Abstract:

Objective　To study the correlation of human bocavirus (HBoV) viral load and disease severity in children with lower respiratory tract infections. Methods 　Nasopharyngeal aspirates(NPAs) from 554 in-hospital children with lower respiratory tract infections under 5-year-old and swabs from 195 healthy children were collected from January 2009 to September 2012. The types of HBoV and HBoV viral load were determined by fluorescence polymerase chain reaction (PCR). The other respiratory viruses were determined by commercial kits.The results were analyzed with clinical symptoms and biochemistry parameters. Results　The positive rates of HBoV between in-hospital children and healthy children had obvious difference.The HBoV viral loads of in-hospital children (5.10×10⁶ copies/mL) were significantly higher than those of healthy children (2.70×10³ copies/mL, P<0.05). Among co-infection in-hospital children, the HBoV viral loads of mild and moderate groups (2.70×10⁵ and 3.85×10⁶ copies/mL) were lower than that in severe group (8.70×10⁶ copies/mL, P<0.05). There was 1 case ofnewborn infant with severe pneumonia, and HBoV were found in NPAs, blood and stool samples without other common respiratory trract virus and bacterium infections. Conclusions　HBoV is a pathogen for respiratory tract disease in children. HBoV viral load is correlated positively with disease severity in co-infection patients. HBoV can cause severe pneumonia in some children.

Key words: Human bocavirus, Viral load, Severe pneumonia, Child