[Commemorative lecture of receiving Imamura Memorial Prize. III. Estimating the year of eradication of tuberculosis in Japan].

The year by which tuberculosis could be eradicated, has been discussed for several foreign countries, and based on those results, new strategic plans and goals have been elaborated. Therefore, in Japan too, it was desired to estimate the point at which eradication of tuberculosis would be achieved. The author estimated the year of eradication of tuberculosis, according to the criterion proposed by Dr. Styblo that "tuberculosis is eradicated when the prevalence of tuberculosis infection in the general population has fallen below 1% and continues to decrease". If the risk of infection is changing at a regular rate, it is possible to estimate the risk of infection at any particular time. Once the risk of infection is determined, it is also possible to calculate the age-specific prevalence of infection and the proportion of the population infected with tubercle bacilli at any given time. In Japan, the risk of infection before World War II was assumed to be around 4%; since then, it has declined on average, by 10 to 11% annually. The incidence rate in Japan also has declined, on average, by 10 to 11% annually. However, since late 1970s, the annual speed of decline of the incidence rate has slowed down. Therefore, I assumed that the recent trend of the infection risk is the same as the trend of the recent incidence rate among the 0-29 year age-group. The size of the effect of age on the risk of infection has been discussed. The author also considered age-effects in the model.(ABSTRACT TRUNCATED AT 250 WORDS)