Impact of immigration on tuberculosis epidemiology in a low-incidence country

Authors

  • E. Svensson,

    1.  Institute for Biomedicine, University of Gothenburg, Gothenburg, Sweden
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  • J. Millet,

    1.  Unité de la Tuberculose et des Mycobactéries, Institut Pasteur de Guadeloupe, Guadeloupe, France,
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  • A. Lindqvist,

    1.  Department of Communicable Disease Control and Prevention, Västra Götaland, Sweden
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  • M. Olsson,

    1.  Department of Communicable Disease Control and Prevention, Västra Götaland, Sweden
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  • M. Ridell,

    1.  Institute for Biomedicine, University of Gothenburg, Gothenburg, Sweden
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  • N. Rastogi,

    1.  Unité de la Tuberculose et des Mycobactéries, Institut Pasteur de Guadeloupe, Guadeloupe, France,
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  • The Western Sweden Tuberculosis Epidemiology Study Group

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    • Members of the western Sweden tuberculosis epidemiology study group were: C. Welinder-Olsson, Institute of Biomedicine; M. Wahl and L. Dotevall, Department of Communicable Disease Control and Prevention of Västra Götaland; L. Grettve, M. Berndtson, T. Månsson and H. Fjällbrant, Departments of Medicine, Sections of Pulmonology at the hospitals in Trollhättan, Borås, Skövde, and Gothenburg, respectively; and C. Säll, Infectious Diseases Department, Borås, Sweden.


Corresponding author: E. Svensson, Department of Clinical Bacteriology, Sahlgrenska University Hospital, Box 7193, SE-402 34 Gothenburg, Sweden
E-mail: erik.svensson@vgregion.se

Abstract

Clin Microbiol Infect 2011; 17: 881–887

Abstract

Mycobacterium tuberculosis strains from 349 patients were isolated in western Sweden during the years 2001–2005. Only 26% of the tuberculosis (TB) patients were born in Sweden. All the others were born in any of 42 different countries; 17% in other European countries, 28% in Africa, 16% in Asia, 11% in the Middle East, and 2% in South America. The mean age of the Swedish-born patients was 67 years, while the mean age among the foreign-born patients was 37 years. The male/female ratio was 1.6 among the Swedes and 0.9 among those born abroad. Extrapulmonary manifestations of TB were most common among patients born in Africa while lung infections without extrapulmonary manifestations were most common in patients born in Europe, including Sweden. Spoligotyping showed that patients with T or Beijing strains had more pulmonary TB than extrapulmonary TB, while patients with EAI and CAS strains had a high proportion of extrapulmonary TB. The ancestral and/or evolutionary older PGG1 strains were more often isolated from the foreign-born patients than from the Swedish-born patients, who had strains generally being of the evolutionary recent genogroups PGG2/PGG3. We conclude that immigration from countries with a high incidence of TB has a strong impact on the TB epidemiology in western Sweden, a finding that should be taken into account by TB control strategists when developing programmes for eradication of TB in low prevalence settings.

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