Clonorchis species are liver fluke parasites (trematodes or worms) such as fasciola hepatica.
Liver fluke infections occur mostly in people living in some areas where the parasites are found. Clonorchis is found mainly in Korea, China, Taiwan, Northern Vietnam, Japan, and Asian Russia.
Travelers to Asia who consume raw or undercooked fish are at risk for liver fluke infection.
People become infected by eating raw or undercooked freshwater fish containing the larvae.
Lightly salted, smoked, or pickled fish may contain infectious parasites.
Drinking river water or other non-potable water will not lead to infection with Clonorchis.
Clonorchis sinensis eggs are discharged in the biliary ducts and in the stool in an embryonated state.
Eggs are ingested by a suitable snail intermediate host
Eggs release miracidia image , which go through several developmental stages
The cercariae are released from the snail and, after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae
Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish
After ingestion, the metacercariae excyst in the duodenum image and ascend the biliary tract through the ampulla of Vater
Maturation takes approximately one month.
The adult flukes (measuring 10 to 25 mm by 3 to 5 mm) reside in small and medium sized biliary ducts.
Do not eat raw or undercooked freshwater fish. Lightly salted, smoked, or pickled fish can contain infectious parasites. Drinking river water or other non-potable water will not lead to infection with Clonorchis.
The FDA recommends the following for fish preparation or storage to kill any parasites.
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