Clonorchs: Appearance, Eggs, Structure And Infection Routes

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Clonorchs: Appearance, Eggs, Structure And Infection Routes
Clonorchs: Appearance, Eggs, Structure And Infection Routes

Video: Clonorchs: Appearance, Eggs, Structure And Infection Routes

Отличия серверных жестких дисков от десктопных
Video: Clonorchis sinensis Eggs 2023, February

Page content

  • Clonorchiasis causes
  • Pathogen life cycle
  • What fish can you get infected with?

    • Light form
    • Moderate form
    • Severe form
    • Complications
  • Diagnostics
  • Clonorchiasis treatment

    • Drug therapy
    • ethnoscience
  • Forecast and prevention
  • You can defeat parasites!

Clonorchiasis is a trematodosis, that is, an infection caused by flukes. The first description of the helminth was made by the English researcher McConnell in 1874, later the pathogen was studied in detail by the Japanese scientist Kobayashi. The greatest prevalence of clonorchiasis is noted in Southeast Asia (most cases were recorded in China, Korea and Japan), Amur Region, Primorsky Territory.

Today, due to labor migration, economic cooperation, globalization, helminthiasis is becoming a problem of worldwide infectious diseases. More often men over 35 are infected, there is no clear seasonality.

What to do in such a situation? To get started, we recommend reading this article. This article details the methods of dealing with parasites. We also recommend contacting a specialist. Read the article >>>

Clonorchiasis causes

The causative agent of helminthiasis is the trematode Clonorchis sinensis, Chinese fluke. Sources of infection are humans and mammals, the route of transmission is alimentary. Adult C. sinensis worms usually live in the bile ducts of their final hosts, and eggs are excreted in the faeces.

Chinese fluke: structure
Chinese fluke: structure

Freshwater snails can serve as the first intermediate hosts. Eggs in water develop into miracidia, and after being swallowed by snails, into sporocysts, redia and cercariae. Mature cercariae swim freely in the water, invade the second intermediate hosts (freshwater fish) through the skin, and then form metacercariae in the muscles of the fish.

The main risk factors for clonorchiasis are work in public catering establishments, fisheries and farms, poor organization of social conditions, and low incomes of the population.

The incidence of metacercariae in fish in different regions varies from 7 to 102 freshwater species. One of the properties of helminths is long-term (up to 40 years) persistence in the body without treatment, as well as a connection with the formation of fibrosis and malignant transformations of hepatocytes, tissue of the biliary ducts. The incidence of disability after undergoing nosology correlates with the severity of symptoms.

The mechanisms of the pathological effect of clonorchs are not fully understood. Helminth causes periductal fibroplasia, starting from the 7th day of illness, activates lipid peroxidation, which is accompanied by damage to the DNA of the cells of the hepatobiliary apparatus. Hepatocytes undergo hydropic degeneration, the apoptosis of abnormal cells is suppressed, which promotes tumor growth. The maintenance of chronic inflammation leads to fibrotic tissue changes and the formation of carcinomas.

Many patients with symptoms of this helminthiasis have high levels of IL-33 / ST2, a powerful inducer of epithelial cell proliferation and fibrosis. The parasite-induced production of IL-13 and IL-10 avoids the effects of the immune system due to their pronounced anti-inflammatory effect; another effect of these interleukins is the induction of collagen formation in tissues. In the cells of the biliary epithelium, there is an excessive production of TNF-alpha and gamma-interferons, which support chronic inflammation.

Chinese fluke
Chinese fluke

Pathogen life cycle

The ultimate hosts of Clonorchis sinensis are humans, dogs, pigs, cats, martens, badgers, minks, ferrets, and rats. Eggs produced by adult worms are deposited in the bile ducts of these mammalian hosts, enter the intestines, and are excreted in the feces. After entering the water, the eggs are swallowed by snails, which serve as the first intermediate hosts.

In snails, the larvae undergo metamorphosis and asexual reproduction for 4 to 5 weeks, after which the cercariae return to the water. These free-swimming forms penetrate the skin of freshwater fish. Numerous freshwater fish species, mainly belonging to the cyprinid family, serve as a second intermediate host. After a few days, cercariae in the muscle tissue of fish transform into the form of metacercariae. Humans and other fish-eating mammals then become infected with them by ingesting raw or undercooked fish.

As a result of digestion processes in the stomach and intestines, metacercariae leave the cysts in the duodenum and migrate into the bile duct, where they mature into adult worms within one month.

The adult worm is a small elliptical trematode with an average length of 10 to 25 mm. Chinese flukes, like all other liver flukes, are true hermaphrodites and lay eggs immediately with embryos without mating.

Adult worms remain viable for 20 to 25 years, which explains chronic infection for a long time. Completion of this life cycle is limited to endemic areas of infection, which reflect the geographic distribution of the main snail species.

What fish can you get infected with?

More than 100 different species of freshwater fish (crucian carp, grass carp, carp, etc.) act as the second intermediate host for the pathogen of clonorchiasis. The most common of them belong to the carp family. Larvae can also live in freshwater crayfish and crabs.

The clinical manifestations of clonorchiasis are variable and, as a rule, depend on the degree of infection with worms.

Light form

Most patients with a mild relative form of infections, i.e. with fewer than 100 flukes, several symptoms appear. Early symptoms may include general malaise, abdominal discomfort, and diarrhea. In 10-40% of patients, peripheral eosinophilia (an increase in the number of eosinophils in the blood) is accompanied by wavelike jaundice.

Moderate form

Moderate infection (usually fewer than 1000 parasites in the body) presents with fever and chills, as well as fatigue, lack of appetite, diarrhea, weight loss, discomfort, and bloating.

Severe form

Up to 20,000 fluke can be present in patients with severe disease that presents with acute right upper quadrant pain, often superimposed on signs and symptoms that occur with moderate infections. In the late stage of severe infections, jaundice, diarrhea, portal hypertension (increased pressure in the vein approaching the liver), hepatosplenomegaly (enlarged spleen and liver), and edema may occur.


Purulent cholangitis, cholelithiasis, chronic cholecystitis, pancreatitis, and cholangiocarcinoma have been described as potential long-term complications of clonorchiasis. Many hepatic and biliary diseases can resemble clonorchiasis in their clinical manifestations.


Clonorchiasis is suspected in patients presenting with symptoms of liver disease or gallstone disease if they have had a history of eating raw freshwater fish in endemic areas.

Analysis of feces for eggs, worms and protozoa
Analysis of feces for eggs, worms and protozoa

The diagnosis of clonorchiasis is usually established by microscopic examination of feces for helminth eggs. Serological tests are used to examine the contents of the duodenum and stool to detect eggs.

Currently, clonorchiasis is often diagnosed accidentally during X-ray examination, ultrasound and other imaging of the abdominal organs for other purposes, since the symptoms of clonorchiasis are vague and nonspecific in most cases.

Treatment options for clonorchiasis include:

  • The World Health Organization (WHO) recommends the use of the anthelmintic drug Praziquantel for infected individuals. It can be prescribed to people as a preventive measure - people who show no signs of the disease, but live in endemic regions. The treatment regimen is 25 mg / kg of body weight 3 times a day for 1 day.
  • surgery may be required if the bile duct is still blocked despite praziquantel treatment to remove the worms.
  • treatment of complications, if necessary, is carried out with the use of intravenous antibiotics or with surgery.

Clonorchiasis treatment

Severe forms of the disease are subject to serious treatments. So in some cases, they resort to surgical intervention. It is needed when a parasite colony clogs up the bile ducts. Sometimes a course of intravenous antibiotics may be prescribed. But still, such methods of treatment are used extremely rarely. In most cases, it is sufficient to use available medicines.

Drug therapy

The World Health Organization recommends the use of Praziquantel. The daily rate is calculated based on the patient's weight and is 25 mg / kg. The medicine is taken three times a day, and the entire course ends on the first day. In regions with frequent outbreaks of clonorchiasis, it is recommended to use this agent for prevention.

To cure an adult with a chronic stage of the disease, medications such as "Chloxil" and "Hexachloroparaxylene" are used. The dose is calculated on the basis that 0.2-0.3 grams should fall on one kg of weight, but not pain 24 g per day. The daily dose is divided into three doses. The medicine must be mixed with milk and drunk 10 minutes before meals. The course of therapy lasts from three to ten days, it all depends on the body's response to the drug and the number of parasites.


Some people recommend using folk remedies to treat clonorchiasis. Tar is considered one of the most popular remedies. It is melted to a liquid form and dissolved in a teaspoon of milk. On the first day, it is allowed to drink only two drops of the medicine. Then every day the dosage is increased by two drops until it reaches 10. Next, there is a countdown. This method is designed for adults and children over 10 years old.

For a mild form of clonorchiasis, medicinal plants can be used. The following options will work:

A tablespoon of the selected ingredient must be steamed in a glass of water and drunk throughout the day. If desired, it is allowed to mix all medicinal plants at the same time

It is still best to try to avoid this disease. To prevent the disease, it is necessary to use different knives for cutting fish and other products. Conduct sufficient heat treatment (either fry at temperatures above 63 °, or freeze for a week at -20 °). It is also important to always wash your hands thoroughly after handling fish.

Forecast and prevention

The disease has favorable prognosis in the absence of complications and timely treatment started. Clonorchiasis is completely curable.

Preventive measures include adherence to the following recommendations:

  • Timely diagnosis and treatment of pathology;
  • Eating well-processed freshwater fish and crayfish
  • Use of separate kitchen utensils for cutting fish;
  • Compliance with sanitation and hygiene;
  • Conducting the protection of reservoirs from fecal contamination;
  • Conducting educational work among the population in epidemiological areas;

Particular attention should be paid to preventive measures when visiting Asian countries for the first time. In this case, the incidence of the local population can sometimes reach 100%.

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