In an attempt to determine the recent patterns of population density of the crayfish, Cambaroides similis, and infestation of the crayfish with the metacercaria of Paragonimus westermani in Kyungpook Province, Korea, the crayfish collected in the six endemic areas, Kum-ge, Wha-cheon, Sang-seon, Ju-dong, Ok-bun dong, and Sang-weon dong streams were examined from April, 1981 to September, 1982. The results obtained in 1982 were compared with the data derived from the crayfish collected at the same streams by Park and Choi(1974).
The population density of crayfish in the six endemic areas of P. westermani in the present study decreased markedly compared with those in 1974.
The infestation rate for the metacercaria of P. westermani in the crayfish examined and the intensity of infestation in the positive crayfish also decreased compared with those reported by Park and Choi(1974). In the 1974 survey, the metacercaria was found in all parts of the crayfish whereas it was found only in the cephalothorax, the gills, and the liver in the present suevey. In the average number of metacercariae perpositive crayfish (M.P.P.C), a pronounced reduction was encountered in all endemic areas between 1974 and 1982. The number of infested crayfish and the metacercaria of P. westermani in infested crayfish in 1982 was so small that it was impossible to analyze the relationship between the number of metacercaria and the length of crayfish and to compare the data between 1974 and 1982. It was found in the present study that the population density of crayfish in the endemic areas and the infestation of the crayfish with the metacercaria of P. westermani has decreased drastically over the eight-year period from 1974 to 1982.
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