title: Long-term course of Mycobacterium tuberculosis infection in Swedish birth cohorts during the twentieth century.
abstract: METHODS
  Sweden under transition from high to low tuberculosis (TB) incidence from 1920 to 2009.
  
  
  OBJECTIVE
  To correlate estimates of TB infection in birth cohorts with the longitudinal incidence of active TB to assess the long-term risk and time pattern of reactivated TB.
  
  
  METHODS
  Time trend analysis on TB incidence using age-cohort modelling.
  
  
  RESULTS
  The overall TB incidence decreased from 700 per 100,000 population in 1920 to 1.4 in 2009 in the Sweden-born population. The estimated disease rate (number of cases divided by the estimated number of infected in 1967), for each birth cohort between 1920 and 1940, was stable on a level between 9.8% and 10.7%. The reactivation rate of latent TB infection (LTBI) was 2% after 1967, when indigenous transmission had disappeared.
  
  
  CONCLUSIONS
  Although approximately 10% of persons with LTBI developed active TB, the majority of cases occurred shortly after infection, and the rates of reactivation declined over time. This indicates extensive spontaneous clearance of LTBI.
authors.affiliation: Infectious Disease Research Unit, Department of Clinical Sciences, Lund University, Malmö University Hospital, Malmö, Sweden. Niclas.Winqvist@skane.se
authors.forename: N
authors.initials: N
authors.lastname: Winqvist
authors.forename: J
authors.initials: J
authors.lastname: Björk
authors.forename: H
authors.initials: H
authors.lastname: Miörner
authors.forename: P
authors.initials: P
authors.lastname: Björkman
mesh_terms: D015988:Cohort Effect; D015331:Cohort Studies; D016208:Databases, Factual; D049673:History, 20th Century; D006801:Humans; D015994:Incidence; D012307:Risk Factors; D017678:Sex Distribution; D013548:Sweden / Q000453:epidemiology; D014376:Tuberculosis / Q000453:epidemiology / Q000266:history*