Nasopharyngeal carriage and transmission of Streptococcus pneumoniae in American Indian households after a decade of pneumococcal conjugate vaccine use.
BACKGROUND
Young children played a major role in pneumococcal nasopharyngeal carriage, acquisition, and transmission in the era before pneumococcal conjugate vaccine (PCV) use. Few studies document pneumococcal household dynamics in the routine-PCV7 era.


METHODS
We investigated age-specific acquisition, household introduction, carriage clearance, and intra-household transmission in a prospective, longitudinal, observational cohort study of pneumococcal nasopharyngeal carriage in 300 American Indian households comprising 1,072 participants between March 2006 and March 2008.


RESULTS
Pneumococcal acquisition rates were 2-6 times higher in children than adults. More household introductions of new pneumococcal strains were attributable to children <9 years than adults ≥17 years (p<0.001), and older children (2-8 years) than younger children (<2 years) (p<0.008). Compared to children <2 years, carriage clearance was more rapid in older children (2-4 years, HRclearance 1.53 [95% CI: 1.22, 1.91]; 5-8 years, HRclearance 1.71 [1.36, 2.15]) and adults (HRclearance 1.75 [1.16, 2.64]). Exposure to serotype-specific carriage in older children (2-8 years) most consistently increased the odds of subsequently acquiring that serotype for other household members.


CONCLUSIONS
In this community with a high burden of pneumococcal colonization and disease and routine PCV7 use, children (particularly older children 2-8 years) drive intra-household pneumococcal transmission: first, by acquiring, introducing, and harboring pneumococcus within the household, and then by transmitting acquired serotypes more efficiently than household members of other ages.
Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
Jonathan F
JF
Mosser
Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
Lindsay R
LR
Grant
Infectious Disease Clinical Research Program, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America.
Eugene V
EV
Millar
Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
Robert C
RC
Weatherholtz
Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
Delois M
DM
Jackson
Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
Bernard
B
Beall
White Mountain Apache Tribe, Whiteriver, Arizona, United States of America.
Mariddie J
MJ
Craig
Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
Raymond
R
Reid
Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
Mathuram
M
Santosham
Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
Katherine L
KL
O'Brien
D000328:Adult; D002353:Carrier State / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control* / Q000635:transmission*; D002648:Child; D002675:Child, Preschool; D005191:Family Characteristics; D005260:Female; D006801:Humans; D007198:Indians, North American; D016015:Logistic Models; D008297:Male; D009305:Nasopharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control* / Q000635:transmission*; D022242:Pneumococcal Vaccines / Q000276:immunology* / Q000600:supply & distribution; D012307:Risk Factors; D013296:Streptococcus pneumoniae / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000276:immunology*
D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate