Clinical and epidemiologic characteristics of human bocavirus in Danish infants - Results from a prospective birth cohort study

Background: Human bocavirus (HBoV) is a recently discovered parvovirus that has been detected in respiratory samples from children with acute respiratory tract infection (ARTI) and in feces from children with gastroenteritis. However, its role as a causative agent of respiratory disease is not determined. Methods: We investigated the presence of HBoV by real-time polymerase-chain reaction of nasal swab specimens obtained from 228 healthy children followed in the community from birth to 1 year of age for a 2-year period from 2004 to 2006. Nasal swabs and symptom diaries were collected at monthly home visits. Results: HBoV was detected in 57 (8.2%) of 697 nasal swab specimens from children with ARTI, in 1 (2.3%) of 44 swabs from children with diarrhea, and in 13 (8.6%) of 152 swabs from asymptomatic children. HBoV was present mainly during the winter months. An additional respiratory virus was identified in 27 (47.4%) HBoV-positive samples. Thirty-four (68%) of 50 children with ARTI shed HBoV for less than I month, 13 (26%) for 2 months, 2 (4%) for 3 months, and 1 (2%) for 4 months. Seven asymptomatic children shed HBoV for less than I month, 2 children for 2 months, and 1 asymptomatic child had 5 HBoV-positive nasal swabs detected for 6 consecutive months. HBoV infection was associated with maternal smoking, being born in the winter, and predisposition to asthma. Conclusions: Asymptornatic carriage of HBoV is common in infants <1 year of age, and an HBoV-positive test result does not imply that HBoV is the cause of the illness.