らいの減少傾向時に現われる疫学的現象

抄録

The study on leprosy epidemiological phenomenon on the decreasing leprosy prevalence rate has been done by many leprologists before.
A pilot study has been done in the field in Okinawa Island to observe some epidemiological phenomena on the tendency of the decreasing leprosy incidence rate. Okinawa was the most severe leprosy endemic area in Japan and in 1967 leprosy incidence rate was 0.181‰, but recently the situation has been very much improved and the incidence rate became 0.017 ‰ in 1980. Moreover, in Okinawa, leprosy out-patient treatment has been put into operation since 1961 and it has been easy to collect the data on newly-detected patients.
The following results were obtained in the stage when leprosy incidence rate showed decreasing tendency.
1. Leprosy incidence rate, lepromatous incidence rate, child incidence rate and child ratio (under 14 years old) showed decreasing tendency altogether, especially child incidence rate and child ratio were decreasing at a faster pace than leprosy incidence rate.
2. Lepromatous ratio and aged ratio (over 65 years old) were increasing in this stage on the contrary.
3. At this stage the difference between male ratio and female ratio were reducing, especially the difference between both ratio of child patients were reductng at a faster rate than in case of adults.
4. The cross phenomenon in the curve of child ratio and aged ratio was a remarkable sign and the phenomenon previously suggests the decrease of leprosy incidence rate.
5. In this stage the peak of the onset age curve moved from the younger group to the older group.