An epidemiological survey conducted from March 1977 to October 1978, revealed that in the river Taeka running through Seong-ju county, Kyungpook Province, one habitat of the snail, Parafossarulus manchouricus, was found. The snail population in the habitat was very low, and no Clonorchis sinensis cercaria was found in the snails examined. Seven species of fresh-water fish caught were examined for the presence of the metacercaria of Clonorchis sinensis. Of these, 3 species of fish, the Korean shiner, Gnathopogon atromaculatus, the gudgeon, Pseudogobio esocinus, and the striped shiner, Pungtungia herzi harbored the encysted larvae. The rate and intensity of infection with the metacercaria in the fish was, on the whole, low. The prevalence of Clonorchis sinensis among the residents in Seong-ju county was also low. The overall infection rate for the fluke in 1,012 residents was found to be 13.4 per cent. The infection rate for Clonorchis sinensis in males and females was 17.1 and 9.2 per cent, respectively. This difference was statistically significant ( t > 2). It is found that Clonorchis sinensis is less prevalent in Seong-ju county than in the other counties of Kyungpook Province, Korea.
