OBJECTIVEThe impact of human bocavirus (HBoV), a newly identified human parvovirus, on childhood persistent wheezing has not been identified. In this study, the clinical features of infantile persistent wheezing induced by HBoV was analyzed.

METHODSTracheal aspirates were collected by bronchofibroscope or nasopharyngeal (NP) aspirates from April, 2006 to January, 2007. HBoV DNA in the tracheal aspirates of 33 children with persistent wheezing and in NP aspirates of 6 children with persistent wheezing, who had at least or more than four weeks wheezing. RSV was identified by virus isolation in Hep-2 cells and antigen detetion by direct immunofluorescence assay (DIFA) which was also used for diagnosis of adenovirus, influenza A and B, parainfluenza 1, 2, 3 infection.

RESULTSOf the 39 children with persistent wheezing, 12 cases (31%) were positive for HBoV DNA. Age of HBoV-positive patients ranged from 2 month to 1 year. The results of sequencing of PCR products proved that sequences of HBoV DNA from these 12 samples were exactly identical to the those of HBoV stored in GeneBank (accession numbers DQ000495 and DQ000496). Two cases with HBoV infection were found to be co-infected with RSV. Ten of the 12 HBoV-positive samples were collected during the period from winter to spring (1 in November, 4 in December, 2 in January and 3 in April), the other two HBoV-positive samples were collected during the period from summer to autumn (1 in May and the other in July). Seven of the 12 HBoV DNA-positive patients had fever, 5 of them had high fever. Significantly more patients with HBoV infection had fever as compared to patients with RSV infection. All the HBoV positive patients showed abnormal findings on chest X ray such as interstitial infiltrates, lung infiltration and hyperinflation. Abnormal findings on chest X ray were found in higher proportion of HBoV positive patients as compared with RSV positive patients. And other manifestations such as wheezing, cough and respiratory distress had no significant difference between HBoV and RSV infected patients.

CONCLUSIONSThis study further demonstrated that HBoV probably is a common pathogen of lower respiratory infection in children and might particularly be associated with persistent wheezing.