| Objective Respiratory tract infections are a leading cause of mobidity and mortality in children worldwide.In June 2001,researchers in the Netherlands reported the discovery of a new respiratory virus,human metapneumovirus in the respiratory secretions of children with respiratory-tract disease. we sought to determine whether hMPV was circulating in Sochow area and to determine the epidemiology and clinical features associated with hMPV infection .in comparison with the associated RSV infection. To evaluate the therapeutic effects of recombinant interferon ( rIFN) and ribavirin treatment of acute bronchiolitis in infants caused by human metapneumovirus.Method Samples were collected from Novemember 2005,to October 2006,we tested respiratory specimens for the presence of hMPV by reverse-transcription polymerse chian reaction (RT-PCR).These specimens also assayed for respiratory syncytial virus,influenza virus A and B,parainfluenza viruses 1 to 3, and adenovirus by direct fluorescent antibody test . PCR products of hMPV N gene from some patients were randomly selected for sequencing analysis,and the sequences of the nucleotides and deduced amino acids were compared with those in the GeneBank. We applied randomized , controlled method to conduct the prospective clinical study in 51 infants with bronchiolitis caused by hMPV infection and compared the effects of rIFNα-1b and ribavirin on remission of acute phase symptoms , The rIFNα-1b group had 22 cases, ribavirin group had 15 cases and controlled group(conventional therapy) had 14cases.Results Of the 1932 patients screened, 6.6% had evidence of hMPV infection and was the second most common viral pathogen. Among them ,single hMPV infection were 123 cases, 5 of 128 hMPV-positive children (3.9%) had coinfection with other respiratory virus .The majority of hMPV-positive individuals were detected during the winter season . The median age age of patients was 22.17 months, and a majority (71.2 %) of children who tested positive for hMPV were aged <24 month. hMPV was identified in patients with either upper or lower respiratory tract infection or both . the infected children were diagnosed as having upper respiratory tract infection (1.6%), laryngitis (3.3%), bronchiolitis(41.5%), pneumonia (47.1%), and asthma exacerbation(6.5%). Clinical manifestions includeded fever, cough, rhinorrhea, wheezing and abnormal findings on chest radiographs (bronical thicking focal infiltrates , inflation,atelectasis). Clinical symptoms associated with hMPV infection were similar to those associated with RSV infection .but dyspnea,feeding difficulties and hypoxemia were more frequently in RSV infected children . Sequence analysis of these hMPV N genes showed 99%~100% homolgy to the registered sequence in GeneBank. Treatment with rIFNα-1b or ribavirin were superior to conventional treatment in terms of the number of days needed for elimination of symptoms and signs such as cough (P<0.01), wheezing ( P< 0.01) and rales (P<0.01) .Conculsion (1) hMPV accounted for a small but significant proportion of respiratory-tract disease in infants and children. (2) hMPV prevailed predominantly in the winter time .(3) hMPV infection was mainly associated with lower respiratory tract infections. (4) Clinically, hMPV infection can not be discriminated from the infection of other respiratory tract viruses. (5) coinfections of hMPV with other respiratory viruses were rare and clinically similar to single infections. (6) rIFNα-1b and ribavirin were demonstrated to be a safe and effective therapeutic approach to infants with bronchiolitis caused by hMPV.
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