# Impact of a Concurrent Respiratory Virus Infection on the Clinical Presentation and Response to Initial Treatment of Kawasaki Disease: A Single-Center Observational Study

## TL;DR

This study found that children with Kawasaki Disease who also had respiratory viruses showed different symptoms and better initial treatment responses.

## Contribution

The study is the first to show how concurrent respiratory viruses affect Kawasaki Disease symptoms and treatment outcomes in Japanese children.

## Key findings

- FARP-positive cases had higher Kobayashi scores and lower initial treatment failure rates.
- RSV-positive cases showed elevated liver enzymes and CRP levels compared to FARP-negative cases.
- RSV and RV/EV-positive cases responded better to initial treatment.

## Abstract

Background: The impact of respiratory viral infections associated with Kawasaki Disease (KD) cases on KD’s clinical presentation and initial response to treatment has not been clearly determined. Objective: This study aimed to evaluate respiratory viral infections using FilmArray Respiratory Panel (FARP) testing and analyze the effect of the concurrent presence of pathogens on clinical presentations of KD. Methods: Between January 2021 and June 2023, we conducted a retrospective, single-center observational study of 105 Japanese children with KD. KD was diagnosed and treated according to RAISE study guidelines, and the cases’ clinical information was assessed. FARP testing was performed in 71 out of 105 KD cases with fever and/or respiratory symptoms. Results: In 38 (53.5%) out of 71 cases, at least one virus was detected. The FARP-positive cases tended to have a higher frequency of Kobayashi scores (K-scores) ≥ 5 than the negative cases (42.1% vs. 21.2%), and lower initial treatment failure (7.89% vs. 21.2%). The most common virus detected was rhino/enterovirus (RV/EV: 27 cases), followed by seven cases of respiratory syncytial virus (RSV). RV/EV-positive KD cases did not differ significantly in their clinical data or the frequency of K-scores ≥ 5, and RSV-positive cases showed significantly elevated liver enzyme (AST:59 U/L (43.5–150.5) vs. 35 U/L (27–41), ALT:40 U/L (28.5–244.5) vs. 18 U/L (14–27)) and CRP levels (12 mg/dL (7.3–14.2) vs. 6.5 mg/dL (4.1–8.5)), and an increased frequency of K-scores ≥ 5 (71.4% vs. 21.2%) compared to FARP-negative cases. KD cases that were also RSV-positive or RV/EV-positive showed favorable responses to initial treatments. Conclusions: Concurrent respiratory virus infection could affect the clinical manifestation and initial treatment response of KD.