The present studies were undertaken to determine accurate1y whether Korean native fresh-water shrimps can serve as the second intermediate host of Clonorchis sinensis. The experimental results obtained were as follows;
1. Metacercaria of Clonorchis sinensis was not discovered in 36 Macrobranchium nipponensis (De Hann), 1992 Palaemon paucidens (De Hann) and Palaemon modestus Heller, and 860 Caridina leucostica Stimpson, collected in Kimhae district, which were digested in artificial gastric juice, using binocular dissecting microscope.
2. Cercariae of the Chinese liver fluke could not approach the body wall of young shrimps due to streaming caused by their motion.
3. Young Palaemon spp of 247 were divided into two groups and placed in two different room aquariums, one is at high temperature, the other is normal. Then they were contaoted with the cercariae. Only 11 degenerated metacercariae were found in 9 Palaemon spp. It was suggested that they had died immediately or within a few days after penetration. Furthermore the temperature did not affect the infective ratio.
4. At the field experimental aquarium, no metacercaria of Clonorchis sinensis was discovered in 100 Palaemon spp. which had been brought into contact with 5000 Parafossarulus manchouricus two trials.
5. Specific changes in the cercariae mixed with the extract of shrimps meat were not observed through the dissecting microscope.
7. These results suggest that the Korean native shrimps cannot serve as the intermediate host of Clonorchis sinensis.
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