title: Comparative analysis of Streptococcus pneumoniae transmission in Portuguese and Finnish day-care centres.
abstract: BACKGROUND
  Day-care centre (DCC) attendees play a central role in maintaining the circulation of Streptococcus pneumoniae (pneumococcus) in the population. The prevalence of pneumococcal carriage is highest in DCC attendees but varies across countries and is found to be consistently lower in Finland than in Portugal. We compared key parameters underlying pneumococcal transmission in DCCs to understand which of these contributed to the observed differences in carriage prevalence.
  
  
  METHODS
  Longitudinal data about serotype-specific carriage in DCC attendees in Portugal (47 children in three rooms; mean age 2 years; range 1-3 years) and Finland (91 children in seven rooms; mean age 4 years; range 1-7 years) were analysed with a continuous-time event history model in a Bayesian framework. The monthly rates of within-room transmission, community acquisition and clearing carriage were estimated.
  
  
  RESULTS
  The posterior mean of within-room transmission rate was 1.05 per month (Portugal) vs. 0.63 per month (Finland). The smaller rate of clearance in Portugal (0.57 vs. 0.73 per month) is in accordance with the children being younger. The overall community rate of acquisition was larger in the Portuguese setting (0.25 vs. 0.11 per month), in agreement with that the groups belonged to a larger DCC. The model adequately predicted the observed levels of carriage prevalence and longitudinal patterns in carriage acquisition and clearance.
  
  
  CONCLUSIONS
  The difference in prevalence of carriage (61% in Portuguese vs. 26% among Finnish DCC attendees) was assigned to the longer duration of carriage in younger attendees and a significantly higher rate of within-room transmission and community acquisition in the Portuguese setting.
authors.forename: Delphine
authors.initials: D
authors.lastname: Pessoa
authors.forename: Fabian
authors.initials: F
authors.lastname: Hoti
authors.forename: Ritva
authors.initials: R
authors.lastname: Syrjänen
authors.forename: Raquel
authors.initials: R
authors.lastname: Sá-Leão
authors.forename: Tarja
authors.initials: T
authors.lastname: Kaijalainen
authors.forename: M Gabriela M
authors.initials: MG
authors.lastname: Gomes
authors.forename: Kari
authors.initials: K
authors.lastname: Auranen
mesh_terms: D001499:Bayes Theorem; D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D002648:Child; D002656:Child Day Care Centers / Q000706:statistics & numerical data*; D002675:Child, Preschool; D005387:Finland / Q000453:epidemiology; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission*; D011174:Portugal / Q000453:epidemiology; D015995:Prevalence; D013296:Streptococcus pneumoniae / Q000302:isolation & purification*