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Clonorchis sinensis

Common name. Oriental liver fluke, Chinese liver fluke

Disease. Clonorchiasis

Geographic distribution. China, Korea, Russia, Taiwan, Hong Kong, and Vietnam

Infection rate. The total number of persons infected worldwide is estimated more than 20 million.

Life cycle. The adult worms live in the bile ducts of the final hosts. The eggs pass out with the feces and hatch to miracidia when ingested by suitable freshwater snails (first intermediate hosts). Stages of sporocyst, redia, and cercaria undergo in snails, i.e., Parafossarulus manchouricus. Mature cercariae hatch into the water and infect freshwater fish of Family Cyprinidae (second intermediate hosts) to make encysted metacercariae in the muscle. The final hosts get infected by ingesting raw or undercooked fish. The important final hosts are humans, dogs, cats, pigs, and rodents.

Morphology. Adult worms are flat, slender leaf-shaped between 10 and 25 mm in length, and two branched testes are located in posterior one third. The yellow to light brown eggs measure about 30 by 15 ㎛. The operculum has prominent shoulder rim, and on the opposite side, comma shaped terminal knob locates.

Pathology and clinical symptoms. The mechanical irritation and toxic metabolites of the parasite cause inflammatory responses in biliary epithelium. Obstruction of biliary tract, pyogenic cholangitis, pancreatitis, cholecystitis, cholelithiasis, liver cirrhosis, and cholangiocarcinoma may be induced as the result of heavy and chronic infection.

Diagnosis. Detection of eggs in feces makes definite diagnosis. ELISA and radiologic techniques (mainly sonography) can provide indirect evidences of clonorchiasis.

Prevention. Avoiding ingestion of raw fresh-water fish.

Comments. Differential diagnosis from heterophyid eggs is necessary.

Sung-Tae Hong


Egg of Clonrochis sinensis. Operculum, shoulder rim and surface wrinkling are distinctive. Length of 28-30 micrometer, width 14-18 micrometer.

Sung-Tae Hong


Clonorchis sinensisegg.

Tai Soon Yong


Egg of Clonorchis sinensis. 29 um x 15 um.

Sung-Jong Hong


Egg of Clonorchis sinensis. 30 um x 16 um.

Sung-Jong Hong


Egg of Clonorchis sinensis. 29 um x 15 um.

Sung-Jong Hong


Egg of Clonorchis sinensis. 29 um x 16 um.

Sung-Jong Hong


An amorphous egg of Clonorchis sinensis longer than the typical ones. 33 um x 16 um.

Sung-Jong Hong


An amorphous egg of Clonorchis sinensis widerer than the typical ones. 27 um x 18 um.

Sung-Jong Hong


The egg of Clonorchis sinensis from human.

Woon-Mok Sohn


The egg of C. sinensis from a cat.

Woon-Mok Sohn


Egg of C. sinensis from human.

Woon-Mok Sohn


Metacercariae of Clonorchis sinensis collected from digested fish. The cyst wall is elliptical 0.16-0.20 mm long. Dark granules are in the bladder.

Sung-Tae Hong


A metacercaria of Clonorchis sinensis. The larva in the cyst wall is actively moving. Note two suckers and a excretory bladder filled with dark granules. x150.

Sung-Tae Hong


Cercaria of Clonorchis sinensis. The cercaria is liberated from its first intermediate host, a fresh water snail.

Tai Soon Yong


Metacercaria of Clonorchis sinensis collected from Pseudorasbora parva. x400.

Sung-Jong Hong


Metacercaria of Clonorchis sinensis isolated from P. parva.

Woon-Mok Sohn


Metacercaria of Clonorchis sinensis isolated from P. parva.

Woon-Mok Sohn


Metacercaria of Clonorchis sinensis isolated from Pungtungia herzi.

Woon-Mok Sohn


Clonorchis sinensis adult worms (about 2900) recovered from a heavy infected case during surgery of gall bladder.

Sung-Tae Hong


A destroyed Clonorchis sinensis by praziquantel treatment. Only anterior part and the body margin remained.

Sung-Tae Hong


Fresh adult worms of Clonorchis sinensis recovered from experimentally infected rabbits. Worms in the right side are 4 weeks old and those in the left are 12 weeks old. The worm is grossly red but the intestinal ceca and distal uterus are dark.

Sung-Tae Hong


Adult Clonorchis sinensis, acetocarmine stained. Its uterus is full of eggs, ovary and two tandem branched testes are seen well.

Sung-Tae Hong


Clonorchis sinensis : from liver of rabbit, Acetocarmine stain, X40

Yong Suk Ryang




Clonorchis sinensis collected from a patient.

Sung-Jong Hong


Clonorchis sinensis collected from a patient.

Sung-Jong Hong


Clonorchis sinensis collected from a naturally infected cat. Semichon's acetocarmine stained.

Woon-Mok Sohn


C. sinensis collected from a naturally infected cat. Semichon's acetocarmine stained.

Woon-Mok Sohn


An Israeli carp, Cyprinus carpio nudus, one of favourate freshwater fish for eating raw.

Sung-Tae Hong


Pseudorasbora parva, the most suitable freshwater fish host of Clonorchis sinensis.

Sung-Tae Hong


A man caught freshwater fish in an endemic village of clonorchiasis, China.

Sung-Tae Hong


Favourite freshwater fish in the endemic village of clonorchiasis in China.

Sung-Tae Hong


A woman preparing sliced raw freshwater fish.

Sung-Jong Hong


Topmouth gudgeons, Pseudorasbora parva, one of the second intermediat hosts of Clonorchis sinensis.

Sung-Jong Hong


Cyprinus carpio, carp.

Woon-Mok Sohn


Carassius auratus, Crucian carp.

Woon-Mok Sohn


Pseudorasbora parva, top mouth minnow.

Woon-Mok Sohn


Hemibarbus longirostris, long nose barbel.

Woon-Mok Sohn


Pseudogobio esocinus, goby minnow.

Woon-Mok Sohn


Pungtungia herzi, black striped gudgeon.

Woon-Mok Sohn


Coreoleuciscus splendidus.

Woon-Mok Sohn


Microphysogobis yaluensis.

Woon-Mok Sohn


Zacco platypus, pale chub.

Woon-Mok Sohn


Zacco temminckii, dark chub.

Woon-Mok Sohn


Hemibarbus labeo, steel barbel.

Woon-Mok Sohn


Sarcocheilichthys nigripinnis morii, Korean oily shinner.

Woon-Mok Sohn


Sarcocheilichthys variegatus wakiyae, Korean oily shinner.

Woon-Mok Sohn


Acanthorhodeus assumussi, deep body bitterling.

Woon-Mok Sohn


Acanthorhodeus gracilis, Korean spined bitterling.

Woon-Mok Sohn


Culter brevicauda.

Woon-Mok Sohn


Hemiculter eigenmanni.

Woon-Mok Sohn


Acanthorhodeus assumussi, deep body bitterling.

Woon-Mok Sohn


Hypomesus olidus, pond smelt.

Woon-Mok Sohn


Squalidus japonicus coreanus, short barbel gudgeon.

Woon-Mok Sohn


Pseudorasbora parva, top mouth minnow.

Woon-Mok Sohn


Hemiculter leucisculus.

Woon-Mok Sohn


Pungtungia herzi, black striped gudgeon.

Woon-Mok Sohn


Zacco temminckii, dark chub.

Woon-Mok Sohn


A cook is cutting fish in the kitchen to prepare raw sliced fish (sushi) in a restaurant, China.

Sung-Tae Hong


Many restaurants serve raw freshwater fish at the endemic area of clonorchiasis in Korea.

Sung-Tae Hong


View of a branch of the Nakdong-gang, one of endemic area of Clonorchis sinensis.

Sung-Tae Hong


Cutting a freshwater fish to prepare a dish of raw fish (sushi). Eating raw fish is common and favourite habit in Korea.

Sung-Tae Hong


Boys are fishing with a net in a stream at an endemic area of clonorchiasis, China.

Sung-Tae Hong


An intrahepatic bile duct of a rabbit infected with Clonorchis sinensis. The bile duct showes severe papillary and glandular hyperplasia of the mucosa, dilatation, and periductal fibrosis and inflammation. HE stained, x60.

Sung-Tae Hong


Cirrhotic liver of a rabbit with chronic infection of Clonrochis sinensis. Liver margin discolored yellow and became fibrotic. Several worms (dark spots at the yellow part) are seen.

Sung-Tae Hong


The intrahepatic bile duct of an experimentally infected rabbit with Clonorchis sinensis, one year after treatment. Note the persistent duct wall thickening but resolved inflammation, mucosal hyperplasia and lumen dilatation.

Sung-Tae Hong


Metaplasia of mucin-secreting cells (red) in the bile duct mucosa of a rabbit infected with Clonorchis sinensis. PAS stained, x300.

Sung-Tae Hong


Metaplasia of acid mucin-secreting cells (blue) in the bile duct mucosa of the Clonorchis sinensis infected rabbit. Alcian blue stained, x150.

Sung-Tae Hong


A patient with heavy clonorchiasis (EPG 26,000) at an endemic village in China.

Sung-Tae Hong


Pathologic section of the liver of chronic clonorchiasis patient. Note hyperplasia of biliary epithelium and periductal fibrosis.

Sung-Jong Hong


In liver section of chronic clonorchiasis patient, pronounced are the hyperplasia of biliary epithelium and periductal fibrosis.

Sung-Jong Hong


Clonorchis sinensis provoked thickening of biliary epithelium, in which a blood vessel was generated. H & E stained.

Sung-Jong Hong


Liver of a healthy rat.

Woon-Mok Sohn


Liver of a rat infected with C. sinensis.

Woon-Mok Sohn


Liver of a guinea pig infected with C. sinensis.

Woon-Mok Sohn


Ultrasound scanning of the liver can easily make diagnosis of clonorchiasis. Diffuse dilatation of the intrahepatic bile duct and ductal wall thickening are major findings.

Sung-Tae Hong