Influences of epidemic of Falciparum malaria on the population dynamics of communities and families before the introduction of modern medicine for the prevention and treatment of malaria were evaluated in Yaeyama Islands in Okinawa Prefecture. Population growth and structure in a period (1880-1911) in the Meiji era were compared between 4 hamlets each in the highly infected Iriomote Island (M [Main]-Island) and in the non-infected neighboring peripheral islands (P [Peripheral]-Islands). Although malaria was not endemic in P-Islands, the inhabitants of these islands were also exposed to malaria because they temporarily visited M-Island for cultivating rice and collecting forest resources. Changes of population were examined during two successive periods: period I (1880-1903), during which free moving between hamlets was prohibited by the poll tax law; and period 11 (1903-1911), after the abolition of the law. The results are summarized as follows: 1) The prevalence of malaria in all ages of both sexes was prominently higher in M-Island (26.5%) than in P-Islands (3.4%). The difference in prevalence was prominent among children aged 0-9 years: over 70% in M-Island vs. much less in P-Islands. The prevalence among women in the reproductive age was also higher in M-Island than in P-Islands. 2) Both population and number of households in M-Island hamlets slightly decreased (median was -2.7%o/year in population and -1.2%o/year in households) in period I. This decreasing trend was accelerated in period II (-21%o in population and -13 .5%o in households) by emigration. On the other hand, those in P-Islands highly increased throughout both periods (period I, 16%o increase in population and 18%o in households; period II, 11.8%o in population and 4%o in households). The household members in MIsland hamlets was significantly smaller (median was 3.47 in period I and 3.4 in period II) than in P-Islands (4.75 in period I and 5.74 in period II) in both periods. 3) In period I, when migration was restricted, the ratios of number of children aged under 15 years and of older persons over 50 to the adults aged 15-49 were significantly smaller in M-Island than in P-Islands. 4) The vital statistics in period I were estimated by the West type's stable population model. Crude and infant death rates were significantly higher in M-Island than in PIslands. Life expectancy was also significantly shorter in M-Island. No statistically significant difference in crude birth rate was found between M-Island and P-Islands presumably of a larger variation among the hamlets in M-Island than in P-Islands. 5) These results suggest that the population decrease in M-Island in period I was caused by the high death rate in particular among children due to malaria and related complications. In P-Islands, it is inferred that malaria was only prevalent among men of working age, who engaged in inter-insular cultivation. The low death rate among children and high birth rate in P-Islands are attributable to this communal preventive behavior system against malaria. This probably contributed to the high population growth rate. For the malaria control measures of the day, further efforts should be paid to the evaluation of preventive behavior system focused on children and mothers.
Physical health levels of 95 married couples (group A), who live in the suburbs of big city, and 202 married couples (group B), who live in a local city of Kanto district, were measured using a health questionnaire, the Todai Health Index (THI). The male subject of both groups are workers of private company and the average age is early forties. This research was focused on the effect of smoking and place of residence on subjective complaints. Mean values of scale scores of couples' respiratory symptoms and husbands' digestive symptoms of group A were statistically higher than those of group B by the two-way analysis of variance. But no difference was recognized by the degree of smoking. Interactions existed on the effect of smoking and place of residence on the mean values of scale scores of wives' respiratory and digestive symptoms. These results indicate that respiratory symptoms and husbands' digestive symptoms increase by the modernization, but the effect of smoking habit on respiratory and digestive symptoms were relatively small.
The rates of moving out (out-migration) and of response to self-administrated questionnaire on respiratory symptoms were surveyed about 3600 inhabitants, who had participated in the first one during their school childhood, living in the town located in rural district of Hokuriku area. Out of the cohort of junior high schoolchildren at the 1st grade at the first survey 53.4% of male and 26.5% of female lived in the same town at 20th years survey when their age was 30-31 years old. The former was significantly higher than the latter (p<0.01). The rate was significantly higher of the male inhabitants in the agricultural district (64.4%) of the town compared with in the downtown district (47.4%), (p<0.01). The response rate to the 20th year survey, related neither to gender nor age, but related to the district. It was 87.6% in the agricultural district and 76.6% in the downtown. Significant difference was observed (p<0.05) between the percentages. Due to moving out and non-response to the questionnaire, participation in the 20th year survey were 40s% out of primary schoolchildren in the 1st grade, and 50s% of male out of the junior high schoolchildren and 20s% of female out of the primary schoolchildren in 1st grade. Considerable number of schoolchildren moves out of the original living districts until the age of their adolescent because of entering into higher schools, getting jobs, getting into marriage and so on. It is important for the cohort survey to prepare some devices to maintain a higher response rate involving the out migrants.
The mortality rates and causes of death among elderly people aged sixty five and over were compared between China and Japan. The data used for comparison was China's 1990 and Japan's 1990 vital statistics. It appears that the mortality rate in China was higher than Japan. Comparing the causes of death, it was found that the death rates involving cerebrovascular diseases, malignant neoplasms and heart diseases in urban districts of China was higher than those in Japan. Also the death rate of people with bronchitis in rural districts was significantly higher in China than Japan. Comparing the death rates resulting from malignant neoplasms by each organ, the death rates of lung cancer and esophageal cancer were higher in China than Japan. With regard to heart diseases, the urban district death rate of ischemic heart disease was higher in China than Japan. The differences in the medical systems and life styles in China and Japan were suspected as the reasons for the differences of death rates and causes of death in China and Japan. Further study will be needed to clarify the reasons.