastic arteries that has a striking propensity to damage the coronary arteries. As a consequence, it is the leading cause of acquired heart disease in children in developed countries.Box 1 Clinical diagnostic criteriaFever of at least five days’ duration and at least four of the following five clinical features: Polymorphous exanthema (but not petechial, bullous, or vesicular lesions) Bilateral non-exudative conjunctival injection Changes in lips and oral cavity (but not discrete oral lesions or exudates) Changes in the extremities, including erythema or indurative oedema, and later (in the second week of illness) membranous desquamation starting around the nail bed Cervical lymphadenopathy, often unilateral and large (≥1.5 cm) Kawasaki disease was first reported in Japan more than 40 years ago,w1 and the condition has since been described in most populations. It is not clear if Kawasaki disease is a new disease; reports of similar clinical features are rare in Japan before the mid-20th century, whereas in Europe infantile polyarteritis nodosa, a much rarer condition that shares many features with Kawasaki disease, has been described for more than a century.3