Human bocavirus in children with acute respiratory infections in Vietnam

Acute respiratory infections are the major cause of morbidity and mortality globally. Human bocavirus (HBoV), a novel virus, is recognized to increasingly associate with previously unknown etiology respiratory infections in young children. In this study, the epidemiological, clinical, and molecular characteristics of HBoV infections were described in hospitalized Vietnamese pediatric patients. From April 2010 to May 2011, 1,082 nasopharyngeal swab samples were obtained from patients with acute respiratory infections at the Children's Hospital 2, Ho Chi Minh City, Vietnam. Samples were screened for HBoV by PCR and further molecularly characterized by sequencing. HBoV was found in 78 (7.2%) children. Co-infection with other viruses was observed in 66.7% of patients infected with HBoV. Children 12-24 months old were the most affected age group. Infections with HBoV were found year-round, though most cases occurred in the dry season (December-April). HBoV was possible to cause severe diseases as determined by higher rates of hypoxia, pneumonia, and longer hospitalization duration in patients with HBoV infection than in those without (P-value <0.05). Co-infection with HBoV did not affect the disease severity. The phylogenetic analysis of partial VP1 gene showed minor variations and all HBoV sequences belonged to species 1 (HBoV1). In conclusion, HBoV1 was circulating in Vietnam and detected frequently in young children during dry season. Acute respiratory infections caused by HBoV1 were severe enough for hospitalization, which implied that HBoV1 may have an important role in acute respiratory infections among children.