Human bocavirus and acute wheezing in children

Abstract

Background: Human bocavirus is a newly discovered parvovirus. It has been detected primarily in children with acute lower respiratory tract infection, but its occurrence, clinical profile, and role as a causative agent of respiratory tract disease are not clear.

Methods: We investigated the presence of human bocavirus by quantitative polymerase chain reaction of nasopharyngeal aspirate specimens and selected serum samples obtained from 259 children (median age, 1.6 years) who had been hospitalized for acute expiratory wheezing. The samples were analyzed for 16 respiratory viruses by polymerase chain reaction, virus culture, antigen detection, and serological assays.

Results: At least 1 potential etiologic agent was detected in 95% of children, and >1 agent was detected in 34% of children. Human bocavirus was detected in 49 children (19%). A large proportion of the cases were mixed infections with other viruses, but human bocavirus was the only virus detected in 12 children (5%). High viral loads of human bocavirus were noted mainly in the absence of other viral agents, suggesting a causative role for acute wheezing. In addition, infections that had uncertain clinical relevance and low viral loads were prevalent. Human bocavirus DNA was frequently detected in serum specimens obtained from patients with acute wheezing, suggesting systemic infection.

Conclusions: Human bocavirus is prevalent among children with acute wheezing and can cause systemic infection. Results suggest a model for bocavirus infection in which high viral loads are potentially associated with respiratory symptoms and low viral loads indicate asymptomatic shedding. Therefore, quantitative polymerase chain reaction analysis may be important for additional studies of human bocavirus.

Table 1

Viral etiology of respiratory infection in 259 children with acute wheezing during a 20-month study period.

Figure 1

Distribution of human bocavirus (HBoV) genome loads among all 49 nasopharyngeal aspirate samples that tested positive for HBoV. Each sample is represented by a single dot. The dotted line indicates the cutoff between the high and low HBoV load groups discussed in the text.

Table 2

Distribution of patients by the presence of human bocavirus (HBoV), the HBoV load in the nasopharynx, and the presence or absence of other viruses.

Table 3

Prevalence of patients with human bocavirus (HBoV) in the serum and median serum HBoV DNA level, in relation to the presence of HBoV in the nasopharynx, among patients with acute wheezing.

Table 4

Characteristics of children with acute wheezing caused solely by human bocavirus (HBoV), enterovirus, rhinovirus, or respiratory syncytial virus (RSV) or by bocavirus associated with other viruses.