title: Human metapneumovirus viral load is an important risk factor for disease severity in young children.
abstract: BACKGROUND
  The role of viral load in human metapneumovirus (HMPV) disease severity has not yet been clearly determined.
  
  
  OBJECTIVE
  We evaluated the importance of viral load along with other factors in HMPV disease severity among children aged <3 years old.
  
  
  METHODS
  HMPV-positive cases were selected from a cohort of outpatients and hospitalized children with lower respiratory tract infections. HMPV groups (A or B) and viral loads were determined in their nasopharyngeal aspirates. Disease severity was defined by assessing risk for hospitalization and by using two validated clinical severity scores.
  
  
  RESULTS
  Of the 118 HMPV cases detected over 4 years for which viral load could be determined, 60 belonged to genotype A and 58 to genotype B. Baseline characteristics were similar in HMPV-A and HMPV-B mono-infected patients. In multivariate analysis, HMPV hospitalization was associated with viral load ≥1000 copies/10(4)cells (OR, 3.2; 95%CI, 1.4-7.4), age <6 months (OR, 3.1; 95%CI, 1.2-8.6) and presence of ≥3 children in the household (OR, 2.7; 95%CI, 1.04-6.9). A high HMPV viral load was also associated with pulmonary rales (p=.03), use of bronchodilators (p=.02) and inhaled corticosteroids (p=.01).
  
  
  CONCLUSIONS
  HMPV viral load is associated with disease severity in young children along with young age and household crowding.
authors.affiliation: Research Center in Infectious Diseases of the CHU of Québec and Laval University, Quebec City, QC, Canada.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Roussy
authors.affiliation: Research Center in Infectious Diseases of the CHU of Québec and Laval University, Quebec City, QC, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Carbonneau
authors.affiliation: Institut National de Santé Publique du Québec, Quebec City, QC, Canada.
authors.forename: Manale
authors.initials: M
authors.lastname: Ouakki
authors.affiliation: McGill University Health Centre, Montréal, QC, Canada.
authors.forename: Jesse
authors.initials: J
authors.lastname: Papenburg
authors.affiliation: Research Center in Infectious Diseases of the CHU of Québec and Laval University, Quebec City, QC, Canada.
authors.forename: Marie-Ève
authors.initials: MÈ
authors.lastname: Hamelin
authors.affiliation: Institut National de Santé Publique du Québec, Quebec City, QC, Canada.
authors.forename: Gaston
authors.initials: G
authors.lastname: De Serres
authors.affiliation: Research Center in Infectious Diseases of the CHU of Québec and Laval University, Quebec City, QC, Canada. Electronic address: Guy.Boivin@crchul.ulaval.ca.
authors.forename: Guy
authors.initials: G
authors.lastname: Boivin
mesh_terms: D002675:Child, Preschool; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D029121:Metapneumovirus / Q000302:isolation & purification*; D009305:Nasopharynx / Q000821:virology; D018184:Paramyxoviridae Infections / Q000473:pathology* / Q000821:virology*; D011446:Prospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D019562:Viral Load
keywords: Hospitalization; Human metapneumovirus; Pediatric; Severity; Viral load