Abstract / Summary
Abstract Background Acute respiratory infections pose a substantial global health burden, particularly among children. Influenza-like illness (ILI) is a common syndrome with complex and insufficiently characterized etiology, especially in central China. This study aimed to delineate the respiratory pathogen spectrum, age-specific dynamics, temporal succession, and co-infection patterns in pediatric ILI. Methods A total of 154 pediatric ILI outpatients were enrolled at Henan Children’s Hospital during the 2025–2026 epidemic season. Respiratory specimens were analyzed using a 132-target multiple nucleotide polymorphism marker method with next-generation sequencing. Pathogen detection rates, viral and bacterial loads, age-stratified distributions, temporal trends across three epidemic phases (early, peak, late), and inter-pathogen co-occurrence networks were evaluated. Hierarchical clustering identified distinct co-infection clusters. Results Overall pathogen detection rate was 72.1%, with mixed infections in 57.8% of cases. Neisseria meningitidis (Nm, 36.4%) and Haemophilus influenzae (Hi, 33.1%) were most prevalent. Hi increased with age (0% to 51.2%, p<0.001); human herpesvirus 5 predominated in infants <12 months and declined (p<0.001); Nm showed a U-shaped distribution (p=0.002). The epidemic season had a three-phase succession: bacteria-precede (Oct–Nov) led by Nm, virus-polarize (Dec–Jan) dominated by influenza A virus, and niche-replacement (Feb–Mar) with increased human parainfluenza virus 3 (p=0.003). Respiratory syncytial virus load peaked during the peak phase (p=0.027), and Nm load correlated negatively with age (r=−0.349, p=0.019). Network analysis identified Nm and Hi as central hubs, positively correlated with Streptococcus pneumoniae and each other, with strong intra-subtype correlation between influenza A subtypes. Hierarchical clustering revealed three co-infection patterns: virus-dominated, bacteria-dominated, and high-colonization background. Conclusions This study reveals a complex respiratory pathogen landscape in pediatric ILI, with high mixed infection rates and dynamic age- and time-dependent patterns. These findings underscore the importance of pathogen interactions and microecological contexts, providing insights for clinical diagnosis and public health strategies.