Abstract: Objective To analyze the respiratory pathogenic spectrum of nasopharyngeal secretions of influenza-like illness（ILI） cases with negative influenza virus nucleic acid in children under five years old in Baiyin City,provide the basis for the prevention and control of respiratory diseases in children. Methods The fluorescence quantitative multiplex PCR technology（TaqMan respiratory pathogenic microfluidic chip） was used to detect 38 respiratory pathogens,including human parainfluenza virus,respiratory syncytial virus,rhinovirus,enterovirus,chlamydia pneumoniae,mycoplasma pneumoniae,Haemophilus influenzae and Pneumocystis pneumoniae,in the nasopharyngeal secretion specimens from 409 ILI cases with negative influenza virus nucleic acid in children under five years old from November 2020 to May 2021,and the data were analyzed. Results Among 409 samples,no bacteria,mycoplasma,chlamydia and fungi covered by the TaqMan respiratory pathogenic microfluidic chip of this study were detected. The total detection rate of viruses was 60.64%（245/409）,including 13.45%（55/409） of parainfluenza virus,12.47%（51/409） of respiratory syncytial virus,9.29%（38/409） of rhinovirus,8.80%（36/409） of enterovirus,6.60%（27/409） of human metapneumovirus,5.62%（23/409） of adenovirus,2.20%（9/409） of coronavirus,and 2.20%（9/409） of bocavirus. The total virus infection rate of children was 50.61%,of which the single virus infection rate was 41.81%,the mixed virus infection rate was 8.80%,and the mixed infection rate of rhinovirus and enterovirus was the highest,which was 38.89%. Conclusion A variety of respiratory viruses are detected in the nasopharyngeal secretions of ILI cases with negative influenza virus nucleic acid in children under five years old in Baiyin City,the pathogenic spectrum is complex,the positive detection rate of respiratory virus infection in children of different age groups is different,some children have mixed infection of two or more viruses,so the differential diagnosis and monitoring of children's ILI should be strengthened to ensure the healthy growth of children.

Key words: Negativeinfluenza virus nucleic acid, Influenza like illness, Respiratory pathogen spectrum, Mixed infection