The author has undertaken to grasp the actual conditions in which fishing industry is carried out on the southern coasts of Hokkaido, and tried to consider various problems involved therein from hygienic point of view. It was to elucidate the special features of fishing industry and various weak points to be improved in that connection, in terms of medical or hygienic knowledge, for the purpose of obtaining such data and materials as would contribute to the increase of production, rationalization of management, and decrease of disease incidence, deaths and accidents, in other words to the prosperity of fishing industry in that area. The contents of this study are as follows: Part 1. Introduction Part 2. Living Expenses Part 3. Time-study and Determination of Energy Requirement Part 4. Nutrition.
In the north-eastern part of Japan incidence of hypertention is very high among farmers, and their death rate from cerebral hemorrhage is also high, though their daily intake of fat is estimated at some 5 to 10% of their total caloric intake. The author studied the serum lipoprotein by the electrophoretic method with a view to contributing to the solution of the problem of lipid-metabolism of farmers. As a result, it was found that, β-lipoprotein:α-lipoprotein was high in the hypertensive group and that it was correlated with the concentration of serum cholesterol, though their mean values appeared to be low as compared with those of the patients of hypertensive or coronary diseases in other districts.
In Ichihara-gun, Chiba Prefecture, a rural district, two villages where no anti-hookworm measure had hitherto been taken were selected for the study. The inhabitants of these two villages were first given mass anthelmintic treatment twice, but after that no more anti-hookworm measure was taken. In such natural conditions, theconditions of newand re-infection were observed for more than one year's time byway of stool examination. 1. The hookworm egg-positive rates: 82.4% for Itohisa, Miwa-machi, and 41.2% for Nakano, Shitsu-mura. Both species were present, but Necator americanus predominated in either of the two areas. 2. The cumulative rates of new-and re-infection for the whole year: It was higher in Itohisa (36.9%) than in Nakano (8.4%). But, in the two other villages where antihookworm measures had been executed over a long period of time, such rate was extremely low. 3. The seasonal fluctuations of the rates of new-and re-infection: In both of these subject villages it was higher in the warmer season including the wet season, i. e. mid-April to mid-July. 4. Analysis of the rates of new-and re-infection by modesof living: In Itohisa, school children showed a higher rate of new-infection, and the adults of the same area presented the higher rates of both new-infection andre-infection.In Nakano, no significant difference was seen between school children and adults, but one thing to be noted is that the cases of conversion to positive among school children were all of them new-infection cases. 5. New-and re-infection rates by sex: No particular difference was recognized in either of the two areas. 6. Classification of new-and re-infection cases by species: In bothof the villages, majority of the cases carried Necator americanus only.
During the period from July, 1957, to September, 1958, epidemiological studies were carried out, with the specific object of investigating familial prevalence, on Ascaris and hookworm infection among the inhabitants of 10 agricultural communities and 1 residential area (the control) in and around Chiba City. The rural areas where the investigation was carried out had been so selected that they included lands with different geographical features-the reclaimed land, the land where paddy-fields predominte, and the land where fields prodominate. With over 90 per cent of the inhabitants participating in the program, tests for infection with Ascarides and hookworms were conducted by means of smear method, suspension method and culture method. 1. The smear method proved superior to the suspension method in detecting unfertilized Ascaris eggs, whereas the culture method was better than the suspension method in detecting hookworm eggs. 2. Farmers and part-time farmers had a higher incidence of positive reactions to tests for Ascaris and hookworm infection than did non-farmers. The farmers cultivating fields ranging in area from 0.1 to 2.0 tan (1 tan corresponds to 0.245 acre) had the highest rate of Ascaris infection.Hookworm infection had no relation to the area of land cultivated. Both Ascaris and hookworm infection rates were low among the farmers using night soils fertilizer by mixing it with manure, than among the farmers employing other methods of night soil disposal. 3. Among adults, those who were engaged in agriculture had the highest incidence of both Ascaris and hookworm infection. Among those engaged in agriculture, males had a higher incidence of infection with Ancylostoma duodenale, and females with Ascarides and Necator americanus. 4. A. duodenale' showed the highest familial prevalence, followed by Ascarides and N. americanus in the indicated order. The prevalence of A. duodenale and N.americanus among those members of the family who were engaged in agriculture was as high as the familial prevalence, but the prevalence of Ascarides among those members of the family who were engaged in agriculture was lower than familial prevalence. Familial infection of these parasite worms in terms of the relations between husband and wife and parent and child gave the following picture: husband had a close relation with wife in infection with Ascarides; parent and husband had a close relation with child and wife, respectively, in infection with A. duodenale; and husband had a close relation with wife in infection with N.americanus. 5. The following picture of mixed infection was obtained: Ascarides were closely related to A. duodenale in infecting children; Ascarides and A. duodenale were closely related to A. duodenale and N. americanus, respectively, in infecting adults. No close relation was found between Ascarides and N. americanus. 6. In the light of the result of present investigation, it would seem that A. duodenale has larger possibilities of invading the human body by mouth than N. americanus.
With a view to elucidating some aspects of round-worm infection and mass anthelmintic treatment in rural area, the author conducted an investigation of all the pupils of elementary and lower secondary schools in Shirahama-machi, Chiba Prefecture (5 schools, 2, 180 pupils). Monthly stool examination was carried out from Feb. 1957 to Mar. 1959, together with more than ten times of mass anthelmintic treatment in between. Thus, such facts as transition of positive reaction rates, speed of infection or how soon infection occurred, infection rates by seasons, relationship between consecutive anthelmintic treatment and rate of conversion to negative, and that between the frequency of treatment received and the cumulative rate of conversion to negative were obtained by schools. The results of study are as follows. 1. Althouge all the five schools belong to the same local administrative unit, machi, their initial positive rates showed a considerable variance, the highest rate being 58.5% and the lowest 12.5%. 2. The infection speed by schools was high for the groups with high initial positive rates, in regard to both new- and re-infection. The cumulative positive rates by schools at the end of the first year ranged between 63% and 26%. The infection speed for the re-infection cases showed a higher value than that for the new infection cases. 3. Infection rates by seasons inclined to be lower in June and January, and higher in November and February to May inclusive. 4. Both Macnin and Nemacin, when employed repeatedly in consecutive treatment, appeared to cause a gradual decline in the rate of conversion to negative;and the severer the degree of infection, the more difficult it was to attain conversion to negative, it seemed. 5. The cumulative rates of conversion to negative obtained were: 78.6-94.3% by two courses of anthelmintic treatment, and 94.7-100% by four courses. 6. As for the transition of positive reaction rates, the rates became lower in the second year as compared with the first year of anthelmintic treatment program. However, in spite of the consecutive treatment given almost monthly, it would not fall beyond a certain level but rather showed a kind of side crawls (5-15% on an average). On the basis of the above-mentioned findings it was concluded that, taking into consideration the infection speed, treatment should be give more frequently to the groups with high initial positive rates and to the reinfection groups, although it is generally said that mass treatment should be given 2 or 3 times a year. Furthermore, it was considered that it would be difficult to attain the objective of the extermination of round-worms only by means of mass anthelmintic treatment, and that the treatment should be executed side by side with such measures for preventing reinfection as hygienic education, environmental improvement, and esp. the hygienic disposal of human waste, etc.
This is a clinical study conducted with a view to determining the effect of Vitamin A on the prevention of Ascaris re-infection. 692 school children were used as subjects of study. A strict preliminary examination was conducted from February to October, 1957, as a result of which 110 children were deliberately selected. Such 110 children were divided into two groups at random, one of which was given V. A.(10, 000 IU per capita daily) for a whole year, and the other served as a control group. Thus, during the period of V. A. administration and during the 9 months' follow-up period succeeding it, the occurrence of re-infection was closely observed for comparative study. A. Preliminary examination 1) The cumulative rate of re-infection among school children during 6 months' time was 42.0%. 2) All the egg-positive children were subjected to mass anthelmintic treatment in February and in June. And, from among those whose conversion to negative was confirmed by the August stool examination, but who had previously been positive both in May and in June and also positive from February to April consecutively or who had become negative as a result of treament executed in February but had been infected again thereafter, 110 children were finally chosen at random for the purpose of this experiment. These 110 persons were divided at random into two groups;then it came out that they were of practically holomogous composition as to the sex distribution ratio and the severity of infection (number of eggs detected). 3) For caution's sake, these subjects were again given two courses of anthelmintic treatment before the experimental administration of V. A, i. e. in September and in October, so that the possible inclusion of such cases as those who had larvae circulating within one or other organ unnoticed or of false negative cases be eliminated. B. Results of experimental V. A. administration and follow-up results 1) Re-infection rate during the period of V. A. administration: The rate of the V. A. administered group was markedly lower than that of the control group. 2) Transition of the cumulative re-infection rate: After 5 months of the commencement of the V. A. administration, marked difference was observed in the ascending rates of the two groups. At the termination of the V. A. admintration, the V. A. administered group showed 29.1% while the control group reached to 60.0%-significant difference was obtained between the two values. 3) Relationship between the severity of infection prior to treatment and the severity of re-infection that took place during the V. A. administration: No definite relationship was recognized. 4) Severer re-infection occurred more frequently in the control group. 5) Spontaneous conversion to negative during the V. A. administration period: No significant difference was seen between the two groups. 6) Transition of the cumulative rate of re-infection during the follow-up period: The two groups presented no particular difference. Rise of the re-infection rate in V. A. administered group was ascribed to the lack of long lasting effect of V. A. 7) No side effect was recognized in the administration of V. A. It is concluded that V. A. is effective in preventing round-worm re-infection, but its effect appeared not long lasting.