Cipangopaludina chinensis malleata (Gastropoda : Viviparidae): A new second molluscan intermediate host of a human intestinal fluke Echinostoma cinetorchis (Trematoda : Echinostomatidae) in Korea

Two species of the viviparid snails have been reported in Korea, e.g., Cipa ngopaludina chinensis malleata and Cipangopaludina japonica. Cipangopaludin a chinensis malleata collected at 3 of 12 localities were found to be infec ted with metacercariae of Echinostoma cinetorchis, one of the snail-borne h uman intestinal trematodes in Korea. Metacercariae from these snails were f ed to rats (S/D strain), and adult worms of E. cinetorchis, characterized b y 37-38 collar spines on the head crown, were recovered from the ileocecal regions. However, no C. japonica collected from 2 localities harbored the m etacercariae. In experiments with laboratory-bred viviparid snails, all viv iparids were not susceptible to miracidia of E. cinetorchis. To confirm the identity of second intermediate hosts of E. cinetorchis experimentally, 2 species of viviparid snails were exposed to the cercariae from Segmentina h emisphaerula that had been infected with miracidia of E. cinetorchis. Both species of snails were susceptible to cercariae of E. cinetorchis. This is the first report of Cipangopaludina spp. serving as the second intermediate host of E. cinetorchis and as a potential source of human infection.