Analyses of Etiological characteristics of surveillance cases with acute respiratory infection in Hongkou District of Shanghai from 2022 to 2024

Objective To analyze the etiological characteristics of surveillance cases with acute respiratory infections in Hongkou District of Shanghai from 2022 to 2024, and to provide a basis for the prevention and control of respiratory infectious diseases as well as clinical diagnosis and treatment. Methods Respiratory samples were collected from 1 471 acute respiratory infection surveillance cases who visited 3 sentinel hospitals in Hongkou District from 2022 and 2024. Nucleic acid detection of 31 types of respiratory pathogens was performed using multiplex real-time fluorescence polymerase chain reaction (RT-PCR) technology, and the results were analyzed. Results The overall pathogen detection rate among the 1 471 cases was 39.97%, with viruses being the predominant pathogens and the highest detection rates for SARS-CoV-2 (13.94%, 205/1471), influenza virus (13.12%, 193/1471) and parainfluenza virus (2.52%, 37/1471). The detection rate rose markedly from 2022 onwards, with the number of pathogen types detected showing a year-on-year increase. The pathogen detection rate was the highest in winter (46.48%, 165/355). The detection rate was significantly higher in influenza-like illness cases (50.68%，387/764) than in severe acute respiratory infection cases (28.43%，201/707) (χ²=75.59，P<0.001). Higher detection rates in ILI cases were observed for SARS-CoV-2 (χ²=25.53, P<0.001), influenza virus (χ²=71.64, P<0.001), and adenovirus (χ²=7.65, P=0.006). In contrast, Klebsiella pneumoniae (χ²=10.08, P=0.002) and Mycoplasma pneumoniae (χ²=5.50, P=0.019) had higher detection rates among SARI cases. The minor age group had the highest detection rate (56.00%,28/50) among all age groups. A total of 43 cases of co-detection with two or more pathogens were identified, accounting for 7.31% of all positive cases. Among these cases, viral-bacterial co-detection accounted for the highest proportion (55.81%, 24/43), and most of them were co-detections with two pathogens. Conclusion Influenza virus and SARS-CoV-2 were the main epidemic pathogens for acute respiratory infection cases in Hongkou District from 2022 to 2024. Pathogen distribution varied across case types, seasons, and age groups. Continuous etiological monitoring and analyses for ARI cases should be carried out.