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

Abstract

Background: Human bocavirus 1 (HBoV1) is frequently codetected with other viruses, and detected in asymptomatic children. Thus, the burden of HBoV1 respiratory tract infections (RTI) has been unknown. Using HBoV1-mRNA to indicate true HBoV1 RTI, we assessed the burden of HBoV1 in hospitalized children and the impact of viral codetections, compared with respiratory syncytial virus (RSV).

Methods: Over 11 years, we enrolled 4879 children <16 years old admitted with RTI. Nasopharyngeal aspirates were analyzed with polymerase chain reaction for HBoV1-DNA, HBoV1-mRNA, and 19 other pathogens.

Results: HBoV1-mRNA was detected in 2.7% (130/4850) samples, modestly peaking in autumn and winter. Forty-three percent with HBoV1 mRNA were 12-17 months old, and only 5% were <6 months old. A total of 73.8% had viral codetections. It was more likely to detect HBoV1-mRNA if HBoV1-DNA was detected alone (odds ratio [OR]: 3.9, 95% confidence interval [CI]: 1.7-8.9) or with 1 viral codetection (OR: 1.9, 95% CI: 1.1-3.3), compared to ≥2 codetections. Codetection of severe viruses like RSV had lower odds for HBoV1-mRNA (OR: 0.34, 95% CI: 0.19-0.61). The yearly lower RTI hospitalization rate per 1000 children <5 years was 0.7 for HBoV1-mRNA and 8.7 for RSV.

Conclusions: True HBoV1 RTI is most likely when HBoV1-DNA is detected alone, or with 1 codetected virus. Hospitalization due to HBoV1 LRTI is 10-12 times less common than RSV.

Keywords: children; hospitalization rates; human bocavirus; respiratory tract infections; seasonality.

Figure 1.

Monthly number of virus detections in children hospitalized with respiratory tract infection at St. Olavs hospital from November 2006 to October 2017. (A) HBoV1-DNA (light orange color) and HBoV1-mRNA detections (dark orange color). (B) RSV detections (yellow color). The gray area represents the total number of NPA samples. HBoV1, human bocavirus 1; NPA, nasopharyngeal aspirate; RSV, respiratory syncytial virus

Figure 2:

Viral codetections with (A) human bocavirus 1 (HBoV1)-positive nasopharyngeal aspirates (NPAs) and (B) respiratory syncytial virus (RSV)-positive NPAs. Absolute number of codetections with other viruses are listed in the bars. Light orange bar corresponds to HBoV1-DNA-positive samples that are mRNA-negative or not tested for mRNA, and dark orange bar corresponding to HBoV1-positive samples that are mRNA-positive. Combined light and dark orange bars correspond to the total number of HBoV1-DNA-positive samples. The length of the bar corresponds to codetection frequencies in the percentage of all HBoV1 and RSV-positive NPAs, or all HBoV1 or RSV-positive NPAs tested for the relevant virus (missing data in codetections with HBoV1: 26 missing in PeV bar, 64 missing in HCoV bar and 20 missing in PIV4 bar. Missing data in codetections with RSV: 1 missing in HMPV bar, 1 missing in PIV1–3 bar, 49 missing in PeV bar, 270 missing in HCoV bar and 13 missing in PIV4 bar). HMPV, human metapneumovirus; PIV1–3, parainfluenza virus types 1–3; FLU A/B, Influenza virus A and B; RV, rhinovirus; HEV, human enterovirus; PeV, human parechovirus; HCoV, human coronavirus; HAdV, human adenovirus; PIV4, parainfluenza virus type 4.