Risk factors for recent transmission of Mycobacterium tuberculosis.

E Heldal,P Sandven,D.A Caugant,D.A Enarson,U.R Dahle,J Kongerud,H.T Waaler,N Brattaas,A Tverdal

doi:10.1183/09031936.03.00019103

Abstract

In recent decades, the decline of tuberculosis has stopped in Western Europe, mainly due to increased immigration from high-prevalence countries. The objective of the current study was to identify risk factors for developing tuberculosis following recent infection, in order to better target interventions. Strains from 861 culture-positive cases, diagnosed in Norway in 1994-1999, were analysed by use of restriction fragment length polymorphism (RFLP). A cluster was defined as two or more isolates with identical RFLP patterns. Risk factors for being part of a cluster were identified by univariate and multivariate analysis. A total of 134 patients were part of a cluster. These constituted 5% Asian-born, 18% Norwegian-born, 24% European-born and 29% African-born patients. Four independent risk factors for being part of a cluster were identified: being born in Norway, being of young age, being infected with an isoniazid-resistant strain and being infected with a multidrug-resistant strain. Transmission of tuberculosis may be further reduced by improving case management, contact tracing, preventive treatment, screening of immigrants and access to health services for the foreign-born population.

Highlights

Risk factors for recent transmission of Mycobacterium tuberculosis
The incidence varied considerably between continents: it was five-times higher in persons born in Europe, 29-times higher in those born in Asia and 92-times higher in those born in Africa, compared with those born in Norway
Being infected with a strain that was resistant to isoniazid or was multidrug resistant were independent risk factors

Summary

Introduction

Risk factors for recent transmission of Mycobacterium tuberculosis. ABSTRACT: In recent decades, the decline of tuberculosis has stopped in Western Europe, mainly due to increased immigration from high-prevalence countries. The objective of the current study was to identify risk factors for developing tuberculosis following recent infection, in order to better target interventions. Four independent risk factors for being part of a cluster were identified: being born in Norway, being of young age, being infected with an isoniazid-resistant strain and being infected with a multidrug-resistant strain. The decline of tuberculosis has stopped in Western Europe. This is mainly linked to increased immigration from countries with a high prevalence of tuberculosis, illustrating that tuberculosis is of growing concern globally. Tuberculosis services should, focus on such groups with the greatest risk of developing tuberculosis

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Conclusion