Frequency and Etiological Agents of Acute Gastroenteritis in Children: A Retrospective Analysis Before and During the COVID-19 Pandemic

Background Acute gastroenteritis (AGE) remains one of the leading causes of morbidity in children worldwide, with viral pathogens constituting the predominant etiological agents. The implementation of non-pharmaceutical interventions (NPIs) during the coronavirus disease 2019 (COVID-19) pandemic substantially altered the transmission dynamics of infectious diseases, including enteric pathogens. Objective To evaluate the frequency and etiological distribution of pathogens causing pediatric AGE and to assess temporal changes before, during, and after the COVID-19 pandemic. Methods In this retrospective single-center study, 5,966 pediatric patients presenting with suspected AGE between June 2015 and June 2023 were included. Stool samples were analyzed for viral, bacterial, and parasitic pathogens using rapid antigen tests, toxin assays, and conventional culture methods. Patients were categorized into three periods: pre-pandemic (June 2015–November 2019), pandemic (December 2019–June 2021), and post-pandemic (July 2021–June 2023). Statistical analyses were performed using appropriate tests according to variable distribution. Categorical variables were compared using the Pearson chi-square test, whereas continuous variables were analyzed using one-way ANOVA or the Kruskal–Wallis test, as appropriate. A two-sided p-value < 0.05 was considered statistically significant. Results An etiological agent was identified in 2,214 of 5,966 patients (37.1%). Age and sex distributions were comparable across study periods (p > 0.05). Overall pathogen positivity decreased significantly over time, from 40.4% in the pre-pandemic period to 36.3% during the pandemic and 30.3% during the post-pandemic period (p < 0.001). Viral pathogens predominated throughout all study periods. Norovirus was the most frequently detected pathogen, identified in 1,252 patients (21.0%), followed by rotavirus in 471 patients (7.9%) and adenovirus in 271 patients (4.5%). Among bacterial pathogens, Salmonella spp. was detected in 198 patients (3.3%), whereas parasitic and toxin-related pathogens were infrequently identified. Significant temporal changes in pathogen distribution were observed. Norovirus detection decreased significantly over time, whereas rotavirus detection increased significantly during the post-pandemic period (p < 0.001). Viral pathogens remained the dominant etiological agents throughout the study period despite an overall reduction in pathogen positivity. Conclusions Viral pathogens remain the leading cause of pediatric AGE. The implementation of NPIs during the COVID-19 pandemic was associated with a significant reduction in overall pathogen positivity and a shift in etiological distribution. These findings highlight the impact of public health measures on the epidemiology of pediatric AGE and underscore the importance of continuous surveillance to inform prevention strategies.