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KMID : 0311219800110010001
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Yonsei Reports on Tropical Medicine
1980 Volume.11 No. 1 p.1 ~ p.13
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Environmental Studies of the Snail, Parafossarulus manchouricus, along Yeongsan River in Korea
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Soh, Chin-Thack/蘇鎭琸
Kim, Chong-Whan/Ahn, Yung-Kyum/Chung, Yong/金鍾煥/安泳謙/鄭勇
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Abstract
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Environmental studies on the snail host of Clonorchis sinensis, Parafossarulus manchouricus, along Yeongsan River area in Korea where the Clonorchis sinensis infection is highly endemic, was carried out in 1979.
The area was divided into three parts; upper (U 1, 2), middle (M-1, 2, 3) and down (D-1, 2).
1. The surface sails of the sampling sites were clayish silt in general.
2. Physical and chemical properties such as values of pH, hardness, Cl^(-), KMnO₄ consumption rate, NH₃-N, NO₂-N, NO₃-N, SO₄^(-), SO₃^(-). PO₄^(-3) and Hg showed some seasonal variation but within normal range.
3. Parafossarulus manchouricus remained on the very surface of soil 41.2-71.4% even at 1-8℃.
4. Rediae and cercariae of Clonorchis sinensis were detected in 0.8%, 4 out of 917 examined in January, but failed to find from 2,220 snails collected during spring, summer and autumn.
5. The amount of mercury in soils were 0.159-0.575 μg/gm, but far less amounts in waters and snails.
6. Cercariae of Loxogenes liberum were destroyed in 50 minutes in 20 μg/ml of mercury, and 2 hours 15 minutes in 20 pg/ml of copper. Waters of Pb, Zn, Cr and Cd showed no appreciable cercaricidal effects as far as 6 hours of the observation period.
Overall results suggest that existing environmental conditions in Yeongsan River do not affect the normal ecology of the Parafossarulus manchouricus, the 1st intermediate host of Clonorchis sinensis.
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