Epidemiological basis of tuberculosis eradication in an advanced country.

The first section of the report provides a background for the long-range epidemiological studies being conducted by the Danish Tuberculosis Index. An outline is given of the main indices of tuberculosis and the changing tuberculosis situation in Denmark during the past several decades with respect to prevalence of infection, morbidity and mortality. Difficulties encountered in international comparisons are briefly discussed. The prevalence of tuberculous infection in children and the prevalence of bacillary cases of pulmonary tuberculosis in adults are suggested as the most valuable indices of eradication.The second section describes the nation-wide mass campaign of 1950-52, which was planned and conducted as a combined service and research programme under the direction of the Danish Tuberculosis Index. With a view to the follow-up studies, details are given of the results of tuberculin tests of the unvaccinated, the documented vaccinated and mixed groups in the population examined. A survey is made of the results of X-ray examination and of the relation between vaccination status, tuberculin reaction and X-ray findings.The results of the first follow-up period are analysed in the final section of the report in terms of new cases of pulmonary tuberculosis appearing in the adult population. Seventy-five per cent of the new cases appeared among the unvaccinated tuberculin-positive population, and among this population groups of persons with widely different risks of developing tuberculosis could be identified on the basis of X-ray findings and reactions to the intradermal 10 TU tuberculin test. A proposal is made to reduce the number of routine repetitive examinations for adults and to concentrate efforts on preventive measures for the high-risk groups.