A Chinese liver fluke is a parasite that can cause a worm disease, clonorchiose, in humans. Not always symptoms indicate.

What is a Chinese liver fluke?

An infection with the clonorchiasis occurs mainly through the consumption of uncooked or raw carp-like freshwater fish. A Chinese liver fluke keeps itself in muscles and skin of the intermediate host fish.
© Dr. N. Lange - stock.adobe.com

A Chinese liver fluke (Clonorchiasis) is one of the suckling worms and occurs mainly in the areas of South and East Asia. However, related species of the parasite clonorchiasis can also be found beyond Asia beyond Eastern Europe.

Clonorchiasis invests as end hosts in humans and mammals feeding on freshwater fish. Clonorchiasis stays in the liver and biliary tract of its final host and lays its eggs here. An adult Chinese liver fluke can reach a length of up to 25 millimeters.

If a person is attacked by clonorchiasis, this is also called clonorchiosis. This worm disease caused by clonorchiasis is one of the world's three most common worm diseases. According to World Health Organization (WHO) estimates, up to 30 million people worldwide have a Chinese liver fluke.


An infection with the clonorchiasis occurs mainly through the consumption of uncooked or raw carp-like freshwater fish. A Chinese liver fluke keeps itself in muscles and skin of the intermediate host fish.

If a person becomes infected with clonorchiasis, it invades the small intestine; from here, larvae of clonorchia proceed in the liver and biliary tract. Having reached the biliary tract, the larvae of clonorchia develop into mature parasites. Eggs of adult Chinese liver fluke are excreted via the human feces and can thus get back into the fresh water cycle.

When these eggs are picked up by freshwater snails, the clonorchiasis migrates from freshwater snail to freshwater fish at various stages of development and eventually to the end host.

Symptoms, complaints & signs

The clonorchiasis is always associated with discomfort in the stomach and stomach. These complaints are very uncomfortable and can make the daily life of the person concerned significantly more difficult. In the first place it comes to complaints at the bile ducts. These are inflamed in a clonorchiasis and can therefore be painful or irritated.

As a rule, this results in a strong feeling of fullness, which can occur even without food intake. Furthermore, most patients suffer from persistent diarrhea, which can lead to [dehydration] 9 and various deficiency symptoms if the losses are not compensated. In the further course it comes to a bile blockage, if the clonorchiasis is not treated. In severe cases, the gallbladder must be completely removed.

However, the infection can also spread to the other areas of the body and also infect other internal organs. This can cause discomfort to the liver or kidneys. In the worst case, the person dies of liver failure or renal insufficiency. The clonorchiasis can usually be cured well, if the therapy starts early. Late onset can also cause long-term damage that can not be treated anymore.

Diagnosis & History

Although symptoms caused by a Chinese liver fluke in humans (such as diarrhea or inflammation of the biliary tract) may indicate an infection with clonorchiasis.

However, as these clonorchial symptoms are very nonspecific, a Chinese liver fluke or eggs must usually be diagnosed by examining a patient's stool or bile. Also using the secretion from the duodenum of a person affected by an infection can be detected by the clonorchiasis.

The course of an infection with the clonorchiasis can be very different depending on the patient; Often a corresponding infection is symptom-free. Symptoms often only occur when a patient has more than 100 copies of the Chinese liver fluke. The incubation period (ie the time between infection by clonorchiasis and ripening of adult Chinese liver fluke) is about 4 weeks.

Possible long-term consequences of the infestation of Chinese liver fluke include altered tissue structures of bile. Without proper treatment, excretion of eggs from Chinese liver fluke by a person affected can last up to 30 years.


The Chinese liver fluke nestles mainly in the bile ducts and leads there to various complications. Those affected usually experience loss of appetite, which in conjunction with the typical diarrhea can lead to deficiency symptoms, dehydration and other problems. As a result of gallbladder inflammation, it can lead to the breakdown of the intestinal wall, the formation of fistulas or gallstones.

Rarely, it also leads to jaundice or inflammation of the pancreas, which in turn is associated with serious complications. If the liver fluke is not recognized, it nestles sometimes for a lifetime in the bile ducts and lays there again and again eggs. The constant irritation of the bile ducts increases the risk of malignant diseases such as bile cancer or cirrhosis.

In extreme cases, the liver and spleen enlarge and organ failure occurs. Chronic infestation can also lead to a "porcelain gallbladder" that causes limescale deposits in the gallbladder wall that can cause carcinomas and gallstones. If the Chinese liver fluke is detected and treated early, severe complications are rare. However, commonly used drugs such as albendazole can cause side effects such as anemia, rash and itching.

When should you go to the doctor?

In case of suspected infection with the Chinese liver fluke, a doctor should be consulted immediately. While there is no acute risk to most individuals, the sooner the parasite is destroyed, the lower the risk of long-term damage, which may include severe complications such as pancreatitis, cirrhosis, or bile duct carcinoma.

Patients who are or have recently been found to be at risk should therefore be alert to any relevant symptoms. These include not only loss of appetite, bloating and indigestion with diarrhea and gallbladder inflammation and liver inflammation. Sometimes jaundice sets in, which is recognized by the discoloration of the eyes and the skin. If you have such signs, you should urgently see a doctor.

The Chinese liver fluke is mainly distributed in East Asia. The Saugwurm arrives mostly by the consumption of raw or not completely durchgegarten fish in the human body. Transmission through contaminated drinking water is also possible. If the treating physician does not ask for it himself, those affected must explicitly point out the presence of such risk factors.

Treatment & Therapy

An effective treatment of the Chinese liver fluke infection may link the cause treatment with the treatment of symptoms that can be caused by the clonorchiasis. A fight against the infection with the Chinese liver fluke is for example possible by the gift of corresponding worm poisons.

Such worm poisons for combating clonorchiasis include, for example, the active ingredient praziquantel. If deworming has been successfully performed in the presence of Chinese liver fluke, it is common practice to control treatment success after about 3 weeks.

A symptomatic therapy that may accompany the treatment of the causes of infection by the clonorchiasis, for example, in the relief of occasional early symptoms such as bloating, loss of appetite or diarrhea. For example, diarrhea caused by clonorchiasis can be counteracted by adequate supply of fluid and electrolytes; rarely and in case of very severe diarrhea it can also be combated with medication.

Outlook & Forecast

In case of clonorchiasis a relatively simple and effective treatment can be carried out so that the disease can be completely restricted. Special symptoms or complications do not occur and there is a positive course of the disease.

The treatment of clonorchiasis is done with the help of drugs that kill the worm. The affected person suffers from the symptoms of the infection, which, however, decay with time and eventually disappear completely. There are no consequential damages if treatment starts early.

If the clonorchiasis is not treated, it can lead to serious diseases in the stomach and intestine of the patient, which can lead to death in the worst case. However, death from clonorchiasis is relatively rare and only occurs when symptoms are completely ignored.

Due to the severe diarrhea, patients rely on increased fluid and nutrient intake to rebalance nutrient losses. If this does not happen, it can lead to deficiency symptoms or dehydration. Successful treatment of clonorchiasis does not adversely affect the patient's life expectancy.


Preventing an attack by Chinese liver fluke especially by careful food intake; Freshwater fish should only be consumed in a sufficiently cooked condition (usually a heating above 55 ° C leads to the death of possible worm larvae) in order to avoid uptake of clonorchiasis through the diet. In addition, hygiene measures can help prevent human excreta and thus eggs from the Chinese liver fluke from entering freshwater ponds.


After a medical treatment of the Chinese liver fluke (clonorchiasis) usually no follow-up examinations are necessary. By the drug treatment of the disease, the parasite is killed and eliminated with the bowel movement. If the drug is taken early and after medical advice, the Chinese liver fluke (clonorchiasis) can be so completely eliminated from the body, without leaving any sequelae.

If there is no renewed infection with the parasite, the symptoms should be promptly disappeared and a normal rhythm of life can re-occur. A week of relief for the intestine, which consumes mainly soups and light-digestible food, can help to cleanse the stomach and intestinal tract after the illness and to make them fit. In the pharmacy bacteria can be acquired, which are involved in the reconstruction of a healthy intestinal flora.

If the parasite infestation persists for an extended period of time, possibly even years, without being discovered, secondary diseases of the internal organs can arise. Any damage to the pancreas, bile ducts, liver and spleen must then be treated separately. Inflammation and malignant changes such as bile cancer require more extensive medical treatment and are associated with serious symptoms.

Therefore, it is advisable to consult a doctor in case of complaints in the gastrointestinal tract that occur after traveling to other countries or as a result of eating unfamiliar food. Thus, consequential damage caused by the Chinese liver fluke (clonorchiasis) can be prevented and a comprehensive follow-up treatment can be omitted.

You can do that yourself

The Chinese liver fluke is a parasite which, despite its name, mainly affects the bile ducts. Although those affected do not immediately develop severe symptoms, a clonorchiasis is very serious and should be urgently treated in a timely manner.

Therefore, an important contribution to self-help is to identify the parasite infestation as early as possible. The parasite occurs mainly in Southeast Asia, where about 40 million people are suffering from it. Anyone who notices certain symptoms per se after a holiday or vacation in this region should seek medical treatment promptly and explicitly inform the attending physician about long-distance travel.

The first signs of clonorchiasis include loss of appetite, bloating and diarrhea. In the next stage it often comes to an inflammation of the gallbladder, which is accompanied by severe pain in the right upper abdomen, and liver inflammation. As far as an affected person should not let it come, but immediately at the first sign of digestive problems after a long-distance travel to see the doctor.

In addition, the patient can help prevent infection. The biggest risk is the consumption of raw freshwater fish. Travelers should therefore make sure that they consume only fish dishes that are properly cooked or roasted or, much better, completely abstain from eating fish. This also applies to accompanying pets such as dogs or cats, which can also be attacked by the worm.

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