aetiology and epidemiology
Last reviewed 01/2018
- Clonorchis sinensis is a small fluke (5 by 15mm) that lives in the biliary tree of its host (for a period of up to 50 years).
- the fluke feeds on mucosal secretions (whilst in the biliary tree) and passes operculated eggs into the faeces.
- once the eggs reach freshwater they are ingested by the intermediate snail host.
- The flukes develop and multiply within the snail and the cercariae are released and penetrate freshwater fish.
- infection of man occurs after eating salted, pickled, raw or dried fish that contains the metacercariae.
- the larvae are released in the duodenum and they enter the bile duct. They then progress to second order bile ducts where the flukes mature into the adult forms in about 1 month. Other reservoirs, in addition to humans, are pigs, rats, cats and dogs.
Clonorchis is endemic in Korea, Japan, Taiwan, Hong Kong, Southern China and Vietnam.