Liver Fluke

What are liver flukes?

Liver flukes are parasitic worms (nematodes) that can infect and damage your liver, gallbladder and bile ducts. Parasites are organisms that live off of the nutrients of a host. You can get them from eating raw or undercooked fish, watercress or other water plants, or from drinking contaminated water. Livestock, like sheep and cattle, and domestic animals, like cats and dogs, can also be infected.

While they aren’t fatal on their own, liver flukes can live a long time in your body. This chronic infection can cause inflammation and organ damage, sometimes leading to cancer and other serious health conditions.

What are the types of liver flukes?

Types of liver flukes that infect humans include:

• Clonorchis sinensis. Clonorchis sinensis is the most common cause of liver fluke infections. Clonorchis infections are called clonorchiasis.
• Opisthorchis. Two types of Opisthorchis liver fluke, O. viverrini (Southeast Asian liver fluke) and O. felineus (cat liver fluke), infect humans. O. viverrini is the second most common cause of liver fluke infections. Opisthorchis infections are called opisthorchiasis.
• Fasciola. Two types of Fasciola liver fluke, F. hepatica and F. gigantica, infect humans. Fasciola infections are called fascioliasis. Fascioliasis is more common in livestock than in humans.

What are the symptoms of liver fluke infections?

Symptoms of all types of liver flukes infections include:

• Nausea.
• Vomiting.
• Belly (abdominal) pain or tenderness.
• Diarrhea.
• Constipation.
• Fever.
• Chills.
• Rash.
• Shortness of breath (dyspnea).
• Muscle aches.
• Swollen lymph nodes.
• Sore joints.

Some people don’t have symptoms or don’t recognize the symptoms right away.

What causes a liver fluke infection?

Opisthorchis and C. sinensis larvae (young worms) in fluid-filled shells (cysts) infect freshwater fish. Cysts of Fasciola liver fluke larvae live in water and can collect on watercress and other plants. You can get a liver fluke if you eat something infected with or contaminated by the cysts. The cysts open in your digestive tract and the larvae migrate and mature in your liver, gallbladder and bile ducts.

How do you get a liver fluke?

You can get infected with a liver fluke if you:

• Eat raw or undercooked fish. Lightly salted, smoked or pickled fish can put you at risk.
• Eat raw watercress or other water plants that could be contaminated.
• Drink or accidentally swallow contaminated water.
• Eat vegetables that were washed in or irrigated with contaminated water.

Are liver flukes contagious?

No, liver flukes aren’t contagious (they don’t spread from person to person).

What are the risk factors for liver fluke infection?

You’re at higher risk of liver fluke infection if you live in or travel to regions that have liver flukes and work with cattle or sheep.

Where are liver flukes found?

Liver flukes need to live and reproduce in specific conditions. So, while they’re found around the world, they’re more commonly found in specific local regions, rather than spread out in all areas of a country. Different liver flukes are found in different parts of the world:

• F. hepatica is found on every continent except Antarctica. There are high infection rates in humans in parts of Bolivia, Peru, Portugal and Puerto Rico. 
• F. gigantica is found in tropical regions (including Hawaii) and parts of Africa and Asia.
• C. sinensis is found in China, South Korea, Taiwan, Vietnam and Russia.
• O. viverrini is found in parts of Asia, including Thailand, Laos, Cambodia, and Vietnam.
• O. felineus is found in parts of Europe. Human infections have been reported in Russia, Belarus, Ukraine, Kazakhstan, Germany and Italy.

What are the complications of liver flukes?

If left untreated, liver fluke infections can lead to:

• Malnutrition.
• Enlarged liver (hepatomegaly).
• Liver scarring (fibrosis).
• Gall bladder inflammation (cholecystitis).
• Bile duct inflammation (cholangitis).
• Bile duct cancer (cholangiocarcinoma).

Liver flukes can also move to other parts of your body, including your:

• Pancreas.
• Lungs.
• Skin.
• Urinary tract.
• Eyes.
• Brain.

How are liver flukes diagnosed?

To diagnose a liver fluke, a provider looks for parasites in a stool (poop) sample. They may need to test more than one sample over time. You may also need:

• Blood tests. A provider uses blood tests to check for antibodies to the parasite (serology), check your liver function and look for elevated eosinophils, which can be a sign of a parasitic infection.
• Imaging. Your provider might be able to see evidence of a liver fluke infection (like cysts) on ultrasound, CT (computed tomography scan) or MRI (magnetic resonance imaging).
• Liver biopsy. A provider can look for signs of parasites in a sample of tissue from your liver.

How do you get rid of liver flukes?

Providers treat liver fluke infections with antiparasitic medications, including:

• Triclabendazole (Fasciola infections).
• Praziquantel (Opisthorchis and Clonorchis infections).
• Albendazole (Opisthorchis and Clonorchis infections).

Can you prevent liver fluke infections?

Ways you can reduce your risk of liver fluke infections include:

• Don’t eat raw watercress and other water plants.
• Don’t eat raw or undercooked freshwater fish. This includes smoked, pickled or lightly salted fish. Cook fish to temperatures recommended by the FDA (Food and Drug Administration).
• Thoroughly wash, peel or cook vegetables.
• If you’re in an area with poor sanitation or where the water could be contaminated, drink and cook with bottled water.
• Avoid getting potentially contaminated water (especially from marshes, ponds or flooded pastures) in your mouth or nose.

What can I expect if I have a liver fluke infection?

Liver flukes are treatable with a short course (one to seven days) of antiparasitic drugs. If left untreated, liver flukes can live in your body anywhere from five to 25 years. People with a long-lasting infection can have liver, gall bladder and bile duct damage, which can lead to serious health issues.

When should I see my healthcare provider?

See a healthcare provider if you have symptoms of a liver fluke infection, especially if you live in or have traveled to a place where they’re common. Let your provider know if you think you could’ve eaten or drunk something contaminated, even if it was years ago.

When should I go to the ER?

Go to the emergency room if you experience symptoms of severe illness, including:

• Fever over 103 degrees Fahrenheit or 40 degrees Celsius.
• Severe vomiting or diarrhea.
• Confusion or disorientation.
• Yellowing of your skin or eyes (jaundice).
• Dehydration symptoms (like extreme thirst, peeing very little, weakness and high heart rate).

What questions should I ask my doctor?

It might be helpful to ask your healthcare provider:

• How do I take this medication?
• How long will it take to feel better?
• How long have I had this infection?
• Do I have any lasting damage?
• What’s the outlook for my condition?

Are liver flukes common in humans?

An estimated 50 million people are infected with some form of liver fluke worldwide. Infections are most common in parts of China, Thailand and Russia.

Why is it called liver fluke?

A fluke is a common name that people call trematodes, or a type of parasitic flatworm. Some people might confuse it with a flat fish with eyes on one side of its body (flounder), which is also called a fluke.

A note from Cleveland Clinic

Liver fluke infections are rare in the U.S. But it’s estimated that millions of people around the world could be infected — some without even knowing it. It’s important to know the symptoms of an infection if you’re living in or traveling to an area where one of the types of liver fluke live. If you have symptoms, be sure to let your provider know if you think you could’ve eaten something contaminated. A long-term infection can cause serious illnesses, and treatment is usually quick and effective.