A Chinese liver fluke is a parasite that can cause a worm disease called clonorchiasis in humans. Symptoms do not always indicate this.
What is a Chinese liver fluke?
A Chinese liver fluke (clonorchiasis) is one of the sucking worms and occurs mainly in the areas of South and East Asia. However, related species of the parasite clonorchiasis can be found beyond Asia to Eastern Europe. Clonorchiasis infects humans and mammals that feed on freshwater fish as definitive hosts. The clonorchiasis resides in the liver and bile ducts 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 human is infested with clonorchiasis, this is also referred to as clonorchiosis. This worm disease caused by clonorchiasis is one of the three most common diseases caused by worms worldwide. According to World Health Organization (WHO) estimates, Chinese liver fluke occurs in up to 30 million people worldwide.
Causes
Infection with clonorchiasis occurs primarily from eating uncooked or raw carp-like freshwater fish. A Chinese liver fluke resides in the muscle and skin of the intermediate host fish. If a person becomes infected with the clonorchiasis, it enters the small intestine; from here, larvae of the clonorchiasis move on to the liver and bile ducts. Once in the bile ducts, the larvae of clonorchiasis develop into adult parasites. Eggs of adult Chinese liver fluke are excreted in human feces and can re-enter the freshwater cycle. If these eggs Chinese liver fluke are ingested by freshwater snails, the clonorchiasis migrates in various stages of development from freshwater snail to freshwater fish and finally to the appropriate final host.
Symptoms, complaints, and signs
Clonorchiasis is always associated with discomfort in the abdomen and stomach. These complaints are very unpleasant and can significantly complicate the daily life of the affected person. First and foremost, there is discomfort in the bile ducts. 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 occur even without food intake. Furthermore, most patients suffer from permanent diarrhea, so that [[dehydration]9 and various deficiency symptoms may occur if the losses are not compensated. In the further course, bile stasis occurs if clonorchiasis is not treated. In severe cases, the gallbladder must be completely removed. However, the infection can spread to the other parts of the body and infect other internal organs as well. This can cause problems with the liver or even the kidneys. In the worst case, the affected person dies of liver failure or kidney failure. Clonorchiasis can usually be cured well if therapy is started early. Late onset may also result in long-term damage that cannot be treated.
Diagnosis and course
Although symptoms caused by a Chinese liver fluke in humans (such as diarrhea or inflammation of the bile ducts) may indicate infection with clonorchiasis, they are not necessarily caused by the fluke. However, since these symptoms caused by clonorchiasis are very non-specific, a Chinese liver fluke or its eggs must usually be diagnosed by examining a patient’s stool or bile. Clonorchiasis infection can also be detected with the help of secretions from the duodenum of an affected person. The course of an infection with clonorchiasis can vary greatly depending on the patient; frequently, a corresponding infection is asymptomatic. Symptoms often do not appear until a patient is infested with more than 100 specimens of Chinese liver fluke. The incubation period (i.e. the time between infection by the clonorchiasis and the maturation of adult Chinese liver fluke) is about 4 weeks. Possible late effects of Chinese liver fluke infestation include altered tissue structures of the bile. Without appropriate therapy, excretion of Chinese liver fluke eggs by an affected person can last up to 30 years.
Complications
Chinese liver fluke primarily nests in the bile ducts, where it leads to various complications. Affected individuals usually experience loss of appetite, which, combined with the typical diarrhea, can lead to deficiency symptoms, dehydration, and other problems. As a result of gallbladder inflammation, the intestinal wall may rupture, fistulas may form, or gallstones may form. Rarely, jaundice or inflammation of the pancreas also occurs as a consequence, which in turn is associated with severe complications. If the liver fluke is not detected, it sometimes nests in the bile ducts for the rest of its life and lays eggs there again and again. The constant irritation of the bile ducts increases the risk of malignant diseases such as biliary carcinoma or liver cirrhosis. In extreme cases, the liver and spleen enlarge and organ failure occurs. Chronic infestation can also lead to “porcelain gallbladder,” in which calcium deposits form in the gallbladder wall and can cause carcinoma and gallstones. If Chinese liver fluke is detected and treated early, severe complications rarely occur. However, commonly used agents such as albendazole can cause side effects such as anemia, rash, and itching.
When should you see a doctor?
If infection with Chinese liver fluke is suspected, a doctor should be consulted immediately. While there is no acute danger for most affected individuals, the sooner the parasite is destroyed, the lower the risks for long-term damage, which can include serious complications such as pancreatitis, cirrhosis of the liver, or bile duct carcinoma. Patients who are or have recently been in a high-risk situation should therefore pay attention to relevant symptoms. These include loss of appetite, bloating and indigestion with diarrhea, as well as gallbladder inflammation and liver inflammation. Sometimes jaundice also develops, which can be recognized by the discoloration of the eyes and skin. Anyone showing such signs should urgently consult a doctor. The Chinese liver fluke is mainly distributed in East Asia. The sucking worm usually enters the human body by eating raw or undercooked fish. Transmission through contaminated drinking water is also possible. If the attending physician does not ask about this on his or her own, affected individuals must explicitly point out the presence of such risk factors.
Treatment and therapy
Effective therapy for Chinese liver fluke infestation can combine cause treatment with treatment of symptoms that may be caused by clonorchiasis. Cause control of Chinese liver fluke infection is possible, for example, by administering appropriate worm poisons. Such worm poisons to combat clonorchiasis include, for example, the active ingredient praziquantel. If deworming has been successfully carried out in the presence of Chinese liver fluke, it is usual to check the success of treatment after about 3 weeks. A symptomatic therapy, which can accompany the treatment of the causes of an infection by the clonorchiasis, lies approximately in the relief of occasionally occurring early symptoms such as bloating, loss of appetite or diarrhea. Diarrhea caused by clonorchiasis can be countered, for example, by adequate intake of fluids and electrolytes; rarely and in cases of very severe diarrhea, it can also be treated with medication.
Outlook and prognosis
Relatively simple and effective treatment can be given for clonorchiasis, so that the disease can be completely limited. No particular symptoms or complications occur, and there is a positive course of the disease. The treatment of clonorchiasis is carried out 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 eventually disappear completely. There are no consequential damages if the treatment is started early. If clonorchiasis is not treated, it can cause serious illness in the patient’s stomach and intestines, which in the worst case can lead to death. However, death from clonorchiasis is relatively rare and occurs only when symptoms are completely ignored.Due to the severe diarrhea, patients are dependent on an increased intake of fluids and food to make up for the loss of nutrients. Failure to do so may result in deficiency symptoms or dehydration. If clonorchiasis is successfully treated, the patient’s life expectancy is not negatively affected.
Prevention
Prevention of infestation by Chinese liver fluke can be achieved primarily by mindful food intake; freshwater fish should be consumed only in a sufficiently cooked state (usually heating above 55°C results in the death of any worm larvae) to avoid ingestion of clonorchiasis through food. In addition, hygiene measures can help prevent human excreta, and thus eggs of the Chinese liver fluke, from entering freshwater ponds.
Follow-up
After medical therapy for Chinese liver fluke (clonorchiasis)follow-up is usually not necessary. Medical treatment of the disease kills the parasite and excretes it in the stool. If the medication is taken early and according to the doctor’s instructions, the Chinese liver fluke (clonorchiasis) can thus be completely eliminated from the body without leaving any after-effects. If no new infection with the parasite occurs, the symptoms should disappear promptly and a normal rhythm of life can be resumed. A relief week for the intestines, in which mainly soups and light digestible food is consumed, can help to cleanse the gastrointestinal tract after the disease and make it fit again. Bacteria involved in the reconstruction of healthy intestinal flora can be purchased at the pharmacy. If the parasite infestation persists over a long period of time, possibly even for years, without being detected, secondary diseases of the internal organs can develop. Any damage to the pancreas, bile ducts, liver and spleen must then be treated separately. Inflammations and malignant changes such as bile carcinomas require more extensive medical treatment and are accompanied by severe symptoms. It is therefore advisable to consult a doctor at an early stage in the event of complaints in the gastrointestinal tract that occur after traveling to other countries or as a result of consuming unfamiliar food. In this way, subsequent damage caused by Chinese liver fluke (clonorchiasis)can be prevented and extensive follow-up treatment can be omitted.
What you can do yourself
Chinese liver fluke is a parasite that, despite its name, primarily affects the bile ducts. Although those affected do not immediately develop severe symptoms, clonorchiasis is very serious and should definitely be treated promptly by a doctor. An important contribution to self-help is therefore to identify the parasite infestation as such as early as possible. The parasite occurs predominantly in Southeast Asia, where around 40 million people are affected. Anyone who notices certain symptoms after a business or vacation trip to this region should seek medical treatment promptly and explicitly inform the attending physician about the long-distance trip. The first signs of clonorchiasis include loss of appetite, bloating and diarrhea. The next stage often involves inflammation of the gallbladder, accompanied by severe pain in the right upper abdomen, and inflammation of the liver. However, a person affected should not let it get that far, but should immediately consult a doctor at the first signs of digestive problems after a long-distance trip. In addition, the patient can help to prevent infection in the first place. The greatest risk lies in eating raw freshwater fish. Travelers should therefore make sure that they only consume fish dishes that are properly cooked or fried or, far better, avoid eating fish altogether. This also applies to accompanying pets such as dogs or cats, which can also be infected by the worm.
