Prevalence of Human Bocavirus in infants and pre-school children with lower acute respirtory disease in Cordoba, Argentina: 5-year follow-up study, 2007-2011

GHIETTO LUCÍA; MORENO LAURA; EGUIZÁBAL LETICIA; SUAREZ MARÍA; BARRETO CLAUDIA; POLO CONSTANZA; ADAMO M. PILAR

Daytona Beach, Florida

Simposio; 28th Clinical Virology Symposium; 2012

Panamerican Society for Clinical Virology

Introduction: Human Bocavirus(HBoV) frequency in children younger than 5 years old with lower respiratory tract disease (bronchiolitis or pneumonia) in Córdoba, Argentina, averaged 21% in 2007 ? 2009. To complete a 5-year record of HBoV, we report the detection of the virus in pediatric patients hospitalized with lower acute respiratory infection during 2010 and 2011, and describe its circulation from 2007 through 2011. Methods: Respiratory specimens were collected from patients ≤ 5 years old hospitalized with a diagnosis of bronchiolitis or pneumonia, from January through December 2011 (n = 286). All available stored samples obtained during January through December 2010 (n = 144) from children with the same inclusion criteria were also analyzed. Nucleic acids were extracted from 50 µl nasopharyngeal aspirate or 100 µl cell suspension from nasopharyngeal swab with guanidine and silica. HBoV genome was detected by PCR in 2 µl sample template with primers for NP1. Sequence analysis was performed using the complete NP1 region. Annual HBoV circulation and frequency per age subgroups were examined over the past 5 years, plotting HBoV positive (HBoV+) cases in 2010 and 2011 together with local previous data from 2007 to 2009 (Ghietto et al., Braz J Infec Dis 16:38-44). The study was approved by the Institutional Ethics Committee (CIEIS Polo Hospitalario del Niño y el Adulto, Hospital de Niños de Córdoba) and prospective samples collected during 2011 were obtained after informed consent signed by parents or tutors. Results: The prevalence of HBoV in 2007 through 2011 is shown in the table: 2007 2008 2009 2010 2011 Prevalence 16/100 (16.0%) 9/33 (27.3%) 68/300 (22.7%) 22/144 (15.3%) 16/286 (5.6%) Epidemiological week range 13 to 44 21 to 36 25 to 48 1 to 36 11 to 43 Epidemiological weeks of higher frequency 21 to 28* 29 to 36* 25 to 36* 29 to 36* 21 to 36* Age range of HBoV+ patients 0.5 ? 48 mo. 1 ? 14 mo. 0.3 ? 60 mo. 0.3 ? 36 mo. 0.3 ? 51 mo. HBoV+ patients ≤1 yr old 14/16 (87.5%) 8/9 (88.9%) 65/68 (95.6%) 17/22 (77.3%) 15/16 (93.8%) *winter season. HBoV genome detection was consistently predominant in infants ≤1 year old along all the period considered. All 26 viral isolates sequenced (strains from 2007, 2009, 2010 and 2011) clustered with HBoV1. Conclusions: HBoV1 was detected mainly among infants younger than 1 year old in the population studied and appears to present a pattern similar to that of other respiratory viruses with seasonal peaks in winter every year. Without considering 2008 due to the limited number of available samples, data suggest that epidemic peaks of greater magnitude likely occur, as seen during 2009.