Experimental establishment of life cycle of Clonorchis sinensis.

Objective To establish and maintain the life cycle of Clonorchis sinensis in laboratory.Methods Adult worms and eggs of Clonorchis sinensis were collected from naturally infected cats.Eggs were ingested by freshwater snails in aquarium.When the cercariae were released from infected snails, they invaded into freshwater fishes.From the 30th day on after the release of cercariae, the infection rate and metacercariae density in freshwater fishes were determined.Results After 95 days the infected snails began shedding cercariae in a temperature range of 24.3-37.2 ℃, and no cercariae were found under 20 ℃.The infection rate in the snails Parafossarulus striatulus and Alocinma longicornis was 12.5% and 18.0%, respectively.Metacercariae were found in fish at 30 days after cercariae infection, and matured metacercariae were detected in 45 days.The number of metacercariae per gram of fish meat in Pseudorasbora parva, Ctenopharyngodon idellus, Rhodeus sinensis, Hypophthalmichthys nobilis, Cirrhinus molitorella, Carassius auratus, Cyprinus carpio and Oreochromis niloticus was 1 792, 16, 8, 6, 5, 4, 4, and 2, respectively.Rats and cats were fed with metacercariae from fish to receive adult worms.Conclusion Life cycle of Clonorchis sinensis has been established and maintained in the laboratory.