title: Local epidemic history as a predictor of tuberculosis incidence in Saskatchewan Aboriginal communities.
abstract: BACKGROUND
  Average tuberculosis (TB) incidence rates are high in Canadian Aboriginal communities, but there is significant variability within this group.
  
  
  OBJECTIVE
  To determine whether local history of post-contact TB epidemics is predictive of contemporary epidemiology among Aboriginal communities in Saskatchewan, Canada.
  
  
  METHODS
  TB incidence, age-specific morbidity patterns and rates of clustering of TB genotypes from 1986 to 2004 were compared between two groups of communities: Group 1, in which post-contact epidemics of TB were established around 1870, and Group 2, in which they were delayed until after 1920. Concomitant effects of socio-economic and geographic variables were explored with multivariate models.
  
  
  RESULTS
  Group 2 communities were characterized by higher annual incidence of TB (median 431 per 100,000 population vs. 38/100,000). In multivariate models that included socio-economic and geographic variables, historical grouping remained a significant independent predictor of community incidence of TB. Clustering of TB genotypes was associated with Group 2 (OR 8.7, 95%CI 3.3-22.7) and age 10-34 years (OR 2.5, 95%CI 1.1-5.7).
  
  
  CONCLUSIONS
  TB transmission dynamics can vary significantly as a function of a population's historical experience with TB. Populations at different stages along the epidemic trajectory may be amenable to different types of interventions.
authors.affiliation: Division of Infectious Diseases, School of Medicine, Stanford University, Stanford, California 94305-5323, USA. pepperc@stanford.edu
authors.forename: C
authors.initials: C
authors.lastname: Pepperell
authors.forename: A H
authors.initials: AH
authors.lastname: Chang
authors.forename: W
authors.initials: W
authors.lastname: Wobeser
authors.forename: J
authors.initials: J
authors.lastname: Parsonnet
authors.forename: V H
authors.initials: VH
authors.lastname: Hoeppner
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D015331:Cohort Studies; D058872:Epidemics / Q000266:history*; D005260:Female; D005838:Genotype; D049672:History, 19th Century; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D015994:Incidence; D007198:Indians, North American / Q000266:history / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000302:isolation & purification; D012189:Retrospective Studies; D012525:Saskatchewan / Q000453:epidemiology; D012959:Socioeconomic Factors; D014376:Tuberculosis / Q000453:epidemiology* / Q000208:ethnology / Q000266:history; D055815:Young Adult