Studies on the epidemiology of nontuberculous mycobacteriosis in Japan.

The epidemiology of mycobacterial disease in Japan changed considerably over the period 1971 to 1984. During this time, the incidence of pulmonary disease caused by Mycobacterium tuberculosis has steadily declined; disease caused by M. avium complex has remained stable; disease caused by M. kansasii has increased considerably; and, for the first time, substantial numbers of cases caused by M. szulgai, M. fortuitum, M. chelonae, and M. nonchromogenicum have been reported. From 1981 to 1984 the incidence of pulmonary nontuberculous mycobacterioses (NTM) was estimated at 1.73 +/- 0.25 cases per 100,000 population per year; of these, M. avium complex constituted 1.29 +/- 0.24 and M. kansasii 0.34 +/- 0.11 per 100,000 per year. The prevalence of the NTM was relatively high in southwestern Japan (industrialized, warm climate) and low in northern Japan (rural, cold).