Clinical analysis of influenza virus-associated acute lower respiratory tract infection in children in Beijing during 2007-2014

Abstract

Objective To investigate the status of influenza virus (IFV) in children with acute lower respiratory tract infection (ALRTI) in Beijing, and to compare the clinical characteristics of ALRTI with single IFV and respiratory syncytial virus(RSV) in children. Methods Throat swab of nasopharyngeal aspirate specimens were collec-ted from children with ALRTI and tested for the presence of respiratory viruses (such as RSV, parainfluenza virus, rhinovirus and IFV) by reverse transcription-polymerase chain reaction.The epidemiological features of patients with influenza A, B or C virus (IFA, IFB, IFC) infection were analyzed.Clinical features of patients with single IFV and single RSV infection were compared. Results (1) During March 2007 and March 2014, at least one virus was detected in 2 697 (67.2%)of 4 012 children.There were 256 samples positive for IFV (6.4%), including 154 samples for IFA (3.8%), 97 samples for IFB (2.4%), and 6 samples for IFC (0.1%). (2) The IFV positive rate of 6 years groups were 4.1%, 7.6%, 12.0%, 7.8% and 4.8%, respectively.The 1-3 years-old group showed the highest positive rate of IFV.The positive rate of IFV showed no difference between males and females(6.7% vs 5.9%, χ2=2.63, P>0.05) (3) There were 16, 15 and 175 hospitalized children in single IFV, single IFB and single RSV infection group, respectively.The rate of <1-year children in single IFA(43.8% vs 84.0%, χ2 =12.74, P<0.001 or IFB (33.3% vs 84.0%, χ2 =19.11, P<0.001)infection group were both higher than it in single RSV infection group, and there was a significant difference.The incident rate of severe pneumonia in single IFA or IFB infection groups were both higher than that in single RSV infection group significant difference (31.2%, 26.7% vs 4.0%; χ2=18.49, 13.01, all P<0.001). The incident rate of trachea cannula in single IFA and IFB infection groups were higher than in single RSV infection group, and the difference was significant(25.0%, 13.3% vs 1.7%; χ2=22.51, 7.28, P<0.001, P=0.001). There was no significant difference in other clinical features, diagnosis and mechanical ventilation between single IFA infection group and single RSV infection group or single IFB infection group and single RSV infection group. Conclusions IFV is one of the major viral pathogens in children in Beijing.Peaks of influenza infection activity in children were in spring and winter.Children, especially 1-6 years old group, were more susceptible to IFV.The ALRTI children infected with IFV or RSV showed the similar clinical characteristics and severity of disease, but the incident rate of severe pneumonia was higher in children infection with IFV. Key words: Acute lower respiratory tract infection; Influenza virus; Respiratory syncytial virus; Clinical cha-racteristics; Child