No 49 - 2011

Tuberculosis 2010, part I

2010 saw a total of 359 notified cases of tuberculosis (TB), 130 (36%) in persons of Danish origin and 229 (64%) in immigrants or descendants. The overall incidence was 6.5 per 10⁵.

The M/F ratio was 1.8 for Danes and 1.2 for immigrants. The median age was 49 years (1-85 years) for Danes and 37 years (range 2-83 years) for immigrants. Table 1 shows the distribution by part of country and origin.

A total of 46 (13%) patients were notified with recurrence, including 18 Greenlanders, nine Danes, eight Somalies, two Filipinoes and one person from each of the following: the Faroe Islands, Poland, Romania, India, Thailand and Cambodia. In three cases, the country of origin was unknown.

Alcohol abuse and/or homelessness were noted for 53 patients (15%) of whom 26 were Danes and 27 immigrants. Among the immigrants, 16 were of Greenlandic origin.
Information on concurrent HIV infection and therefore AIDS was provided in nine cases: two Danes and seven immigrants. Table 2 shows the distribution by TB localization and part of country.

Country of infection and ethnicity

On the basis of the notifications, a total of 146 cases were presumably infected in Denmark, including 109 of Danish origin. A total of 37 immigrants were presumably infected in Denmark, including 20 from Greenland, six from Somalia and the remaining 11 cases from nine other countries. Six Danes were presumably infected in Africa (1), Asia (4) or South America (1). In the remaining 15 Danes, the country of infection was unknown.

A total of 117 immigrants were presumably infected in their country of origin, including 21 Somalis, 20 Greenlanders, 11 Filipinoes, 10 Thailanders, nine Indians, seven Romanians and six Pakistanis. For a total of 75 immigrants, the country of infection was unknown.

TB in children

A total of 20 cases of TB in children below the age of 15 years were notified, including eight (40%) below the age of five years. Half of the children (10) were Danes; all had been infected in Denmark. Among the 10 immigrant children, eight (40%) were presumably infected in Denmark and the remaining six (60%) in their parent's countries of origin.

A total of five (25%) children, including three Danish, were probably infected by a family member who had suffered from TB within the past three years. Two Danish children had had contact to a person, who had suffered from TB within a three-year period, while one immigrant child had been in contact with a person who had had TB more than three years ago. For a total of 12 children, the source of infection was unknown or not stated.

A total of 18 (90%) children, including nine Danes and 12 immigrants, had pulmonary TB. One immigrant child had cerebral TB and one Danish child had glandular TB.

Occupational infection

A total of eight cases were registered as presumably occupational infections, six Danes and two immigrants. Seven had positive cultures, for which DNA typing by MIRU-VNTR method was possible, EPI-NEWS 50/10.

A Danish male had worked in Africa as well as in Asia. DNA typing showed a unique pattern, which raises the probability of infection outside of Denmark.

One Danish male had previously been exposed to TB in the armed forces. DNA typing showed 11 other persons in the same cluster, but occupational infection could not be further substantiated.

One Danish male had been employed in a kindergarten with many children of foreign origin, but no known exposure. DNA typing showed a unique pattern which makes infection in Denmark unlikely.

A non-Danish veterinarian was probably infected with Mycobacterium bovis while working at an abattoir in his country of origin. DNA typing was not available, but as M. bovis is rare in humans, infection via cattle is likely.

A non-Danish male was possibly exposed to TB as a seaman. DNA typing showed a unique pattern which makes infection abroad likely.

A Danish female was probably infected via her work as health staff at a hospital where she was in regular contact with TB patients. DNA typing showed three other patients in the same cluster. On the basis of information about these patients admission for TB, occupational infection was deemed likely.

Another Danish female was possibly infected occupationally while working as health staff at a hospital. DNA typing showed that only one more person had the same pattern. Once additional information had been gathered, occupational infection was deemed likely.

(P.H. Andersen, Dept. of Epidemiology, T. Lillebæk, National Dept. for TB and mycobacteria) 

Comments will follow in part II.

7 December 2011