The purpose of this study is to investigate the infectious etiology of Kawasaki disease (KD); a prospective household and case control study for Kawasaki disease will be done. The investigators will enroll Kawasaki disease cases who have at least five of the following manifestations:

1. fever for over 5 days
2. neck lymphadenopathy
3. lip fissure and/or strawberry tongue
4. skin rash
5. nonpurulent bulbar conjunctivitis
6. palm/sole erythema and induration followed by desquamation, or coronary artery aneurysm with less than 5 of the above manifestations (atypical Kawasaki disease)

The KD cases will receive virological (virus isolation from the blood, throat swabs and rectal swabs or stool, gene chip for possible viruses from stored RNA and DNA), bacterial (blood, throat swabs and stool: bacterial culture and stored strain for further toxin or superantigen detection), and serological (Mycoplasma pneumoniae, Chlamydiae pneumoniae, ASLO, HHV6, EV71, peptide library approach for auto-antibody or pathogen-related antibody, stored serum for further workup) workup. Stored DNA from the blood will also be performed.