Chinese Liver Fluke (clonorchiasis) Explanations

A Chinese liver fluke is a parasite that can cause a worm disease called clonorchiosis in humans. Symptoms don’t always indicate this.

What is a Chinese liver fluke?

A Chinese liver fluke (clonorchiasis) is one of the flukes and occurs mainly in the areas of South and East Asia. Related species of the clonorchiasis parasite can be found beyond Asia but also as far as Eastern Europe.

The clonorchiasis attacks humans and mammals as final hosts that feed on freshwater fish. The clonorchiasis resides in the liver and biliary tract of its ultimate host and lays its eggs here. A fully grown Chinese liver fluke can reach a length of up to 25 millimeters.

If a person is affected by clonorchiasis, this is also known as clonorchiosis. This worm disease caused by clonorchiasis is one of the three most common worm diseases worldwide. According to estimates by the World Health Organization (WHO), a Chinese liver fluke is found in up to 30 million people worldwide.


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

If a person becomes infected with the clonorchiasis, it penetrates the small intestine; from here larvae of the clonorchiasis move in the liver and biliary tract. Once in the biliary tract, the larvae of the clonorchiasis develop into adult parasites. Adult Chinese liver fluke eggs are excreted in human feces and can thus get back into the freshwater cycle.

If these Chinese liver fluke eggs are ingested by freshwater snails, the clonorchiasis migrates in various stages of development from freshwater snail to freshwater fish and finally to the corresponding final host.

Symptoms, ailments & signs

Clonorchiasis is always associated with discomfort in the abdomen and stomach. These complaints are very uncomfortable and can make everyday life much more difficult for those affected. First and foremost, there are complaints of the biliary tract. These are inflamed in clonorchiasis and can therefore be painful or irritated.

As a rule, this leads to a strong feeling of fullness, which can also occur 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 for. Later, if the clonorchiasis is left untreated, biliary congestion occurs. In severe cases, the gallbladder must be completely removed.

However, the infection can spread to other areas of the body and infect other internal organs as well. This can lead to problems with the liver or the kidneys. In the worst case, the affected person dies from liver insufficiency or from kidney insufficiency. Clonorchiasis can usually be cured well if therapy starts early. A late start can also lead to long-term damage that can no longer be treated.

Diagnosis & course

Symptoms that a Chinese liver fluke causes in humans (such as diarrhea or inflammation of the biliary tract) can indicate an infection with the clonorchiasis.

Since these symptoms are very unspecific due to clonorchiasis, a Chinese liver fluke or its eggs usually have to be diagnosed by examining a patient’s stool or bile. An infection by the clonorchiasis can also be determined with the help of the secretion from the duodenum of an affected person.

The course of an infection with the clonorchiasis can vary greatly depending on the patient; a corresponding infection is often symptom-free. Symptoms often do not appear until a patient is infected with more than 100 specimens of the Chinese liver fluke. The incubation period (i.e. the time between infection by the clonorchiasis and the maturation of adult Chinese liver fluke) is approx. 4 weeks.

Possible long-term consequences of the Chinese liver fluke infestation include altered tissue structures in the bile. Without adequate therapy, shedding of Chinese liver fluke eggs by an affected person can take up to 30 years.


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

This rarely results in jaundice or inflammation of the pancreas, which in turn is associated with serious complications. If the liver fluke is not recognized, it sometimes nests in the bile ducts for a lifetime and lays eggs there again and again. The constant irritation of the biliary tract increases the risk of malignant diseases such as biliary carcinoma or cirrhosis of the liver.

In extreme cases, the liver and spleen enlarge and organ failure occurs. A chronic infestation can also lead to a “porcelain gallbladder”, in which calcium deposits develop in the gallbladder wall, which can cause carcinomas and gallstones. If the Chinese liver fluke is recognized and treated early, serious complications rarely occur. Commonly used active ingredients such as albendazole can, however, cause side effects such as anemia, rash and itching.

When should you go to the doctor?

If you suspect an infection with the Chinese liver fluke, a doctor should be consulted immediately. Although there is no acute danger for most of those affected, the earlier the parasite is destroyed, the lower the risk of long-term damage, which can include serious complications such as pancreatitis, cirrhosis of the liver or carcinoma of the bile duct.

Patients who are or have recently been in a risk situation should therefore watch out for relevant symptoms. In addition to loss of appetite, bloating and indigestion with diarrhea, this also includes inflammation of the gallbladder and liver. Sometimes jaundice also develops, which can be recognized by the discoloration of the eyes and skin. Anyone who shows such signs should urgently consult a doctor.

The Chinese liver fluke is mainly found in East Asia. The suction worm usually gets into the human body through the consumption of raw or incompletely cooked fish. Transmission through contaminated drinking water is also possible. If the attending physician does not ask about it himself, those affected must explicitly point out the presence of such risk factors.

Treatment & Therapy

An effective therapy of the Chinese liver fluke infestation can combine the treatment of the cause with the treatment of symptoms that can be caused by the clonorchiasis. Fighting the cause of the infection with the Chinese liver fluke is possible, for example, by giving the appropriate worm poisons.

Such worm poisons for combating clonorchiasis include, for example, the active ingredient praziquantel. If deworming was successfully carried out in the presence of Chinese liver fluke, it is usual to check the success of the treatment after approx. 3 weeks.

Symptomatic therapy that can accompany the treatment of the causes of an infection through the clonorchiasis is, for example, the relief of occasionally occurring early symptoms such as bloating, loss of appetite or diarrhea. A diarrhea caused by clonorchiasis can be counteracted by a sufficient supply of fluids and electrolytes; rarely and in the case of very severe diarrhea, this can also be combated with medication.

Outlook & forecast

Treatment for clonorchiasis can be relatively simple and effective so that the disease can be completely limited. There are no particular complaints or complications and the disease progresses positively.

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, subside over time and finally disappear completely. There will be no consequential damage if treatment begins early.

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

Due to the severe diarrhea, the patients are dependent on increased intake of fluids and food in order to compensate for the loss of nutrients. If this does not happen, deficiency symptoms or dehydration can occur. Successful treatment of clonorchiasis does not negatively affect the patient’s life expectancy.


An infestation by Chinese liver fluke can be prevented primarily through careful eating; Freshwater fish should only be consumed when they have been sufficiently cooked (as a rule, heating above 55 ° C leads to the death of possible worm larvae) in order to prevent the clonorchiasis from being absorbed through the food. In addition, hygiene measures can help prevent human excrement, and thus the eggs of the Chinese liver fluke, from getting into freshwater ponds.


After medical therapy for the Chinese liver fluke (clonorchiasis), no follow-up examinations are usually necessary. By treating the disease with medication, the parasite is killed and excreted in the stool. If the drug is taken early and as directed by a doctor, the Chinese liver fluke (clonorchiasis) can be completely eliminated from the body without leaving any sequelae.

If there is no renewed infection with the parasite, the symptoms should have disappeared promptly and a normal rhythm of life should be able to resume. A week of relief for the intestines, in which mainly soups and digestible food is consumed, can help to cleanse the gastrointestinal tract after the illness and to make you fit. Bacteria that are involved in the rebuilding of a healthy intestinal flora can be purchased in the pharmacy.

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

It is therefore advisable to consult a doctor at an early stage in the event of gastrointestinal complaints that occur after traveling to other countries or as a result of consuming unfamiliar food. In this way, damage caused by the Chinese liver fluke (clonorchiasis) can be prevented and there is no need for a comprehensive follow-up treatment.

You can do that yourself

The Chinese liver fluke is a parasite that, despite its name, predominantly affects the bile ducts. Although those affected do not develop severe symptoms straight away, clonorchiasis should be taken very seriously and prompt medical treatment.

An important contribution to self-help is therefore to identify the parasite infestation as such as early as possible. The parasite occurs primarily in Southeast Asia, where around 40 million people are infected. Anyone who notices certain symptoms after a business or holiday trip to this region should seek medical treatment promptly and explicitly inform the attending physician about the long-haul trip.

The first signs of clonorchiasis include loss of appetite, bloating, and diarrhea. In the next stage, inflammation of the gallbladder often occurs, which is accompanied by severe pain in the right upper abdomen, and inflammation of the liver. A person affected should not let it get that far, but immediately consult a doctor at the first signs of digestive problems after a long-haul trip.

In addition, the patient can help prevent becoming infected in the first place. The greatest risk is from eating raw freshwater fish. Travelers should therefore make sure that they only consume fish dishes that have been properly cooked or fried or, far better, completely refrain from consuming fish. This also applies to accompanying pets such as dogs or cats, which can also be attacked by the worm.

Chinese Liver Fluke