Trematode - Fasciola hepatica & Clonorchis sinensis (Life Cycles)

*Liver flukes: Fasciola hepatica (sheep liver fluke) and Clonorchis sinensis* (Chinese liver fluke)

Fasciola hepatica* is ingested with aquatic plants, particularly watercress. – Infection can produce pain in the upper right quadrant, hepatic enlargement, and, in serious cases, liver rot (necrosis) and portal cirrhosis. Clonorchis sinensis* is ingested with raw or undercooked freshwater fish. – Infection can produce fever, pain, gastrointestinal problems, and inflammation of the biliary and pancreatic structures. – Chronic inflammation is associated with cholangiocarcinoma (biliary duct cancer). 1. Miracidia invade snail and give rise to cercariae. 2. Cercariae leave snail. 3. Encyst as metacercariae on aquatic plants (example: watercress). 4. Humans eat the plants, ingest metacercariae. 5. Metacercariae excyst in duodenum, pass through intestinal wall and migrate to biliary ducts. – In biliary ducts, they mature to adult flukes. – Adult flukes reproduce (self-fertilization). 6. Eggs are released in feces. 7. Eggs in water release miracidia. 1. Snails ingest eggs - other tissue flukes invade snails as larval forms 2. In snail, eggs release miracidia; miracidia give rise to cercariae. 3. Cercariae exit snails. 4. They invade fish, and encyst as metacercariae. 5. Humans ingest infective metacercariae with undercooked, smoked, pickled, salted freshwater fish. 6. Metacercariae excyst in duodenum; flukes migrate to the biliary ducts and reproduce (self-fertilization). 7. Eggs are excreted in the feces. https://commons.wikimedia.org/wiki/File:Fasciola_hepatica_(Linnaeus,_1758)_2013_000-2.jpg https://commons.wikimedia.org/wiki/File:Fasciola-hepatica-adults.jpg https://www.cdc.gov/parasites/fasciola/diagnosis.html