TY - JOUR

T1 - Characteristics of non-clustered tuberculosis in a low burden country

AU - Kamper-Jørgensen, Zaza

AU - Andersen, Aase Bengaard

AU - Kok-Jensen, Axel

AU - Bygbjerg, Ib Christian

AU - Thomsen, Vibeke Ostergaard

AU - Lillebaek, Troels

PY - 2012/5/1

Y1 - 2012/5/1

N2 - Molecular genotyping studies often focus on clustered tuberculosis and recent transmission. Less attention has been paid to non-clustered tuberculosis. However, non-clustered cases also contribute significantly to the tuberculosis burden, especially in low-incidence countries. The objective of this study is to characterize non-clustered tuberculosis cases in Denmark and point out potential implications for tuberculosis control. The study is based on nationwide IS6110-RFLP genotyping of tuberculosis cases from 1992 through 2004, corresponding to 98% of culture verified cases. Of 3988 cases, 45% were non-clustered. Both Danes and immigrants had a peak incidence of non-clustered tuberculosis at older ages, 80-89 years (4.3 cases/10 5 population/year) and 60-69 years (28.8 cases/10 5 population/year), respectively. In addition, immigrants had a peak at 20-29 years (43.2 cases/10 5 inhabitants/year). In Danes, the incidence of non-clustered tuberculosis decreased during the study period and was predominantly found in elderly persons, presumably reactivating infection acquired during 1910-40, when tuberculosis incidence was high. In immigrants, the incidence was high at all ages, presumably reflecting reactivation of imported infections. In the future, the number of non-clustered tuberculosis cases will decrease, as older Danes die, and as time since primary infection increases for immigrants residing in Denmark. TB control should include focus on non-clustered cases.

AB - Molecular genotyping studies often focus on clustered tuberculosis and recent transmission. Less attention has been paid to non-clustered tuberculosis. However, non-clustered cases also contribute significantly to the tuberculosis burden, especially in low-incidence countries. The objective of this study is to characterize non-clustered tuberculosis cases in Denmark and point out potential implications for tuberculosis control. The study is based on nationwide IS6110-RFLP genotyping of tuberculosis cases from 1992 through 2004, corresponding to 98% of culture verified cases. Of 3988 cases, 45% were non-clustered. Both Danes and immigrants had a peak incidence of non-clustered tuberculosis at older ages, 80-89 years (4.3 cases/10 5 population/year) and 60-69 years (28.8 cases/10 5 population/year), respectively. In addition, immigrants had a peak at 20-29 years (43.2 cases/10 5 inhabitants/year). In Danes, the incidence of non-clustered tuberculosis decreased during the study period and was predominantly found in elderly persons, presumably reactivating infection acquired during 1910-40, when tuberculosis incidence was high. In immigrants, the incidence was high at all ages, presumably reflecting reactivation of imported infections. In the future, the number of non-clustered tuberculosis cases will decrease, as older Danes die, and as time since primary infection increases for immigrants residing in Denmark. TB control should include focus on non-clustered cases.

KW - Genotyping

KW - IS6110-RFLP

KW - Non-clustered

KW - Reactivation

KW - Tuberculosis

UR - http://www.scopus.com/inward/record.url?scp=84859491769&partnerID=8YFLogxK

U2 - 10.1016/j.tube.2012.02.001

DO - 10.1016/j.tube.2012.02.001

M3 - Journal article

C2 - 22406154

AN - SCOPUS:84859491769

VL - 92

SP - 226

EP - 231

JO - Tuberculosis

JF - Tuberculosis

SN - 1472-9792

IS - 3

ER -