This study was performed to observe the recent infection status of Sesarma dehaani with the metacercariae of P. iloktsuenensis in the well-known enzootic focus, Sumjin river delta. A total of 74 Sesarma dehaani were collected from a focus near the mouth of the Sumjin river in November, 1986 and February, 1987. The crabs were examined for P. iloktsuenensis metacercariae by the method of Seo and Kwak(1972). The metacercariae of P. iloktsuenensis were found in the liver of the crabs. Among the 74 crabs examined, 47(63.5%) were found infected with 1-102 metacercariae (18.2 per crab). The infection rate and metacercarial density increased as the size of the crab was increased. From the results, it is suggested that the life cycle of P. iloktsuenensis is actively maintained in the Sumjin river basin.
