Human Bocavirus 1 Primary Infection and Shedding in Infants

Abstract

Background: Human bocavirus 1 (HBoV-1) is frequently detected in young children. The role of HBoV-1 in respiratory illness is unclear, owing to frequent detection in asymptomatic children.

Methods: Weekly oral fluid samples from a longitudinal cohort of infants were tested by quantitative polymerase chain reaction for HBoV-1 DNA. Symptoms during HBoV-1 primary shedding events were compared to those during 14-day control periods occurring 1 month prior to and following the primary event. Eight single-nucleotide polymorphisms were analyzed to assess HBoV-1 variants.

Results: Sixty-six of 87 children (76%), followed for at least 18 months from birth, had a primary HBoV-1 infection. HBoV-1 was consistently detected for >1 month (maximum duration, 402 days) following 42 of 66 primary shedding events. Children were more likely to experience new cough symptoms (odds ratio [OR], 2.7; 95% confidence interval [CI], 1.4-5.5) and to visit a healthcare provider (OR, 2.8; 95% CI, 1.02-7.7) during the 14 days surrounding the time of initial detection of HBoV-1. Recurrent HBoV-1 shedding events were found in 33 children (50%). Twelve of 48 children with HBoV-1 variant data had multiple viral allelic patterns over time.

Conclusions: HBoV-1 primary shedding events are associated with mild respiratory illness with subsequent prolonged detection of HBoV-1 DNA for up to a year. HBoV-1 reinfection contributes to long-term shedding.

Keywords: bocavirus; infant; oral fluid; respiratory tract; single nucleotide polymorphism.

Figure 1.

Symptom timing around the human bocavirus 1 (HBoV-1) primary event. Height of gray bars indicates number of children with a healthcare visit, fever, or new-onset cough (y-axis) on a given day (x-axis) relative to the beginning of the HBoV-1 primary event. The continuous line was generated using a median cubic spline (Stata 11) and represents a smoothed curve of the daily symptom prevalence. The area between the black reference lines represents the predefined primary event period.

Figure 2.

Human bocavirus 1 (HBoV-1) alleles over time in 12 children. The first, second, and third allele patterns in each individual child are represented by changes in shape and color. Gray circles indicate tested samples with no HBoV-1 detected.