Recent papers suggested that as the result of the increase of Japanese travellers abroad, number of patients affected with imported tropical disease increased every year. This fact also implies that foreign visitors are bringing tropical disease into Japan. Therefore, we have conducted a survey of foreign visitors who visited Matsushita Electric Co. Ltd. for the purpose of technical training for short periods from 1972 to 1976, studying the possibility of invasion of tropical diseases by interview and on medical records. The results obtained were as follows :
1. Of total 532 visitors, 485 were from tropical regions and 47 from other countries, and the morbidity rates indicated 20.2 per cent and 29.8 per cent respectively in the observation period of one month following their arrival.
2. Fortunately no tropical diseases such as malaria, filariasis, dengue fever and cholera were found so far.
3. Two cases, a Malaysian with Tenia saginata and an Iranian with orchitis following mumps which had affected him for some time before their arrival, were cured.
4. Many visitors from tropical regions were easily affected with common cold within a few days after their arrival, especially in the fall and winter season, as compared with those from Europe and North America.
5. A thorough check-up routine of the Japanese returnees and foreign visitors to Japan and general practitioners' good understanding of the imported tropical diseases are mandatory for the prevention of tropical diseases in the future.

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Primaquine was given to 110 Japanese malaria patients 132 times for the eradication of P. falciparum gametocytes or for the treatment of relapsing malarias.
1) Primaquine was tolerated well by the patients despite minor gastrointestinal discomforts. No hemolytic anemia developed reflecting the extreme rarity of G-6-PD deficiency among the Japanese.
2) The exact failure rate of radical treatment of vivax malaria was not obtained as many patients returned to malaria endemic areas to continue their work. There were two patients each from PapuaNew Guinea and Kalimantan and one case from India who relapsed after one course of therapy. Two patients from Kalimantan and one patient from Papua-New Guinea were radically cured by the second course of primaquine treatment. Another case from Papua-New Guinea was reinfected in the same area and another case from India is free from malaria for 6 months after the second primaquine treatment.
Three patients relapsed after two successive courses of primaquine treatment at an interval of two to three months and were radically cured by 30 mg of primaquine given over seven days.
3) All the six ovale malaria patients were radically cured by one course of primaquine treatment.
4) P. falciparum gametocytes were sensitive to primaquine irrespective of the chloroquine-resistance of the asexual form of the parasites. There was indication that the response to primaquine in the second treatment was a little slower than in the first treatment.
The gametocytes in the untreated with primaquine patients, after they reached a peak level, decreased logarithmically and their trend was expressed as logy=-ax+b, where x is the day after treatment with schizontocidal drug, y the parasite count per μl of blood, and a and b constants. The equations in two patients were as follows. logy= -0.1366x + 4.3870 and logy= -0.0869x+ 3.6497.

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1) Morphological observations were made on 21 cholera patients who were autopsied soon after death. Since 19 of the cases were those dying within 41 hours after the onset, the changes with time in the early stage of cholera were studied.
2) Small intestinal mucosal abnormalities are represented by acute inflammatory reactions and subsequent atrophic alteration of villous architecture. In these changes, the increased reproduction of epithelial cells in crypts by inflammatory stimulus seems to play an important role.
3) Increased secretion of excretory glands was seen in goblet cells of the small and large intestines, in Paneth's cells of the intestine, and in goblet cells of the bronchi in cases of aspiration of gastric content. Increased secretion of pancreatic juice and bile was also observed.
4) It is speculated that cholera toxin is absorbed by the intestine or some stimulating substance is produced in the intestine. This is suggested by a) reactions of the mesenteric lymphnodes and spleen, b) fatty changes of the liver and kidney, and c) increased secretion of pancreatic exocrine system.
5) The death may be attributed to cardiac failure and swelling of the brain resulting from dehydration. Respiratory disturbance due to aspiration of gastric content should also be considered. Renal changes in the early stage of the disease are mild and consequent renal failure could have been prevented by proper transfusion.

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