title: Epidemiology of viral respiratory tract infections in a prospective cohort of infants and toddlers attending daycare.
abstract: BACKGROUND
  The epidemiology of respiratory tract infections (RTIs) in a daycare cohort has not been explored using molecular techniques.
  
  
  OBJECTIVE
  (1) Determine the overall incidence of RTIs in a daycare cohort using real-time reverse transcriptase polymerase chain reaction (RT-PCR). (2) Determine the relative incidence and impact of specific respiratory viruses, and characterize and compare clinical features associated with these pathogens.
  
  
  METHODS
  In this prospective cohort study conducted from February 2006 to April 2008, nasal swabs were obtained from symptomatic children ages 0-30 months enrolled in fulltime daycare. RT-PCR was performed to detect respiratory syncytial virus (RSV), human metapneumovirus (MPV), influenza (Flu) viruses A and B, parainfluenza (PIV), adenovirus (AdV), human coronaviruses (CoV) and rhinovirus (RhV). Symptom diaries were completed for each illness.
  
  
  RESULTS
  We followed 119 children (mean age 10 months; range 2-24 months) for 115 child years. The mean annual incidence of RTI per child was 4.2 the first year and 1.2 the second year of the study. At least 1 virus was identified in 67% RTIs. Co-infections were common (27% RTIs), with RhV, CoV, and AdV the most common co-pathogens. PIV was identified in 12% of RTIs with a high incidence of PIV4. The viruses with the greatest impact on our population were RSV, RhV and AdV.
  
  
  CONCLUSIONS
  Using molecular techniques, viruses were identified in approximately twice as many RTIs as previously reported in a daycare cohort. Infections with newly identified viruses, such as HMPV and CoV subtypes were less frequent and severe than infections with RSV, AdV and RhV.
authors.affiliation: Department of Pediatrics, Madigan Army Medical Center, BLDG 9040 Fitzsimmons Drive, Tacoma, WA 98431, United States. fairchokmp@hotmail.com
authors.forename: Mary P
authors.initials: MP
authors.lastname: Fairchok
authors.forename: Emily T
authors.initials: ET
authors.lastname: Martin
authors.forename: Susan
authors.initials: S
authors.lastname: Chambers
authors.forename: Jane
authors.initials: J
authors.lastname: Kuypers
authors.forename: Melinda
authors.initials: M
authors.lastname: Behrens
authors.forename: Loranee E
authors.initials: LE
authors.lastname: Braun
authors.forename: Janet A
authors.initials: JA
authors.lastname: Englund
mesh_terms: D000256:Adenoviridae / Q000235:genetics / Q000302:isolation & purification; D002656:Child Day Care Centers / Q000706:statistics & numerical data*; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011446:Prospective Studies; D018113:Respiratory Syncytial Virus, Human / Q000235:genetics / Q000302:isolation & purification; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000821:virology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012229:Rhinovirus / Q000235:genetics / Q000302:isolation & purification; D014777:Virus Diseases / Q000453:epidemiology* / Q000821:virology*