title: Comparing Human Metapneumovirus and Respiratory Syncytial Virus: Viral Co-Detections, Genotypes and Risk Factors for Severe Disease.
abstract: BACKGROUND
  It is unclarified as to whether viral co-detection and human metapneumovirus (HMPV) genotypes relate to clinical manifestations in children with HMPV and lower respiratory tract infection (LRTI), and if the clinical course and risk factors for severe LRTI differ between HMPV and respiratory syncytial virus (RSV).
  
  
  METHODS
  We prospectively enrolled hospitalized children aged <16 years with LRTI from 2006 to 2015. Children were clinically examined, and nasopharyngeal aspirates were analyzed using semi-quantitative, real-time polymerase chain reaction tests for HMPV, RSV and 17 other pathogens. HMPV-positive samples were genotyped.
  
  
  RESULTS
  A total of 171 children had HMPV infection. HMPV-infected children with single virus (n = 106) and co-detections (n = 65) had similar clinical manifestations. No clinical differences were found between HMPV genotypes A (n = 67) and B (n = 80). The HMPV-infected children were older (median 17.2 months) than RSV-infected children (median 7.3 months, n = 859). Among single virus-infected children, no differences in age-adjusted LRTI diagnoses were found between HMPV and RSV. Age was an important factor for disease severity among single virus-infected children, where children <6 months old with HMPV had a milder disease than those with RSV, while in children 12-23 months old, the pattern was the opposite. In multivariable logistic regression analysis for each virus type, age ≥12 months (HMPV), and age <6 months (RSV), prematurity, ≥1 chronic disease and high viral loads of RSV, but not high HMPV viral loads, were risk factors for severe disease.
  
  
  CONCLUSIONS
  Among hospitalized children with LRTI, HMPV manifests independently of viral co-detections and HMPV genotypes. Disease severity in HMPV- and RSV-infected children varies in relation to age. A history of prematurity and chronic disease increases the risk of severe LRTI among HMPV- and RSV-infected children.
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Pediatrics, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
authors.forename: Nina
authors.initials: N
authors.lastname: Moe
authors.affiliation: Department of Medical Microbiology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
authors.forename: Sidsel
authors.initials: S
authors.lastname: Krokstad
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Inger Heimdal
authors.initials: IH
authors.lastname: Stenseng
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Medical Microbiology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
authors.forename: Andreas
authors.initials: A
authors.lastname: Christensen
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Pediatrics, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
authors.forename: Lars Høsøien
authors.initials: LH
authors.lastname: Skanke
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Pediatrics, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
authors.forename: Kari Ravndal
authors.initials: KR
authors.lastname: Risnes
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Medical Microbiology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
authors.forename: Svein Arne
authors.initials: SA
authors.lastname: Nordbø
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Pediatrics, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
authors.forename: Henrik
authors.initials: H
authors.lastname: Døllner
mesh_terms: D002673:Child, Hospitalized; D002675:Child, Preschool; D060085:Coinfection / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D004279:DNA, Viral / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D029121:Metapneumovirus / Q000235:genetics / Q000302:isolation & purification*; D009664:Norway / Q000453:epidemiology; D018184:Paramyxoviridae Infections / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D015995:Prevalence; D011446:Prospective Studies; D018357:Respiratory Syncytial Virus Infections / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D018113:Respiratory Syncytial Virus, Human / Q000235:genetics / Q000302:isolation & purification*; D012141:Respiratory Tract Infections / Q000821:virology*; D012307:Risk Factors; D012720:Severity of Illness Index
chemical_list: D004279:DNA, Viral