[The epidemiological study on leprosy in the Ryukyu Island. The 2nd report: On the geographical status (author's transl)].

Recently the epidemiological improvement on leprosy disease in the Ryukyu Island has been observed. Leprosy Prevalence Rate (P. R.) and Leprosy Incidence Rate (I. R.) in the Island in 1970 were 1.97‰ and 0.088‰, but on the other hand the P. R. and the I. R. were 1.34‰ and 0.059‰ in 1975. So generally the leprosy epidemiological status in the Island has improved after the reversion of the Island to Japan in 1972. The drift of population to the urban areas from the rural areas has taken place from 1971, especially after the reversion. The rural areas (Miyako Islands, Yaeyama Islands and other Islands in Okinawa) have been sparsely populated and the urban araeas (Naha City, Urazoe City and their outskirts) have been rapidly grown in population.According to the drift of population, the geographical status on leprosy endemic in the Island has something been changed after 1971. In regard to leprosy onset place, the following change can be observed: in the Naha City (one of the urban areas) the total number of newly-detected patients was only 5 (I. R. 0.017‰) in 1969 but in 1974 was 20 (I. R. 0.065‰). On the other hand in Miyako Islands (one of the rural areas) the number was 38 (I. R. 0.552‰) in 1969 and in 1974 was 17 (I. R. 0.293‰).The another statistics shows as follows: The ratio of the annual newly detected patients in Naha City to total number all the Ryukyu Island was 5.2% in 1969 and 28.2% in 1974. But the ratio in Yaeyama Islands was 21.6% in 1969 and only 7% in 1974.So before the reversion, the endemic pattern on leprosy disease was as follows: Leprosy infection and onset have occured in the same place in the rural areas. But after the reversion, the pattern was changed as follows: Leprosy infection has occured in the rural areas and the disease developed in the urban areas.The phenomenon of the change on leprosy onset place in the Ryukyu Island after the reversion seems to be caused by the movement of population, by social developement in the rural areas and also by the improvement of leprosy endemic status in the Islands.From the fact described above, it may be concluded that leprosy control programs in the urban areas in the Island should be more emphasized in the furture.