title: Seasonality of Pneumococcal Nasopharyngeal Carriage in Rural Gambia Determined within the Context of a Cluster Randomized Pneumococcal Vaccine Trial.
abstract: BACKGROUND
  We conducted an ancillary study among individuals who had participated in a PCV-7 trial in rural Gambia, to determine the influence of season on the prevalence of pneumococcal carriage.
  
  
  METHODS
  636 individuals above 30 months of age were followed from 4 to 20 months after vaccination with PCV-7 or meningococcal-conjugate-vaccine. Nasopharyngeal swabs were collected periodically between November 2006 and June 2008. Overall, 4,495 NPS were collected.
  
  
  RESULTS
  Prevalence of pneumococcal nasopharyngeal carriage in the study subjects (median age 11 years) was 55.0%; this prevalence decreased linearly with increasing age (p = 0.001). Prevalence of carriage was significantly higher during the dry than the rainy season for any pneumococcal carriage [57.6% versus 47.8% (p<0.001)], pneumococcal vaccine serotype carriage [10.3% versus 6.5% (p< 0.001)] and non-vaccine serotype carriage [49.7% versus 42.7% (p<0.001)]. Differences remained significant in the adjusted analysis.
  
  
  CONCLUSIONS
  In areas of Africa with marked variation in rainfall, seasonality of pneumococcal carriage needs to be considered when interpreting carriage data.
authors.affiliation: Medical Research Council Unit, Fajara, The Gambia.
authors.forename: Abdoulie
authors.initials: A
authors.lastname: Bojang
authors.affiliation: Medical Research Council Unit, Fajara, The Gambia.
authors.forename: James
authors.initials: J
authors.lastname: Jafali
authors.affiliation: Medical Research Council Unit, Fajara, The Gambia.
authors.forename: Uzochukwu E
authors.initials: UE
authors.lastname: Egere
authors.affiliation: Medical Research Council Unit, Fajara, The Gambia; Centre for International Health, School of Medicine, University of Otago, Dunedin, New Zealand.
authors.forename: Phillip C
authors.initials: PC
authors.lastname: Hill
authors.affiliation: Medical Research Council Unit, Fajara, The Gambia.
authors.forename: Martin
authors.initials: M
authors.lastname: Antonio
authors.affiliation: Medical Research Council Unit, Fajara, The Gambia.
authors.forename: David
authors.initials: D
authors.lastname: Jeffries
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Greenwood
authors.affiliation: Medical Research Council Unit, Fajara, The Gambia.
authors.forename: Anna
authors.initials: A
authors.lastname: Roca
mesh_terms: D000293:Adolescent; D002353:Carrier State / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005714:Gambia / Q000453:epidemiology; D000069443:Heptavalent Pneumococcal Conjugate Vaccine / Q000276:immunology; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009305:Nasopharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000382:microbiology* / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000276:immunology; D015995:Prevalence; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D012621:Seasons; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification / Q000276:immunology* / Q000302:isolation & purification; D014611:Vaccination
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines