[Tuberculosis and its control--lessons from the past and future prospect].

Koch R reported the discovery of tubercle bacilli on March 24, 1882, and the numbers of death from phthisis were collected in the vital statistics from the latter half of 1883 in Japan. Tuberculosis death was officially adopted in the Japanese vital statistics from 1899, and there was certain disagreement existed between the numbers of death from TB and phthisis in 1899, the analysis on the trend of TB in Japan was done based on TB death. Trend of TB in Japan in the past 100 years could be divided into five phases. In phase 1 (1899-1918), TB mortality had increased with the first industrialization of Japan with main focus on the weaving industry. During this period, TB mortality of female was higher than that of male and then major victims of TB were young girls born from 1890 to 1925. In phase 2 (1918-1930), TB mortality decreased through excess death of TB cases by the influenza pandemic in 1918. This decline due to influenza pandemic was seen all over the world, and in the European countries and the U.S., the decline continued up to 1945 while in Japan, TB had increased again in the phase 3 (1930-1945) mainly due to second industrialization with main focus on heavy industry and the impact of quasi-war and war conditions. In phase 4 (1945-mid 1970s), TB started to decline fast due to the excess death of TB cases during the World War II and then, the application of modern TB control started from early 1950s. In phase 5 (from mid 1970s until now), decline of TB has showed down. Increase or slowdown of TB decline was seen nearly all countries of the world, however, its causes were different from country to country. In case of Japan, slowdown was caused by the rapid ageing of the population, in developing countries mainly by the impact of HIV epidemic and in industrialized countries, mainly by the migration of the population and partly by the HIV epidemic. Contribution of phthisiology in Japan to the global progress of phthisiology could be summarized as follows: elucidation of the pathogenesis of TB when TB was highly prevalent in Japan by high incidence of TB from primarily infected youth, the development of mass screening for TB using radiophotography technique developed in Japan, completion of the interpretation method of chest X-ray findings, first success in the mass production of freeze-dried BCG vaccine in the world, the first implementation of the TB prevalence survey using random sampling method in 1953, and the development of a new drug for TB, kanamycin. Phthisiology also contributed to the progress of international health. As the objective index to measure the magnitude of TB problem, the concept of annual risk of TB infection (ARTI) was introduced by Sutherland and Styblo, and by using ARTI, the epidemiological situation of TB could be divided into 3 categories; high prevalence country with ARTI above 1%, low prevalence country below 0.05-0.1%, and middle prevalence country inbetween. To reduce the burden of TB in high prevalence countries, so-called DOTS strategy of TB control was introduced and has been applied in most developing countries, and the gap between high and low prevalence countries has reduced in the past decade. Cooperation in global TB control has also been done actively from the government and NGOs of industrialized countries under the strong leadership of WHO. For the success of TB control, the transmission of tubercle bacilli in a community should be cut either infection, onset of TB or the progress of TB. Prevention of TB infection could be achieved by the early detection of TB cases and their cure by the treatment. To encourage early visit to doctors for those with symptoms suggesting TB and adequate examinations at medical institutions for these persons would be a major tool of early detection of TB cases in Japan in the future. In addition, there is no doubt to intensify contacts examinations and source investigations. It is hoped to elucidate recent pathogenesis of TB by applying new technologies such as QFT and RFLP. Prevention of onset of TB will be focused on the preventive use of TB drugs, however, development of new vaccine better than BCG is also encouraged for the developing countries where the risk of TB infection is remained high. TB is now a curable disease, and the duration of treatment has been shortened to 6 months. If new more potent TB drugs were developed, and the total duration of treatment could be shortened, the global TB control could be done much more easily, and also most MDRTB cases could be cured. Otsuka Pharmaceutical Company is now developing a new potent drug which has no cross resistance with existing TB drugs. This new drug is now on the clinical trial phase II, and it is hoped that Japan can make another great contribution to the global TB control. It is my sincere wish that the government continues to assist the research to develop new TB drugs and new technologies used in TB control, and in future, if it is needed to change the current policy of TB control, a new policy should be tried in a pilot area before its introduction on national level. The Japanese Society for TB is a key organization in developing further research and the training of new personnel engaging in TB research and control, and I sincerely hope further development of the Society.