One is inclined to imagine that the incidence of respiratory diseases will be negligible among rural people who live and work in fresh and clean air. On the contrary, however, we have reports on the high incidence of chronic obstructive pulmonary diseases and on the existence of a variety of specific respiratory diseases which are incidental to farm work. To clarify this situation, the Japanese Association of Rural Medicine organized a special study group and carried out various studies with grants from the Ministry of Health and Welfare. This is the study group's summary report of the four year research project prepared in conclusion of the project. The actual state of respiratory diseases among rural people, as investigated by the present study group, can be summarized as follows: 1) In rural districts, in spite of its freedom air-pollution, there exist in high percentages people suffering from respiratory symptoms and patients of obstructive pulmonary diseases. As the important cause of this phenomenon, farm operations, especially thrashing, rice-hulling, compost preparation, scattering of agricultural chemicals can bementioned, which invite the development of symptoms and their aggravation. 2) Pathologically, farmer's pneumoconiosis attributable to farm operation dust was evidenced, crying for the necessity of dust prevention measure during farm operations. 3) In connection with atopic asthma the study group proved the antigenicity of rice-straw, wheat-straw, celiae of tea-sprout, young leaves, and chrysanthemum leaves. There are also anumber of already known antigens. It is necessary to establish measures for its prevention and treatment. 4) In rural districts of Japan, esp. in stock-raising farm houses, there are in comparatively high percentages those who react positive to fungous antigens which are the causes of farmer's lung. However, there have hitherto been reported only two cases, and the study group added one more. In the future, more extensive practice of immunological tests and clinical follow-ups of the positive cases will be necessary. 5) In view of the results reported above, it is considered that there are numerous questions concerning respiratory troubles and diseases in rural districts which are awaiting further study.
Of all types of farm work in Japan, the threshing of rice, in which dust is generated in large quantities, produces the worst influence on the respiratory organ, and the author termed this symptom “thresher's bronchitis.” The repetition of thresher's bronchitis gives rise to chronic bronchitis. There have been the autposy cases of elderly farmers who suffered from pneumoconiosis, as he had been exposed to dustin over 30 years of threshing work. The symptom might well be called “thresher's pneumoconiosis.”
From our survey of respiratory diseases in rural district, we concluded as follows: 1). Prevalence of positive antibody fiter to Thermophilic actinomyces in farmers of one village was 19.4%. 2). Alternaria is one of the most important mold antigen to asthma in rural area. Specific IgE antibody to Alternaria was identified in sera of many patients suffering from asthmatic attack in summer season. 3). Pollinosis in Nagano Prefecture a). A check of patients by age reveals that the incidence is high among people at ages 20-40. b). A check of the distrbution of patients by month indicates that the incidences are concentrated during the period of March through October, and this period is classifiable into three seasons-spring tree season, summer grass season and autumn weed season. c). According to our survey on atomospheric pollen, Japanese cedar, alder, Japanese birch, zercova, walnut, oak family and white mulberry were found in tree season, meadow foxtail, orchard grass, timothy andrice in grass season and ragweed, common mugwort, chrysanthemum, Japanese hop and smooth pigweed in weed season. Of all hayfever plants, Japanese cedar, orchard grass and common mugwort have high antigenicity. d). We discussed the findings of the survey we have performed on a number of cases of six pollinosis-Japanese birch, walnut, apple, orchard grass, ragweed and common mugwort.
In the previous study, relatively high prevalence of asthma-like attacks associated with handling rushes was observed. In this connection, mass survey of the intradermal skin test (×10000, 0.02ml) by the extracts of rush (Juncus effusus L. var decipiens Buch. forma utilis Makino) and the dusts in the weaving room containing rushes, dyeing materials (sendo) and other house dusts was conducted for the rush farmers (65 males, 143 females), other farmers (21 males, 91 females) and women without farming (28 females). The results were summerized as follows. 1) The positive rates in skin test were estimated to be 7.7% for males and 2.1% for females of the rush farmers by the extracts of rush, and 23.1% for males, 10.5% for females by the extracts of dusts in the weaving room. On the centrally, 4.8% for males, 1.1% for females of the controlled farmers by the former extracts, and 19.0% for males, 8.8% for females by the latter extracts. And among females without farmiing, 0% and 3.6%, were positive respectively. 2) The positive rates were not associated with age, respiratory symptoms and past history of asthmalike anfall. The rush farmers were observed relatively higher percentages of positive reaction than the controlled groups, but not signifficantlly. 3) The results do not clarify the causative agent of antigen-antibody reaction to the asthmatic anfall among the rush farmers, but suggest that peoples, whether farmer or not farmer, may be sensitized by the rush antigen through the farm works and or using tatami mat and other rush products in daily life.
One hundred and thirty one city inhabitants, have been lived in Kumamoto city over 20 years, were examined by gel diffusion test for precipitins to 12 antigens of fungi and 2 pigeon proteins. And the prevalence of positive reactions to these antigens was compared with the former research for the farmers in mountain district in last year. The results were summerized as follows. Fifteen positive sera of 131 tested (11.5%) were detected to c. acremonium. And, 6.7% to candida, 6.1% to s. granarius, 5.9% to p. pullulans, 3.8% to t. vulgaris, 1.5% to m. faeni and positive to other 7 antigens tested. Thirty seven cases (28.2%) were positive to at least one antigen of all 14 tested. The proportion of positive selological tests in city inhabitants was rather higher than that of the farmers. The results suggest that the city inhabitants in Kumamoto prefecture have been exposed relatively high amount and/ or various kinds of fungi antigens as well as farmer's case.