A Kawasaki Disease-Like Presentation in a Child with Concurrent Detection of Group A Streptococcus and Adenovirus: A Case Report on the Characterization of Physical Findings and Short-Interval Reassessment

Background and Clinical Significance: Kawasaki disease (KD) lacks specific diagnostic tests and requires early diagnosis and treatment to prevent coronary artery lesions. Concurrent infections may produce KD-like presentations; however, practical management of this time-sensitive uncertainty remains poorly described. Case Presentation: A previously healthy 4-year-old boy developed a rash after fever, rhinorrhea, cough, and a sore throat. On day 5, bilateral bulbar conjunctival injection, rash, palmar erythema, and fever met the four principal Japanese diagnostic criteria for KD. Purulent ocular discharge was accompanied by conjunctival injection, and the rash was scarlatiniform. Rapid antigen tests for group A Streptococcus (GAS) and adenovirus (AdV) were positive. Echocardiography revealed no coronary artery dilatation. The clinical presentation was considered most consistent with concurrent GAS and AdV infections, and amoxicillin was initiated. As incomplete KD remained possible, the patient was reassessed on day 7, 48 h later; all symptoms resolved. C-reactive protein was elevated (5.59 mg/dL), but none of the six supplemental laboratory criteria in the American Heart Association incomplete-KD algorithm were met. As the clinical support for KD decreased, observation was continued, with instructions to return if the principal features recurred. No KD-related symptoms occurred, and a telephone follow-up confirmed a favorable course. Conclusions: In children with multiple principal clinical features of KD and suspected co-infections, KD should not be excluded solely based on positive pathogen tests. Characterizing individual findings, including ocular discharge and rash morphology, and short-interval reassessment of the same findings within the therapeutic window for KD may help manage diagnostic uncertainty.