Incomplete KD should not be equated with mild KD. Patients with four principal symptoms were comparable to cKD with respect to CAA occurrence. In patients with one to three symptoms also, especially in those under 1 year and older than 4 years of age, other significant symptoms and laboratory findings of the guidelines are very important in making a correct and early diagnosis of iKD so as to prevent CAA.

Although human coronavirus (HCoV)-NL63 was once considered a possible causative agent of Kawasaki disease based on RT-PCR analyses, subsequent studies could not confirm the result. In this study, this possibility was explored using serological tests. To evaluate the role of HCoV infection in patients with Kawasaki disease, immunofluorescence assays and virus neutralizing tests were performed. Paired serum samples were obtained from patients with Kawasaki disease who had not been treated with γ-globulin. HCoV-NL63 and two antigenically different isolates of HCoV-229E (ATCC-VR740 and a new isolate, Sendai-H) were examined as controls. Immunofluorescence assays detected no difference in HCoV-NL63 antibody positivity between the patients with Kawasaki disease and controls, whereas the rate of HCoV-229E antibody positivity was higher in the patients with Kawasaki disease than that in controls. The neutralizing tests revealed no difference in seropositivity between the acute and recovery phases of patients with Kawasaki disease for the two HCoV-229Es. However, the Kawasaki disease specimens obtained from patients in recovery phase displayed significantly higher positivity for Sendai-H, but not for ATCC-VR740, as compared to the controls. The serological test supported no involvement of HCoV-NL63 but suggested the possible involvement of HCoV-229E in the development of Kawasaki disease.

Nationwide epidemiological surveys of Kawasaki disease have been conducted nine times in Japan since 1970. By the end of 1986, 83,857 (male:female ratio, 1.4) cases were reported. We summarize the results of these surveys, especially the latest survey of cases from January 1985 to December 1986. There were three epidemic years - 1979, 1982, and 1986. The ratios of the number of patients diagnosed in each of those years to the number in the preceding year were 2.0, 2.4, and 1.7, respectively. The last epidemic started in a metropolitan area of Tokyo in December 1985 and propagated northwards and southwards to involve almost all of the country in six months. The age-specific incidence curve showed a unimodal peak at nine to 11 months of age. The proportion of sibling cases was approximately 2%. The epidemiological pictures suggested that the disease was caused by an unknown biologic agent that is common in the community and that spreads easily among very young children.

Kawasaki disease (KD) is an acute multisystem vasculitis of unknown etiology and is associated with marked activation of T cells and monocyte macrophages, leading to the assumption that superantigens are involved in its pathogenesis. To determine if an association exists between streptococcal superantigens and KD, we examined serum antibody responses to superantigens in sera from 50 paired acute and convalescent KD patients using purified recombinant streptococcal superantigens, such as SPEA, SPEC, SSA and MF. We found a very low frequency of detection of anti-superantigen antibodies by ELISA and no marked IgG seroconversion to each superantigen, indicating the absence of a serological relationship between toxin-producing streptococcal infection and the onset of KD.