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Eurosurveillance, Volume 7, Issue 42, 16 October 2003
Articles

Citation style for this article: Winje B, Heldal E, Pettersen FO. Tuberculosis trends in Norway, 2002. Euro Surveill. 2003;7(42):pii=2309. Available online: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=2309

Tuberculosis trends in Norway, 2002

Brita A. Winje (brita.winje@fhi.no), Einar Heldal (einar.heldal@fhi.no) and Frank O. Pettersen (frank.pettersen@fhi.no) Department of Infectious Disease Epidemiology at the Norwegian Institute of Public Health (NIPH).

Two hundred and fifty six cases of tuberculosis were reported in Norway in 2002 (5.7 cases per 100 000 population) (1). This included 208 new cases (with no previous tuberculosis diagnosis) and 48 recurrent cases (with previous tuberculosis diagnosis). Of the 256 patients, 195 patients (76%) were born outside Norway. One hundred and two of the foreign born patients were born in Africa and 63 in Asia. Pulmonary tuberculosis was diagnosed in 61% of all cases.

Transmission of tuberculosis in Norway has been very low for many years, and the majority of Norwegian patients who fall ill were infected prior to the availability of tuberculostatic drugs. The foreign born population in Norway is younger and arrived from countries with a high prevalence of tuberculosis, so the age distribution of their tuberculosis cases is much younger (figure 1).

Figure 1. Notified cases of tuberculosis in Norway 2002 by age, sex and place of birth

Seventy six percent of all the tuberculosis cases, and 77% of the pulmonary cases, were culture positive. Of the 42 isolates from patients born in Norway that were examined for drug resistance in 2002, one was isoniazid resistant and none were multidrug resistant (MDR-TB), that is, showing resistance to both isoniazid and rifampicin. Of the 150 isolates from patients born outside Norway that were examined for drug resistance, 21 showed resistance to isoniazid. Seven of these were also resistant to rifampicin. This is the highest number of MDR-TB ever reported in Norway, representing 2.7 % of all tuberculosis cases.


Trends
The incidence of tuberculosis has steadily decreased in the Norwegian born population. Following increased immigration, the number of reported cases in the foreign born population has increased since the late 1980s, which explains why the overall incidence rate has been unchanged in recent years (figure 2). In subgroups, such as people who were born in Africa, the incidence rate is about as high as it is in these people’s countries of origin (2).

The incidence rate of tuberculosis in Norway is among the lowest in the world. Despite a rise in MDR-TB cases in 2002, it is still a rare condition in Norway. Increased vigilance is needed to prevent these cases by early detection and effective treatment of all tuberculosis patients
One African born patient who was diagnosed with polyresistant tuberculosis (resistant to more than one drug but not to both isoniazid and rifampicin) in 1994 later developed MDR-TB due to poor management. According to fingerprint analysis (RLFP) this case had been the source of 22 secondary cases of polyresistant (nine cases) or MDR-TB (13 cases) by June 2003 (3).

Figure 2. Tuberculosis notifications in Norway 1977-2002 by country of birth

Main prevention strategies
A new national regulation and a manual on the prevention and control of TB came into force at the beginning of 2003 (4,5). Tuberculosis coordinators are appointed at regional level to ensure the implementation of the regulations. These regulations fully comply with the DOTS strategy (http://www.who.int/gtb/dots/index.htm) promoted by the World Health Organization and the International Union Against Tuberculosis and Lung Diseases (IUATLD, http://www.iuatld.org). Directly observed therapy (DOT) is obligatory for all tuberculosis patients throughout the treatment period. Tuberculin skin tests are compulsory for all asylum seekers and other immigrants entering Norway. In addition, chest x ray is compulsory for all immigrants over the age of 15 years. Early diagnosis, combined therapy, and a close follow up of patients during treatment remain the main preventive strategy, in addition to more frequent treatment of latent infection. In addition, much emphasis is put on contact tracing in cases of infectious pulmonary disease. In Norway, contact tracing detects one new tuberculosis case for every ten index cases (5). BCG vaccination was introduced in 1947 and until 1995 was a compulsory part of the national immunisation programme for children at 14 years of age. Since then, BCG vaccine has been a voluntary vaccine, like the rest of vaccines in the programme. The vaccination coverage has remained high, estimated at 99% in 2001. Children in immigrant families are offered BCG vaccine at birth or when they arrive in Norway.

References:
  1. MSIS. Tuberkuløs sykdom meldt i Norge i 2002. MSIS-rapport 2003; 31(23). (http://www.fhi.no/nyhetsbrev/msis/2003/23/) [In Norwegian, accessed 13 October 2003]
  2. Farah MG, Tverdal A, Selmer R, Heldal E, Bjune G. Tuberculosis in Norway by country of birth, 1986-1999. Int J Tuberc Lung Dis 2003; 7(3): 232-5.
  3. Dahle UR, Sandven P, Heldal E, Mannsaaker T, Caugant DA. Deciphering an outbreak of drug-resistant Mycobacterium tuberculosis. J Clin Microbiol 2003; 41(1): 67-72.
  4. Helsedepartementet. 2002-06-21 nr 567: Forskrift om tuberkulosekontroll. (http://www.lovdata.no/for/sf/hd/xd-20020621-0567.html) [In Norwegian, accessed 13 October 2003]
  5. Forebygging og kontroll av tuberkulose. Folkehelseinstituttet 2002. (http://www.fhi.no/filer/pdf/smittevern7-veileder.pdf)[In Norwegian, accessed 13 October 2003]

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