title: In very young infants severity of acute bronchiolitis depends on carried viruses.
abstract: BACKGROUND
  RT amplification reaction has revealed that various single viruses or viral co-infections caused acute bronchiolitis in infants, and RV appeared to have a growing involvement in early respiratory diseases. Because remaining controversial, the objective was to determine prospectively the respective role of RSV, RV, hMPV and co-infections on the severity of acute bronchiolitis in very young infants.
  
  
  RESULTS
  209 infants (median age: 2.4 months) were enrolled in a prospective study of infants <1 year old, hospitalized for a first episode of bronchiolitis during the winter epidemic season and with no high risk for severe disease. The severity was assessed by recording SaO(2)% at admission, a daily clinical score (scale 0-18), the duration of oxygen supplementation and the length of hospitalization. Viruses were identified in 94.7% by RT amplification reaction: RSV only (45.8%), RV only (7.2%), hMPV only (3.8%), dual RSV/RV (14.3%), and other virus only (2%) or coinfections (9%). RV compared respectively with RSV and dual RSV/RV infection caused a significant less severe disease with a lower clinical score (5[3.2-6] vs. 6[4-8], p = 0.01 and 5.5[5-7], p = 0.04), a shorter time in oxygen supplementation (0[0-1] days vs. 2[0-3] days, p = 0.02 and 2[0-3] days, p = 0.03) and a shorter hospital stay (3[3-4.7] days vs.6 [5-8] days, p = 0.001 and 5[4-6] days, p = 0.04). Conversely, RSV infants had also longer duration of hospitalization in comparison with RSV/RV (p = 0.01) and hMPV (p = 0.04). The multivariate analyses showed that the type of virus carried was independently associated with the duration of hospitalization.
  
  
  CONCLUSIONS
  This study underlined the role of RV in early respiratory diseases, as frequently carried by young infants with a first acute bronchiolitis. RSV caused the more severe disease and conversely RV the lesser severity. No additional effect of dual RSV/RV infection was observed on the severity.
authors.affiliation: Respiratory Diseases, Allergy and CF Unit, Pediatric Department, Rouen University Hospital Charles Nicolle, Rouen, France. christophe.marguet@chu-rouen.fr
authors.forename: Christophe
authors.initials: C
authors.lastname: Marguet
authors.forename: Marc
authors.initials: M
authors.lastname: Lubrano
authors.forename: Marie
authors.initials: M
authors.lastname: Gueudin
authors.forename: Pascal
authors.initials: P
authors.lastname: Le Roux
authors.forename: Antoine
authors.initials: A
authors.lastname: Deschildre
authors.forename: Chantal
authors.initials: C
authors.lastname: Forget
authors.forename: Laure
authors.initials: L
authors.lastname: Couderc
authors.forename: Daniel
authors.initials: D
authors.lastname: Siret
authors.forename: Marie-Dominique
authors.initials: MD
authors.lastname: Donnou
authors.forename: Michael
authors.initials: M
authors.lastname: Bubenheim
authors.forename: Astrid
authors.initials: A
authors.lastname: Vabret
authors.forename: François
authors.initials: F
authors.lastname: Freymuth
mesh_terms: D000208:Acute Disease; D001988:Bronchiolitis / Q000473:pathology / Q000821:virology*; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007902:Length of Stay; D029121:Metapneumovirus / Q000302:isolation & purification; D011446:Prospective Studies; D018113:Respiratory Syncytial Virus, Human / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014780:Viruses / Q000302:isolation & purification*