Association of Human bocavirus with Respiratory Infections in Outpatients and in Patients Attended at a Reference Hospital.

The role of Human bocavirus (HBoV) in human infectious disease is unclear due to the frequent detection of this virus in association with other respiratory viruses with a recognized pathogenic role in acute respiratory infection. We have analyzed the impact of HBoV in outpatients and in patients requiring hospitalisation or emergency attention for acute respiratory infections. Respiratory viruses were investigated by real-time PCR, direct antigen detection and/or viral culture by shell-vial assay. Nasopharyngeal aspirates, BAL and/or sputum samples from patients attended at a reference hospital, and nasal/throat swabs from outpatients were used. Respiratory viruses were detected in 660 samples (47%). HBoV detection rate was 12.6%, only preceded by respiratory syncytial virus (25%). Co-detections were observed in 12.9% of samples, and HBoV was present in 81% of them. Similar detection rates of HBoV were obtained in individuals with positive and negative results for other respiratory viruses (12.5% and 12.7%, respectively). The crossing point value was taken as a measure of HBoV viral load. Higher HBoV loads were observed in children, and in patients from the hospital. HBoV viral load was not associated with symptoms of upper respiratory tract infection or lower respiratory tract disease. Although HBoV is frequently detected in respiratory specimens, there is a poor association between HBoV-positive specimens and clinical parameters. A clinical impact of HBoV in respiratory infection probably occurs in few cases.