[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Liver fluke infections (fascioliasis, clonorchiasis, opisthorchiasis)

[Conditions](https://durgical.com/en/conditions/) · [Infectious and tropical diseases](https://durgical.com/en/conditions/)

# Liver fluke infections (fascioliasis, clonorchiasis, opisthorchiasis)

Flat worms caught from watercress or raw fish that live in the bile ducts and can cause pain, fever, jaundice and, over years, [bile duct](https://durgical.com/en/anatomy/bile-duct/) cancer.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Common bile duct](https://durgical.com/en/anatomy/bile-duct/)
- [Liver](https://durgical.com/en/anatomy/liver/)
- [Gallbladder](https://durgical.com/en/anatomy/gallbladder/)
- [Common hepatic duct](https://durgical.com/en/anatomy/common-hepatic-duct/)
- [Cystic duct](https://durgical.com/en/anatomy/cystic-duct/)
- [Ampulla of Vater](https://durgical.com/en/anatomy/hepatopancreatic-ampulla/)
- [Pancreas](https://durgical.com/en/anatomy/pancreas/)
- [Pancreatic duct](https://durgical.com/en/anatomy/pancreatic-duct/)
- [Duodenum](https://durgical.com/en/anatomy/duodenum/)
- [Portal vein](https://durgical.com/en/anatomy/hepatic-portal-vein/)

## Why it happens

- [Precancerous conditions: when chronic inflammation, metaplasia or hyperplasia raise the risk](https://durgical.com/en/general-pathology/precancerous-conditions-when-chronic-inflammation-metaplasia-or-hyperplasia-rais/)
- [Oncogenic viruses and H. pylori: the table to know](https://durgical.com/en/general-pathology/oncogenic-viruses-and-h-pylori-the-table-to-know/)
- [Bile and the enterohepatic circulation](https://durgical.com/en/physiology/bile-and-the-enterohepatic-circulation/)
- [Gallbladder and bile ducts](https://durgical.com/en/histology/gallbladder-and-bile-ducts/)

## What it is

Foodborne trematode infections in which adult flukes live in the bile ducts. Fasciola hepatica, acquired from watercress and other water plants, is the species of the Americas; Clonorchis sinensis and Opisthorchis species, acquired from raw freshwater fish, are mainly Asian. They cause an acute migratory phase with fever and liver tenderness and a chronic biliary phase with obstruction, cholangitis and, for Clonorchis and Opisthorchis viverrini, a raised risk of cholangiocarcinoma.

## Who gets it

Fascioliasis is a global zoonosis of sheep and cattle with high human burdens reported in Latin America, especially the Andean highlands of Bolivia and Peru, where children are heavily affected. Fasciola infection of cattle is common in livestock areas of the Andes, and sporadic human cases occur in Colombia, linked to watercress and other raw vegetables. Clonorchiasis and opisthorchiasis are concentrated in East and Southeast Asia and appear in Colombia mainly as imported cases.

## Causes

- Fasciola hepatica (and F. gigantica): metacercariae encyst on watercress and other aquatic plants or in water; sheep and cattle are the main hosts
- Clonorchis sinensis and Opisthorchis viverrini or O. felineus: metacercariae in raw, pickled or undercooked freshwater fish
- Freshwater snails are required intermediate hosts for all of them
- Paragonimiasis (lung flukes from raw crabs or crayfish) is a related foodborne trematode infection that can be considered together

## Risk factors

- Eating raw watercress or drinking untreated water in livestock-raising areas (Fasciola)
- Eating raw or undercooked freshwater fish (Clonorchis, Opisthorchis)
- Living in rural Andean or Asian endemic areas
- Long-standing heavy infection and reinfection (cancer risk)

## Pathophysiology

Swallowed larvae excyst in the [duodenum](https://durgical.com/en/anatomy/duodenum/). Fasciola penetrates the bowel wall, crosses the [peritoneum](https://durgical.com/en/anatomy/peritoneum/) and burrows through the liver capsule and parenchyma for weeks, leaving necrotic tracks and causing fever, pain and eosinophilia; after about 3–4 months it settles and lays eggs in the large bile ducts. Clonorchis and Opisthorchis instead climb directly through the ampulla into the bile ducts. In the ducts, flukes cause mechanical irritation, epithelial hyperplasia, periductal fibrosis and obstruction, favouring stones, bacterial cholangitis and, with chronic inflammation, cholangiocarcinoma.

## Classification

- Fascioliasis: acute hepatic (migratory) phase and chronic biliary phase; ectopic forms ([skin](https://durgical.com/en/anatomy/skin/), other organs)
- Clonorchiasis and opisthorchiasis: usually silent; chronic biliary disease and cholangiocarcinoma
- Paragonimiasis (lung fluke): chronic cough, blood-stained sputum, mimics tuberculosis

## Symptoms and signs

- Acute fascioliasis: fever, right upper quadrant pain, tender enlarged liver, urticaria, weight loss
- Chronic phase: intermittent biliary colic, dyspepsia, episodes of jaundice
- Fever with jaundice and pain when cholangitis develops
- Many chronic and light infections cause no symptoms

## Red flags

- Fever, jaundice and right upper quadrant pain (acute cholangitis)
- Hypotension or confusion with biliary symptoms (septic cholangitis)
- Painless jaundice, weight loss and a palpable gallbladder in a long-infected person (cholangiocarcinoma)
- Severe epigastric pain radiating to the back (pancreatitis)

## Diagnosis

**Clinical**
Suspected in fever with right upper quadrant pain, hepatomegaly and marked eosinophilia, or in recurrent biliary symptoms, in someone who has eaten watercress or raw fish in an endemic area.

**Tests**
Blood count with eosinophilia (prominent in the acute phase); [liver](https://durgical.com/en/anatomy/liver/) tests with cholestatic pattern. Stool or duodenal aspirate for eggs, positive only in the chronic phase and often requiring several samples. Fasciola serology, useful in the acute phase before eggs appear. Fasciola antigen in stool where available.

**Imaging**
Ultrasound and CT show hypodense, branching tracks in the liver in acute fascioliasis, and dilated ducts or flukes in the bile ducts or [gallbladder](https://durgical.com/en/anatomy/gallbladder/) in the chronic phase. MRCP or ERCP visualises the ducts; ERCP can also remove flukes.

## Differential diagnosis

- Choledocholithiasis and acute cholangitis from stones
- Amoebic or pyogenic liver abscess
- Echinococcosis and toxocariasis
- Cholangiocarcinoma, primary sclerosing cholangitis
- Acute viral hepatitis

## Goal of treatment

Eradicate the flukes with the drug that works for each species, relieve biliary obstruction and infection, and detect cholangiocarcinoma early in long-standing Asian fluke infection.

## Treatment

**Medical**
Fascioliasis: triclabendazole is the drug of choice; praziquantel does not work against Fasciola. Nitazoxanide is a less effective alternative.

**Medical**
Clonorchiasis, opisthorchiasis and paragonimiasis: praziquantel. Antibiotics for bacterial cholangitis, with fluids and analgesia.

**Procedure**
ERCP with sphincterotomy to extract flukes and stones and drain the bile ducts when there is obstruction or cholangitis; surgery for complications or cancer.

**Follow-up**
Repeat stool tests and eosinophil count to confirm cure; follow liver tests and imaging; watch for biliary colic during treatment as dying flukes pass through the ducts.

## Complications

- Acute bacterial cholangitis and liver abscess
- Gallstones and biliary obstruction
- Acute pancreatitis
- Secondary biliary cirrhosis
- Cholangiocarcinoma (Clonorchis and Opisthorchis viverrini are classified as carcinogens)
- Anemia, growth delay in children

## Prognosis

With the right drug, most infections are cured and acute symptoms resolve, although eosinophilia and imaging changes take months to normalise. Long-standing Asian fluke infection carries a lasting risk of cholangiocarcinoma, which has a poor prognosis.

## Prevention

- Not eating raw watercress or other aquatic plants from areas where livestock graze
- Cooking freshwater fish and crustaceans; avoiding raw, pickled or smoked preparations
- Treating infected livestock and controlling snails
- Preventive chemotherapy in high-burden communities

## Test yourself

Think of the answer, then tap the question to see it.

## How do humans acquire Fasciola hepatica?

By eating watercress or other aquatic plants (or water) contaminated with metacercariae, in livestock-raising areas.

## What is the drug of choice for fascioliasis?

Triclabendazole; praziquantel is ineffective against Fasciola.

## Which liver flukes are linked to cholangiocarcinoma?

Clonorchis sinensis and Opisthorchis viverrini, acquired from raw freshwater fish.

## Why may stool tests be negative in acute fascioliasis?

The flukes are still migrating through the liver and do not lay eggs until they reach the bile ducts after about 3–4 months; serology helps then.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/conditions/liver-fluke-infections/)

## Related conditions

- [Acute cholangitis](https://durgical.com/en/conditions/acute-cholangitis/)
- [Cholangiocarcinoma (bile duct cancer)](https://durgical.com/en/conditions/cholangiocarcinoma/)
- [Choledocholithiasis](https://durgical.com/en/conditions/choledocholithiasis/)
- [Acute cholecystitis](https://durgical.com/en/conditions/acute-cholecystitis/)
- [Acute pancreatitis](https://durgical.com/en/conditions/acute-pancreatitis/)
- [Amoebic liver abscess](https://durgical.com/en/conditions/amoebic-liver-abscess/)
- [Pyogenic liver abscess](https://durgical.com/en/conditions/pyogenic-liver-abscess/)
- [Echinococcosis (hydatid disease)](https://durgical.com/en/conditions/echinococcosis/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Foodborne trematode infections](https://www.who.int/news-room/fact-sheets/detail/foodborne-trematode-infections) (World Health Organization, 2025); [CDC - DPDx - Fascioliasis](https://www.cdc.gov/dpdx/fascioliasis/index.html) (Centers for Disease Control and Prevention, 2019).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/conditions/liver-fluke-infections/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/liver-fluke-infections/