[Fifty years of research on tuberculosis. Lessons I have learnt during 50 years and topics to be investigated in the future].

I have engaged in the research on tuberculosis for 50 years, and lessons I have learnt during this period could be summarized in the following ten topics. First is great research achievements by our predecessors on the establishment of so-called primary infection theory on the pathogenesis of TB, planning of TB control principles based on the theory and development of new technologies used for TB control, such as mass miniature X-ray examination and BCG vaccination in 1920s and 1930s. TB control law was enforced in 1951, and the modern TB programme was initiated. Second, the field is a treasure house of interesting data. Several interesting data on TB soon after the World War II in Tokyo and a rural area were collected and analyzed from the mass health examination. Third, looking at the increase of tuberculin positivity with age, it was found that the tuberculin negativity decreased as the exponential function of age, and the current concept of the annual risk of TB infection was already developed in late 1940s. It was 18.1% in male and 11.6% in female in Tokyo in late 1940s. Based on this concept, age specific TB mortality was analyzed by the type of TB, and the rates of miliary TB and TB meningitis were similar to the rate of newly infected to the total population, while the rate of all forms could be divided into early and late death as shown in Fig. 1. Fourth, I suffered from TB by myself from 1951 to 1953, receiving first thoracoplasty in two stages under local anaesthesia, then right upper lobectomy and segmentectomy of superior segment of right lower lobe. From this experience, I learnt a lot about the psychology and suffering of TB patients. Fifth, the importance of recognition of real magnitude of the problem in such a disease as TB in which many TB cases did not aware of their disease. The answer to this was the first TB prevalence survey in 1953 using stratified random sampling method, and based on the results of the survey, the mass health examination originally focussed on youth was expanded to the total adult population of Japan. Sixth, TB could be reduced rapidly by applying appropriately planned control programme. In big enterprises, the application of intensive case-finding programme brought about the rapid decline of severe TB cases, contributed to the increase of the productivity of the enterprises, thus to the rapid increase of GDP of whole Japan, and the growing spiral between the improvement of health and the economic development was formed by successful TB control. In addition to the mass health examination, BCG vaccination and spread of appropriate treatment in the original TB control law, the registration and case management system and the more extensive application of hospitalization for infectious cases were introduced in early 1960s. Observing the proportion of TB care expenditure to the national medical expenditure, it was 28% in 1954, and it dropped down to 0.4% in recently as shown in Fig. 2. The decline of TB in Japan during 1950s and 1960s was one of fastest in the world. Seventh, there had been marked differences in the prevalence of TB as well as the coverage and quality of TB programmes in several areas of Japan though it was often said that Japan is homogeneous country. To know the real status in various areas of Japan, a chart to express graphically the magnitude of TB and coverage and quality of TB programmes was developed (Fig. 3), and it was finally refined to the current form. Eighth difficulty in changing existing programmes, and we are grateful for kind cooperation of Niigata Prefecture for making several new attempts. Ninth, it has been needed to observe TB problems from global standpoint, and it was actually done through participation to the bilateral cooperation projects on TB control and conducting the international training courses sponsored by JICA. Tenth, TB is a pertinacious disease. As shown in Fig. (ABSTRACT TRUNCATED)