[Tuberculosis among children in Denmark, 1990-1999]

Abstract

Introduction: During a century with a decreasing incidence of tuberculosis (TB) in Denmark, the last 15 years have seen an increase. We describe the epidemiology of TB in children in Denmark with the focus on the impact of immigration.

Materials and methods: Data from the national TB surveillance of 1990-1999 were analysed. The variables were age, gender, nationality, TB location(s), and the results of microscopy and culture.

Results: Three hundred and forty-nine children below 15 years of age were found, representing 8% of all notified cases of TB. Of these, 268 children (78%) were immigrants. The number of children increased over time, as did the proportion of immigrants (p < 0.0001). The median age was four years in the native Danes and nine years in the immigrant children (p < 0.001). The mean annual incidence of TB in the children was 3.9 per 10(5); 45.8 per 10(5) in the immigrants and 0.92 per 10(5) in the native Danes. The incidence increased from 2.0 in 1990 to 5.3 per 10(5) in 1999. Forty-nine per cent of the immigrants were Somalis, 13% were Pakistanis. The mean annual TB incidence was 581 per 10(5) in Somalis and 78 per 10(5) in Pakistanis. The incidence increased with age in children from Pakistan and Somalia and decreased in native Danes. Seventy-seven per cent of native Danes and 65% of immigrants had pulmonary TB +/- other locations (p < 0.05). Sixty-seven per cent of immigrant children with extrapulmonary TB had TB in the glands, 9% had TB in the bones, and another 9% had TB in the digestive system, proportions that were 38% (p < 0.05), 8%, and 0%, respectively, in native Danes.

Discussion: Immigration has had an impact on the incidence of TB, as well as on the pattern of TB location in children in Denmark. The incidence was 48 times higher in immigrant than in native Danish children.