The Burden of Human Bocavirus 1 in Hospitalized Children With Respiratory Tract Infections

Background: Human Bocavirus 1 (HBoV1) is a small DNA virus that was first identified in children with respiratory tract infections (RTI). It has since been frequently detected with other respiratory viruses, and in children without RTI, making the burden of true HBoV1 RTIs challenging to assess. This study aimed to assess HBoV1 prevalence, codetections, seasonality, and hospitalization rates, and compare them to respiratory syncytial virus (RSV) using HBoV1-mRNA PCR as a marker for an active, replicating virus. Methods: During an 11-year period, 4,879 children who were admitted to the hospital with RTIs were enrolled in the study. Nasopharyngeal aspirates (NPAs) were collected from all children and tested for HBoV1, RSV, and 19 other respiratory pathogens. Results: HBoV1-DNA was detected in 6.2% of NPAs, making it the eighth most detected virus. Of the HBoV1-DNA positive samples, 47% were positive for HBoV1-mRNA. HBoV1-mRNA detection was more likely in the case of high viral load (>106 copies/ml), single detection (OR 3.9, 95% CI 1.7-8.9), and less likely in samples with codetections of severe viruses (RSV, human metapneumovirus, parainfluenza virus 1-3, influenza virus A/B) (OR 0.34, 95% CI 0.19-0.61). HBoV1-mRNA had a modest seasonal variation, peaking in autumn and winter. Children with a positive HBoV1-mRNA test were more likely to acquire a lower RTI diagnosis than those with a negative test. The mean yearly rate of hospitalizations >24 hours with lower RTI and HBoV1-mRNA was 0.70 per 1000 children