Migrant tuberculosis: the extent of transmission in a low burden country

TY - JOUR

T1 - Migrant tuberculosis: the extent of transmission in a low burden country

AU - Kamper-Jørgensen, Zaza

AU - Andersen, Aase Bengaard

AU - Kok-Jensen, Axel

AU - Kamper-Jørgensen, Mads

AU - Bygbjerg, Ib Christian

AU - Andersen, Peter Henrik

AU - Thomsen, Vibeke Ostergaard

AU - Lillebaek, Troels

PY - 2012/3/18

Y1 - 2012/3/18

N2 - Background: Human migration caused by political unrest, wars and poverty is a major topic in international health. Infectious diseases like tuberculosis follow their host, with potential impact on both the migrants and the population in the recipient countries. In this study, we evaluate Mycobacterium tuberculosis transmission between the national population and migrants in Denmark.Methods: Register study based on IS6110-RFLP results from nationwide genotyping of tuberculosis cases during 1992 through 2004. Cases with 100% identical genotypes were defined as clustered and part of a transmission chain. Origin of clusters involving both Danes and migrants was defined as Danish/migrant/uncertain. Subsequently, the proportion of cases likely infected by the "opposite" ethnic group was estimated.Results: 4,631 cases were included, representing 99% of culture confirmed cases during 1992 through 2004. Migrants contributed 61.6% of cases. Up to 7.9% (95% CI 7.0-8.9) of migrants were infected by Danes. The corresponding figure was 5.8% (95% CI 4.8-7.0) for Danes. Thus, transmission from Danes to migrants occurred up to 2.5 (95% CI 1.8-3.5) times more frequent than vice versa (OR = 1). A dominant strain, Cluster-2, was almost exclusively found in Danes, particular younger-middle-aged males.Conclusions: Transmission between Danes and migrants is limited, and risk of being infected by the "opposite" ethnic group is highest for migrants. TB-control efforts should focus on continues micro-epidemics, e.g. with Cluster-2 in Danes, prevention of reactivation TB in high-risk migrants, and outbreaks in socially marginalized migrants, such as Somalis and Greenlanders. Fears that TB in migrants poses a threat for resident Danes seem exaggerated and unjustified. We believe this to be true for other low incidence countries as well.

AB - Background: Human migration caused by political unrest, wars and poverty is a major topic in international health. Infectious diseases like tuberculosis follow their host, with potential impact on both the migrants and the population in the recipient countries. In this study, we evaluate Mycobacterium tuberculosis transmission between the national population and migrants in Denmark.Methods: Register study based on IS6110-RFLP results from nationwide genotyping of tuberculosis cases during 1992 through 2004. Cases with 100% identical genotypes were defined as clustered and part of a transmission chain. Origin of clusters involving both Danes and migrants was defined as Danish/migrant/uncertain. Subsequently, the proportion of cases likely infected by the "opposite" ethnic group was estimated.Results: 4,631 cases were included, representing 99% of culture confirmed cases during 1992 through 2004. Migrants contributed 61.6% of cases. Up to 7.9% (95% CI 7.0-8.9) of migrants were infected by Danes. The corresponding figure was 5.8% (95% CI 4.8-7.0) for Danes. Thus, transmission from Danes to migrants occurred up to 2.5 (95% CI 1.8-3.5) times more frequent than vice versa (OR = 1). A dominant strain, Cluster-2, was almost exclusively found in Danes, particular younger-middle-aged males.Conclusions: Transmission between Danes and migrants is limited, and risk of being infected by the "opposite" ethnic group is highest for migrants. TB-control efforts should focus on continues micro-epidemics, e.g. with Cluster-2 in Danes, prevention of reactivation TB in high-risk migrants, and outbreaks in socially marginalized migrants, such as Somalis and Greenlanders. Fears that TB in migrants poses a threat for resident Danes seem exaggerated and unjustified. We believe this to be true for other low incidence countries as well.

KW - Adult

KW - Aged

KW - Aged, 80 and over

KW - Cluster Analysis

KW - DNA Transposable Elements

KW - Denmark

KW - Disease Transmission, Infectious

KW - Female

KW - Genotype

KW - Humans

KW - Male

KW - Middle Aged

KW - Molecular Epidemiology

KW - Molecular Typing

KW - Mycobacterium tuberculosis

KW - Polymorphism, Restriction Fragment Length

KW - Transients and Migrants

KW - Tuberculosis

U2 - 10.1186/1471-2334-12-60

DO - 10.1186/1471-2334-12-60

M3 - Journal article

C2 - 22423983

SN - 1471-2334

VL - 12

JO - B M C Infectious Diseases

JF - B M C Infectious Diseases

M1 - 60

ER -