Respiratory pathogen survey reveals mixed infections in Zhuhai children

A two-year surveillance study in Zhuhai, China, found respiratory pathogens in 64.56% of 2,788 patients, with nearly half of the positive samples containing more than one organism. The analysis, which examined people enrolled through influenza-like illness and severe acute respiratory infection surveillance, identified 20 of 22 pathogens tested. Children aged 0–14 years accounted for 96.11% of positive cases, making them the principal population affected in the study population.

Researchers analyzed throat-swab specimens collected from national sentinel influenza-like illness cases and hospitalized severe acute respiratory infection cases between January 2024 and December 2025. Each specimen was tested for 22 respiratory pathogens using real-time polymerase chain reaction, or real-time PCR. The study used descriptive epidemiology to characterize pathogen positivity, detect mixed infections and assess differences by age, sex and month. Because the sampling frame consisted of sentinel influenza-like illness cases and hospitalized patients with severe acute respiratory infection, the results describe the enrolled clinical populations rather than the full population of Zhuhai.

The most prevalent pathogens were Streptococcus pneumoniae, Haemophilus influenzae, human rhinovirus, influenza A virus, human adenovirus and Mycoplasma pneumoniae. Mixed infections were common: 48.28% of positive samples contained multiple pathogens, and the combination of S. pneumoniae and H. influenzae was the most frequent. These findings indicate substantial co-circulation during the study period, although the observational design does not establish whether any pathogen caused a particular illness or clinical outcome.

Pathogen detection also varied by sex. Positivity rates for human rhinovirus, S. pneumoniae and H. influenzae were significantly higher among males than females, whereas M. pneumoniae positivity was higher among females. The age distribution was strongly concentrated among younger patients. Children from birth through 14 years represented 96.11% of all positive cases, and the highest positivity rate was observed in the 4–14-year age group. This concentration reflects the populations included in the surveillance system and should not be interpreted as a population-wide estimate of disease incidence.

Monthly surveillance showed distinct seasonal patterns. S. pneumoniae and H. influenzae remained persistently dominant and produced synchronized peaks. Influenza A virus activity was marked by several epidemic peaks during the two-year period, while human rhinovirus circulated sporadically. M. pneumoniae and human adenovirus both peaked from May through September 2024. Overall, the results show that several respiratory pathogens circulated concurrently in Zhuhai from 2024 to 2025, with mixed infections, age disparities and pathogen-specific seasonal patterns. The authors concluded that children younger than 15 years were the primary affected group in the sampled population, supporting focused surveillance of this age group.

Subject of Research: Epidemiology of 22 respiratory pathogens among influenza-like illness and hospitalized severe respiratory infection cases in Zhuhai during 2024–2025

Article Title: Analysis of the pathogenic spectrum and epidemiological characteristics of 22 respiratory pathogens in Zhuhai City, China, 2024–2025

Article References: Yang, W., Huang, H., Guo, Z., Liu, J., Cui, Y., Li, H., & Huang, W. (2026). Analysis of the pathogenic spectrum and epidemiological characteristics of 22 respiratory pathogens in Zhuhai City, China, 2024–2025. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14054-3

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14054-3

Keywords: respiratory viruses, respiratory bacteria, mixed infections, real-time PCR, epidemiological surveillance, Zhuhai, influenza-like illness, severe acute respiratory infection, children, seasonality, Analysis, pathogenic