[Tuberculosis among immigrants in Japan--epidemiological, clinical and sociological features, and the future of control].

Case of tuberculosis among immigrants in Japan have been increasing recently as the entry of the foreigners increases. The 1993 national survey showed that the number of the newly registered tuberculosis patients among immigrants (new comers) was 593 (1.2% of total patients) in 1992. Though their proportion among all patients is still yet small, immigrant cases show remarkable disparity in geographical and age distribution. Immigrant patients present various challenges in the control of tuberculosis, with higher rates of defaulter in treatment and drug resistance. This study analysed the characteristics of the problems with various data and made recommendations for the future control programme. Epidemiologically, the mean tuberculosis incidence during the period from 1987 to 1992 was estimated for the population of each country of origin. The rate for the whole immigrants was between 58.1 and 76.7 per 100,000, which was 2 to 5 times of the rate (i.e. 39) for Japan in 1992. The trend of the incidence after the arrival in Japan by year cohort was also estimated. It was found that the shorter the stay, the higher the incidence. Future estimate of tuberculosis incidence in immigrants was made based on the assumptions of the population in and out flows. In 2005, the number of new immigrant patients will be between 1169 and 846, representing 3.4% to 2.5% of all tuberculosis patients expected a decade hence. By reviewing the clinical data and chest radiogrphy of 157 immigrant patients currently diagnosed in Tokyo area, the attack timing of the disease for each patient was estimated. Nearly half the patients who would be diagnosed later was estimated to have some abnormal shadows on chest radiography before arrival in Japan, while the other half or at least 30% developed tuberculosis after arrival. These indicate the importance and the limitations of screening by chest radiography at the early stage of arrival. The clinical status and treatment compliance were better among the legal immigrants such as Japanese language school students that the over-stay (illegal) immigrants. The extra-pulmonary cases consisted only 7% of the total disease, which was similar to the whole patients in Japan. The perception and knowledge about tuberculosis and tuberculosis services among immigrants was found some different from those among Japanese. With the data analysed above and the information on the policy and guidelines in other countries, it is recommended that guidelines for improved Case-finding and treatment of tuberculosis among immigrants need to be developed in Japan, and pilot trials at local level should be instituted. For surveillance for tuberculosis in immigrants a standardized information system must be developed.