抄録
There has been a marked decrease in new cases of leprosy from 1903 to today. If the ratio of new cases of leprosy to the total number of patients visiting the Dermatology Department in 1938 taken as 100, the ratio in 1963 is 14. This sharp decrease may be attributed to improvement in hygienic environment, isolation of patients and the widespread practice of giving BCG vaccinations. It is not clear, however, which of these factors has played the major role.
Of the 183 patients treated in the out-patients clinic of the Institute in the past one year, 129 (70%) are home therapy cases and 53 (30%) have been treated in a leprosarium at one time or another. Though 70% of the out-patients are being treated at home without hospitalization, there has been no special increase in new cases of leprosy in the Osaka- Kobe area because of this.
In the Meiji (1903-1911), Taisho (1912-1925) and early Showa (1926-1938) eras, the peak in the age range of new cases of leprosy was at 20-30 years but recently (1950-1963), two peaks, one at 20-30 years (mostly the L-form) and another at 50-60 years (almost all T-form) have become apparent. New cases in the 50-60 year range have, of course, occur- red previously but the number of cases was small compared to the cases in the 20-30 year range and did not form a peak. The extension of the life span with an increase in the number of old aged has also contributed to this. The reason for infection in the aged is not clear but it can be assumed that, similar to childhood, there is a decline in resistance to the leprosy bacillus.
The ratio of new cases of T-form to L-form, which was 7.1: 1 in the Meiji era (1903- 1908) has gradually declined and is 1: 0.9 today. In Japan, the T-form was previously predominant similar to India and Southeast Asia but today, there has been a marked decrease in the T-form but the decrease in the L-form has not been so pronounced.
This increase in new cases in the aged and the reversal in the ratio of T-form to L-form are extremely interesting from the epidemiological viewpoint.
This report was prepared in commemoration of the 35th anniversary of the founding of the Osaka Dermatological Institute.
