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Human Bocavirus Infection in Children
Abstract & Commentary
By Hal B. Jenson, MD, Chief Academic Officer, Baystate Health Professor of Pediatrics and Dean of the Western Campus of Tufts University School of Medicine, is Associate Editor for Infectious Disease Alert.
Dr. Jenson is on the speaker's bureau for Merck.
Synopsis: Human bocavirus was detected by quantitative polymerase chain reaction in 19% of asopharyngeal aspirate specimens from 259 wheezing children, usually as a mixed infection with other viruses. An association with acute wheezing in children is suggested.
Source: Allander T, et al. Human bocavirus and acute wheezing in children. Clin Infect Dis. 2007;44:904-910.
The possible presence of 16 different respiratory viruses, including human bocavirus, was tested by quantitative polymerase chain reaction (PCR) (16 viruses), virus culture (9 viruses), and antigen detection (7 viruses) of nasopharyngeal aspirates and also acute- and convalescent-phase serologies (7 viruses) from 259 children (range, 3 months to 15 years; median age, 1.6 years) hospitalized for acute wheezing. In addition, human bocavirus was investigated in 64 hospitalized children (rage 5 months to 14 years; median age 4.1 years) who were asymptomatic for wheezing.
At least one viral agent was detected in 95% of children, with >1 agent detected in 34% of children. Pathogens were identified by PCR in 95% of children, virus culture in 40%, antigen detection in 28%, and serologies in 28%. Diagnosis was based on serologies in only 3% of children. Rhinoviruses (73 children, 28%), respiratory syncytial virus (RSV) (72 children, 28%), enteroviruses (69 children, 27%), nontypable rhinoviruses/ enteroviruses (31 children, 12%) and human bocavirus (49 children, 19%) were the most common agents identified. Pathogens were identified in 95% of children, with one virus in 60% and ≥ 2 viruses in 34%. Human bocavirus was detected in 49 children (19%), usually as part of a mixed infection with another agent, most commonly rhinoviruses (14 children), enteroviruses (8 children), and RSV (7 children).
An association with acute wheezing in children was suggested by finding human bocavirus more frequently among children with acute wheezing than among asymptomatic children (19% vs 0%; P < 0.001), the highest bocavirus loads primarily in the absence of other viral agents, and higher detection of human bocavirus DNA in acute serum samples, indicating systemic infection.
Human bocavirus was first described in 2005 after large-scale molecular screening of respiratory specimens for viral genome sequences. It is one of several recently described viruses-including human metapneumovirus and coronaviruses (SARS)-that were initially detected by screening nasopharyngeal aspirates by PCR for new viral sequences. Human bocavirus is a novel parvovirus that is related to minute virus of canine and bovine parvovirus. There are now a handful of studies that show that shedding of human bocavirus, either continuous or in association with other viral respiratory pathogens, appears to be common in children.
These results show that a viral agent is able to be identified in most children with acute wheezing, and also evidence of an association of human bocavirus with acute wheezing in children. These epidemiologic studies do not confirm a causal role for human bocavirus. The high frequency of multiple infections with 2 or even 3 viruses suggests that childhood wheezing is a common result of single or perhaps the interaction of multiple viral respiratory pathogens. Our current understanding of the role of human bocavirus in causing human disease is limited by the limits of the specimen collections that have facilitated use of microarrays, consensus PCR assays, and high-throughput sequencing to identify these viruses. Confirmation of the pathogenic role of human bocavirus awaits testing of specimen sets that includes the necessary controls.