[The incidence of pulmonary tuberculosis in an urban area]

The incidence and prevalence of pulmonary tuberculosis has declined steadily in Japan, but the trends differ greatly by area according to epidemiological status. We studied the incidence and trends of pulmonary tuberculosis in an urban area (population approx. 150,000) during the period of 1979-1988. The area studied is a part of a large commercial city, characterized as having the most prevalent rate of tuberculosis area in that city. Of 1245 newly registered cases, 80% were over 40 years of age. While the incidence rate decreased to 57% in the last 10 years in this area, compared to 69% decrease for all of Japan, it was still considerably higher than the national average. Especially in the 20-59 age group it continued to be 2 times higher than that of the whole of Japan. Moreover, the positive rate of tubercle bacilli at the time of registration had increased remarkably from 27% in 1979 to 62% in 1988. These results suggest the tuberculosis continues to be a significant problem in this urban area, although the steady decline in the incidence of tuberculosis had led to a lack of awareness of this disease.