title: The prevalence and risk factors for pneumococcal colonization of the nasopharynx among children in Kilifi District, Kenya.
abstract: BACKGROUND
  Pneumococcal conjugate vaccines (PCV) reduce nasopharyngeal carriage of vaccine-serotype pneumococci but increase in the carriage of non-vaccine serotypes. We studied the epidemiology of carriage among children 3-59 months old before vaccine introduction in Kilifi, Kenya.
  
  
  METHODS
  In a rolling cross-sectional study from October 2006 to December 2008 we approached 3570 healthy children selected at random from the population register of the Kilifi Health and Demographic Surveillance System and 134 HIV-infected children registered at a specialist clinic. A single nasopharyngeal swab was transported in STGG and cultured on gentamicin blood agar. A single colony of pneumococcus was serotyped by Quellung reaction.
  
  
  RESULTS
  Families of 2840 children in the population-based sample and 99 in the HIV-infected sample consented to participate; carriage prevalence was 65.8% (95% CI, 64.0-67.5%) and 76% (95% CI, 66-84%) in the two samples, respectively. Carriage prevalence declined progressively with age from 79% at 6-11 months to 51% at 54-59 months (p<0.0005). Carriage was positively associated with coryza (Odds ratio 2.63, 95%CI 2.12-3.25) and cough (1.55, 95%CI 1.26-1.91) and negatively associated with recent antibiotic use (0.53 95%CI 0.34-0.81). 53 different serotypes were identified and 42% of isolates were of serotypes contained in the 10-valent PCV. Common serotypes declined in prevalence with age while less common serotypes did not.
  
  
  CONCLUSIONS
  Carriage prevalence in children was high, serotypes were diverse, and the majority of strains were of serotypes not represented in the 10-valent PCV. Vaccine introduction in Kenya will provide a natural test of virulence for the many circulating non-vaccine serotypes.
authors.affiliation: Wellcome Trust Research Program, Kenya Medical Research Institute, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya. oabdulla@hsph.harvard.edu
authors.forename: Osman
authors.initials: O
authors.lastname: Abdullahi
authors.forename: Angela
authors.initials: A
authors.lastname: Karani
authors.forename: Caroline C
authors.initials: CC
authors.lastname: Tigoi
authors.forename: Daisy
authors.initials: D
authors.lastname: Mugo
authors.forename: Stella
authors.initials: S
authors.lastname: Kungu
authors.forename: Eva
authors.initials: E
authors.lastname: Wanjiru
authors.forename: Jane
authors.initials: J
authors.lastname: Jomo
authors.forename: Robert
authors.initials: R
authors.lastname: Musyimi
authors.forename: Marc
authors.initials: M
authors.lastname: Lipsitch
authors.forename: J Anthony G
authors.initials: JA
authors.lastname: Scott
mesh_terms: D017677:Age Distribution; D044966:Anti-Retroviral Agents / Q000627:therapeutic use; D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D015169:Colony Count, Microbial; D005260:Female; D015658:HIV Infections / Q000150:complications / Q000188:drug therapy / Q000382:microbiology; D006306:Health Surveys; D006801:Humans; D007223:Infant; D007630:Kenya; D008297:Male; D009305:Nasopharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology*; D015995:Prevalence; D012307:Risk Factors; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000254:growth & development*
chemical_list: D044966:Anti-Retroviral Agents