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Clonorchis FAQs

What is Clonorchis?

Clonorchis is a liver fluke that can infect the liver, gallbladder and bile duct. Found across parts of Asia, it is also known as the Chinese or oriental liver fluke.

How does one become infected with Clonorchis?

The eggs of Clonorchis sinensis are ingested by snails in fresh water. After the eggs hatch, infected snails will release microscopic larvae that will enter freshwater fish. People become infected when eating the parasite containing cysts within infected raw or undercooked fish. Once ingested, cysts travel to the small intestine and liver where they feed upon the bile created by the liver and mature. The life cycle takes 3 months to complete in humans. Infected people will then pass eggs in their feces or may cough them up.

Where is Clonorchis found?

Chlonorchis is found in Asia including Korea, China, Taiwan, Vietnam, Japan, and Asian Russia. When clonorchiasis has been reported in non-endemic areas, the infection was found in Asian immigrants. Some cases were found in people who had ingested imported, undercooked or, pickled freshwater fish containing parasitic cysts.

What do I do if I think I have clonorchiasis?

See your health care provider if you think you may have been exposed to Clonorchis.

How is it diagnosed?

The detection of eggs in stool is the most common way to diagnose the infection. Sometimes an endoscopy is done to examine the small intestine for eggs. Additionally, ultrasound, CT, and MRI scanning may be used to discover parasite-containing cysts that contribute to a diagnosis.

Can Clonorchis be transmitted person to person?

No. Clonorchis cannot be directly transmitted from person to person.

What are the signs and symptoms?

Most signs and symptoms are related to inflammation and intermittent obstruction of the biliary ducts. In severe cases, abdominal pain, nausea, and diarrhea can occur. In long-standing, untreated infections, inflammation of the biliary system can lead to cancer, which can be fatal.

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  • Page last reviewed: November 25, 2014
  • Page last updated: November 25, 2014
  • Content source: Global Health - Division of Parasitic Diseases and Malaria
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