Human bocavirus: developing evidence for pathogenicity.

In this issue of the Journal of Infectious Diseases, 2 articles by Kesebir and colleagues at Yale–New Haven Hospital and Yale University School of Medicine (New Haven, Connecticut) [1] and by Manning and colleagues at the Royal Infi mary of Edinburgh (Edinburgh, United Kingdom) [2] describe the detection, primarily in hospitalized infants, of human bocavirus (HBoV) in respiratory tract samples obtained during acute lower respiratory tract illness. The human bocavirus, which was firs described in September 2005, was discovered by random polymerase chain reaction (PCR) amplificatio of pooled respiratory samples obtained from children hospitalized in Sweden [3]. The amplicons were sequenced, and several viruses were found, including the human bocavirus, with subsequent identificatio of sensitive and specifi primer sequences. The virus has now been found by at least 9 groups of investigators in Europe, the United Kingdom, the United States, Canada, Asia, and Australia [3–9]. The most important contribution of the 2 aforementioned studies appearing in this issue of the Journal is that, for the firs time, a substantial number of individuals without respiratory symptoms were included as controls , and HBoV either was not found or was found very infrequently in this group of individuals. As described in both of these articles, HBoV is a member of the genus Bocavirus and is closely related to parvovirus B19, which also is in the subfamily Parvovirinae in the family Parvoviridae. There are other bocaviruses found in cattle and in dogs; the name " bocavirus " itself is derived from the combination of " bo " (from " bovine ") and " ca " (from " canine "). One of these bocaviruses, bovine parvovirus, primarily causes diarrhea, and the other, minute virus of canines, causes neonatal respiratory disease and embryopathy. The human virus appears to be very common. In the 9 published studies of HBoV, the virus was detected in 1.5%–11.3% of individuals with acute respiratory illness who had respiratory samples screened for HBoV, with a frequency of detection of 5.0%–5.5% noted for most of the studies [1–9]. All of the studies but one [5] have found that the virus is most frequently detected in infants !3 years of age. This frequency of detection makes HBoV less common than respiratory syncytial virus and probably also rhinoviruses in infants with respiratory illnesses; approximately as common as influenz viruses, human metapneu-movirus, parainfluenz virus type 3, and adenoviruses; and probably more common than coronaviruses and …