title: Risk of infection with Mycobacterium tuberculosis in travellers to areas of high tuberculosis endemicity.
abstract: BACKGROUND
  No data exist on risks of infection with Mycobacterium tuberculosis in travellers. We studied incidences of and risk factors for tuberculin skin-test conversion among Dutch long-term travellers to countries of high tuberculosis endemicity.
  
  
  METHODS
  In a multicentre, prospective cohort study based in travel and tuberculosis clinics in the Netherlands, 1072 BCG-naive immunocompetent travellers to countries with an estimated annual risk of M. tuberculosis infection of at least 1% were skin tested before departure with 1 tuberculin unit purified protein derivative (PPD) of M. tuberculosis in Tween-80. Those with results less than 2 mm were retested 2-4 months after their return with simultaneous testing for cross-sensitivity to environmental mycobacteria (1 tuberculin unit PPD of M. scrofulaceum in Tween-80). M. tuberculosis infection was defined as a post-travel M. tuberculosis tuberculin skin-test result of at least 10 mm that was 3 mm or more larger than the M. scrofulaceum result.
  
  
  RESULTS
  Post-travel skin-test results were available for 656 (66%) of 988 individuals who were eligible for follow-up. Among these, 12 M. tuberculosis infections were identified (1.8%). The overall incidence rate was 3.5 per 1000 person-months of travel (95% CI 2.0-6.2), and 2.8 per 1000 person-months of travel (1.2-5.5) after exclusion of health-care workers. Two had active tuberculosis at the time of testing (incidence rate 0.6 per 1000 person-months of travel [0.3-2.3]). Work in patient care abroad was an independent risk factor (adjusted rate ratio 5.34, p=0.015).
  
  
  CONCLUSIONS
  The risk of M. tuberculosis infection in long-term travellers to high-endemicity countries, even if not engaged in health-care work, is substantial and of similar magnitude to the average risk for the local population. BCG vaccination or post-travel tuberculin skin-testing of high-risk travellers should be considered.
authors.affiliation: Division of Infectious Diseases, Tropical Medicine and AIDS, Academic Medical Center, Amsterdam, The Netherlands. f.g.cobelens@amc.uva.nl
authors.forename: F G
authors.initials: FG
authors.lastname: Cobelens
authors.forename: H
authors.initials: H
authors.lastname: van Deutekom
authors.forename: I W
authors.initials: IW
authors.lastname: Draayer-Jansen
authors.forename: A C
authors.initials: AC
authors.lastname: Schepp-Beelen
authors.forename: P J
authors.initials: PJ
authors.lastname: van Gerven
authors.forename: R P
authors.initials: RP
authors.lastname: van Kessel
authors.forename: M E
authors.initials: ME
authors.lastname: Mensen
mesh_terms: D000328:Adult; D019353:Endemic Diseases; D014943:Global Health; D006801:Humans; D011446:Prospective Studies; D012882:Skin Tests; D014195:Travel; D014376:Tuberculosis / Q000175:diagnosis / Q000453:epidemiology*