Izumi fever (IF), also known as Far East scarlet-like fever (FESLF), is caused by Yersinia pseudotuberculosis and it has clinical features resembling those of Kawasaki disease (KD). As both diseases are rare in adolescents and young adults, it is challenging to recognize them, thus often leading to a delayed diagnosis. We herein present two cases of IF or FESLF (IF/FESLF). The first case was misdiagnosed as KD, which led to a diagnostic delay. The second case was recognized earlier owing to our experience with the first case. Although cultures were negative in both cases, presumably due to the prior use of antimicrobial agents, our clinical suspicion and a paired serological assay for anti-Y. pseudotuberculosis antibodies finally led to a successful diagnosis.
Keywords: Far East scarlet-like fever; Izumi fever; Kawasaki disease; Yersinia pseudotuberculosis; superantigen.