Journal of Medical Virology 84:253–258 (2012) Human Bocavirus Infection Diagnosed Serologically Among Children Admitted to Hospital With Community-Acquired Pneumonia in a Tropical Region Cristiana M. Nascimento-Carvalho, 1 * Maria-Regina A. Cardoso, 2 Mira Meriluoto, 3 Kaisa Kemppainen, 3 Kalle Kantola, 3 Olli Ruuskanen, 4 Klaus Hedman, 3,5 and Maria So ¨ derlund-Venermo 3 1 Department of Pediatrics, Federal University of Bahia School of Medicine, Salvador, Brazil 2 Department of Epidemiology, Faculty of Public Health, Sa˜o Paulo University, Sa˜o Paulo, Brazil 3 Department of Virology, Haartman Institute, University of Helsinki, Helsinki, Finland 4 Department of Pediatrics, University of Turku, Turku, Finland 5 Department of Virology, Helsinki University Hospital Laboratory Division, Helsinki, Finland Human bocavirus (HBoV) is a human virus as- sociated with respiratory disease in children. Limited information is available on acute infec- tion with HBoV among children admitted to hospital with community-acquired pneumonia in tropical regions and the current diagnosis is inadequate. The aims were to diagnose and describe acute HBoV infections among children hospitalized for community-acquired pneumonia. In Salvador, Brazil, 277 children with community-acquired pneumonia were prospectively enrolled. Paired serum samples were tested by IgG, IgM, and IgG-avidity enzyme immunoassays (EIAs) using recombi- nant HBoV VP2. HBoV DNA was detected in nasopharyngeal aspirates and serum by a quantitative polymerase-chain reaction (PCR). HBoV DNA was detected in nasopharyngeal aspirates of 62/268 (23%) children and 156/273 (57%) were seropositive. Acute primary HBoV infection was reliably diagnosed (bearing at least two acute markers: Positive IgM, a four- fold increase/conversion of IgG, low IgG avidity or viremia) in 21 (8%) of 273 patients, 90% of 20 had HBoV DNA in nasopharyngeal aspirates, 83% with a high DNA load. The median age of infection with HBoV was 16 months, range 5– 36. Community-acquired pneumonia was con- firmed radiographically in 85% of 20 patients with acute HBoV infection diagnosed serologi- cally. HBoV DNA was found in nasopharyngeal aspirates of 42/246(17%) children without an acute primary HBoV infection and available nasopharyngeal aspirate. Four children with HBoV secondary immune responses were detected, lacking both IgM and viremia. HBoV infection was diagnosed accurately in children aged 5–36 months with community-acquired pneumonia confirmed radiographically. PCR of nasopharyngeal aspirates is not a reliable marker of acute HBoV infection. J. Med. Virol. 84:253–258, 2012. ß 2011 Wiley Periodicals, Inc. KEY WORDS: acute respiratory infection; lower respiratory tract infec- tion; respiratory virus; respira- tory tract infection INTRODUCTION Human bocavirus (HBoV) has, since its discovery in 2005 [Allander et al., 2005], been detected in the re- spiratory tract, in symptomatic [Fry et al., 2007] and in healthy children [Martin et al., 2009; Christensen et al., 2010; Martin et al., 2010]. In addition, due to prolonged shedding or persistence in the mucosa co- infections of HBoV with other viruses are diagnosed commonly [Wang et al., 2010] and viral DNA can be detected recurrently for weeks and even months in the respiratory tract of immunocompetent children [von Linstow et al., 2008; Blessing et al., 2009; Martin et al., 2010]. In the light of these findings, the causal Conflict of interest: None. *Correspondence to: Cristiana M. Nascimento-Carvalho, Rua Prof. Aristides Novis, No. 105/1201B, Salvador, CEP 40210-630, Bahia, Brazil. E-mail: nascimentocarvalho@hotmail.com Accepted 28 September 2011 DOI 10.1002/jmv.22268 Published online in Wiley Online Library (wileyonlinelibrary.com). ß 2011 WILEY PERIODICALS, INC.