Study on the common viral etiologies of acute low respiratory tract infection among children in Children's Hospital of Fudan University,Shanghai

Objective To identify the viral etiologies of acute lower respiratory tract infection(ALRTI)in children living in Shanghai area by using a nested reverse transcription-polymerase chain reaction(nested RT-PCR)assay for the defection of specific gene fragments of human Rhinovirus(HRV)RNA and the direct immtmofluorescence assays(DFA)for the detection of other viruses.Methods A total of 342 nasopharyngeal secretion(NPS)samples were collected from ALRTI cases who were hospitalized during January 2005-December 2005.Nested RT-PCR techniques were used to detect HRV-specific RNA.Fifteen of the 46 positive PCR products were sequenced which were further compared with those in the GeneBunk.DFA was used to identify other viral etiologies,including respiratory syncytial virus(RSV),type A and type B influenza viruses(IFV),type 1,2 and 3 parainfluenza viruses(PIV)and adenovirus(ADV).Viral epidemiolngical data and seasonal variations were analyzed.The clinical characteristics of virus infections were also investigated.Results Among 342 cases included in this study,130 cases(38%)showed positive viral etiology.RSV positive cases accounted for 64(18.70%),and 46 of 64 RSV infections(71. 8%)was found in children less than 1 year old.RSV infections occured mainly from September of December.Forty-six(13.45%)samples were positive for HRV,and 38 of them(82.6%)were fotmd in less than 3 year old.HRV infections were most prevalent from March to May. The remaining viral etiologies included ADV(9 cases,2.63%),PIV(8 cases,2.3%),and IFV(7 cases,2.0%).Co-infections by 2viruses were found in 4 cases.When compared to the HRV sequences in the GeneBank,the 15 amplicons produced in this study showed overall high homology(83%～97%)although the sequences of 15 amplicons were highly varied.Among 130 NPA samples that showed positive virus infections,122 cases were diagnosed as pneumonia.These patients showed low grade fever.WBCs in most of these patients(71.5%)were less than 10×10~9/L,and majority patients' CRP(76.2%)were less than 8 mg/L,supporting the diagnosis of viral pneumonia.There were limited complications.All the people recovered with supportive treatment.Conclusion RSV and HRV were the two main viral etiologies for the low respiratory tract infections.HRV infections had more cases in children less than 3 year old.HRV infections occurred predominandy in the spring and autumn.Nested RT-PCR technique was highly specific,rapid and convenient for the detection of HRV RNA in ALRTI patients' NPS.The genome of HRV were the two main viral etiologies for the low respiratory tract infections.HRV infections had more cases in children less than 3 year old.HRV infections occurred predominantly in the spring and autumn.Nested RT-PCR technique was highly specific,rapid and convenient for the detection of HRV RNA in ALRTI patients' NPS.The genome of HRV was highly variable.