Trial of Pulse Steroid Therapy in Kawasaki Disease--Pediatric Heart Network

* Fever persisting at least 4 days and the presence of at least 4 of the following 5 principal features: 1. Changes in extremities: Acute changes include erythema and edema of hands and feet; Convalescent changes include membranous desquamation of fingertips 2. Polymorphous exanthema 3. Bilateral, painless bulbar conjunctival injection without exudates 4. Changes in lips and oral cavity: Erythema and cracking of lips, strawberry tongue, diffuse injection of oral and pharyngeal mucosae 5. Cervical lymphadenopathy ( 1.5 cm in diameter), usually unilateral; OR * Patients with at least four days of fever and coronary artery disease, defined as either: 1\. Having a z-score in either the proximal right coronary artery or the proximal left anterior descending coronary artery of \> 2.5 detected by 2-dimensional echocardiography, as well as: * For patients under six months of age, at least two principal criteria * For patients at least six months of age, at least three principal criteria. 2. Meeting Japanese Ministry of Health criteria for coronary aneurysm defined as an internal lumen diameter of \>3 mm in children less than 5 years of age or \>4 mm in children 5 years of age and older, in either the proximal right coronary artery or the proximal left anterior descending coronary artery and at least one principal criterion. AND Enrollment within ten days of the onset of illness, with Day 1 defined as the first day of fever AND Informed consent of parents and assent of children who are older than age 7 years and capable of understanding or according to institutional guidelines.