Multi-dimensional epidemiology of pediatric acute respiratory tract infection in Ningbo, China (2020–2024): age-specific susceptibility, pathogen dynamics, and epidemiological trends

Background Pediatric acute respiratory tract infection (ARTI) constitutes a major global health threat. Since 2020, global containment measures have disrupted pathogen circulation patterns, leading to altered epidemiological profiles across multiple pathogens with marked regional heterogeneity. Current research in Ningbo predominantly focuses on single-pathogen surveillance or short-term monitoring, lacking systematic analysis of multi-pathogen interactive dynamics, age-specific susceptibility mechanisms, and co-infections. Methods Clinical data from all 191,967 pediatric patients with ARTI at Ningbo LiHuili Hospital (2020–2024) were collected. Laboratory testing including influenza A/B virus (IFV-A/B) detection, Mycoplasma pneumoniae (MP) testing, 13 respiratory pathogens analysis, and bacterial culture was systematically integrated and analyzed. Results From 2020 and 2024, the number of ARTI cases initially increased and then decreased, peaking in 2023. The incidence was highest in autumn and lowest in summer. Among all cases, 75,001 (39.07%) were diagnosed with acute lower respiratory infection (ALRI), with children aged 6 years exhibiting the highest susceptibility. Of the 41,766 cases tested, the overall pathogen detection rate was 67.61%. IFV-A/B, Human Parainfluenza Virus (HPIV), and Human Adenovirus (HAdV) were more frequently detected in acute upper respiratory tract infections (AURI) ( P < 0.05), while Human Rhinovirus (HRV), Respiratory Syncytial Virus (RSV), and MP were predominantly identified in ALRI cases ( P < 0.05). Each pathogen exhibited age-specific susceptibility patterns. Several pathogens, such as IFV-A, MP, and HAdV, displayed distinctive epidemic peaks. Co-infections were common, with a 17.38% co-infection rate observed in the group tested for 13 respiratory pathogens, and a higher co-infection rate of 39.49% when testing combined respiratory pathogens and bacteria. Correlation analysis among pathogens revealed predominant antagonistic interactions between viruses, positive associations among bacteria, and generally positive interactions between viruses and bacteria, though overall correlation strengths were weak. Conclusion Pediatric ARTI exhibit age-specific susceptibility and pathogen variation. The 2023–2024 resurgence demands precision control strategies for optimized intervention.