The human bocavirus role in acute respiratory tract infections of pediatric patients as defined by viral load quantification.

The major objective of this study was to investigate the pathogenic role of human bocavirus (hBoV) in patients hospitalized with acute respiratory tract infection (ARTI). Overall, 685 respiratory samples from 426 patients were examined by PCR for human bocavirus, as well as for other known human respiratory viruses. HBoV was quantified by PCR. Forty/283 (14.1%) pediatric patients, and 2/143 (1.4%) adult patients were found to harbor hBoV for a total of 45 episodes (16 detected as single infection, and 29 as coinfection) of hBoV-associated respiratory infection. HBoV DNA quantification revealed the presence of an NPA viral load > 1.0 x 10(5) DNA copies/ml in respiratory secretions from 17/40 (42.5%) children and 0/2 adults. Below this cut-off, hBoV appeared to be an innocent bystander or a persistent virus. Although hBoV may be frequently detected in children with upper or lower ARTI, in less than 50% young patients it appears to be potentially pathogenic.