Clonorchiasis: Causes, Transmission Routes And Treatment Methods

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Clonorchiasis: Causes, Transmission Routes And Treatment Methods
Clonorchiasis: Causes, Transmission Routes And Treatment Methods

Video: Clonorchiasis: Causes, Transmission Routes And Treatment Methods

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Video: Routes of Viral Transmission 2023, February

Clonorchiasis is a parasitic disease caused by helminths of the genus trematodes, characterized by allergic reactions, damage to the liver and pancreas. Clonorchiasis is widespread throughout the world, since people of any age are susceptible to it. However, in the countries of the Far East, the incidence reaches 80% among the entire population. The disease is especially widespread in Korea, Japan, China, Thailand, Laos, Vietnam, the Amur basin and Primorye.


Timely treatment of clonorchiasis leads to a complete cure and has a favorable prognosis. However, the advanced chronic stage of clonorchiasis can lead to irreversible consequences that significantly worsen the patient's condition and quality of life.


  1. Clonorchiasis - description of the disease
  2. Pathogenesis
  3. Symptoms
  4. Clonarchosis treatment
  5. Treatment
  6. Prevention

Clonorchiasis - description of the disease

The causative agent of this disease is the Chinese fluke (Clonorchis sinensis) from the Opisthorchidae family. This parasite has a flat body 20 mm long and 4 mm wide. At the front end of the body is the oral sucker, and just below the abdominal sucker. The eggs of the Chinese fluke are yellowish brown in color and small in size. Adult specimens of the Chinese fluke parasitize humans and mammals, which are their ultimate hosts. For its development, the parasite needs two intermediate hosts: freshwater mollusks and fish of the carp family.

The Chinese fluke can live in the body of the final host for up to 40 years, which explains the long chronic infection throughout life.

Sources of infection are sick people, domestic dogs and cats, as well as wild animals (badgers, muskrats, martens, minks). Eggs excreted by adults are deposited in the bile ducts of the final hosts, penetrate into the intestines, and are excreted with feces. Then the feces with the eggs of the parasites enter a freshwater reservoir, where they turn into larvae and are swallowed by mollusks or crustaceans. They are the first intermediate hosts.

In the body of the mollusk, the larvae undergo asexual reproduction, turning into the next type of larvae - cercariae. Released into the water, cercariae freely swim there in anticipation of another victim (the second intermediate host) - a freshwater fish of the carp family. Once in the skin of freshwater fish, the cercariae are encystised in its muscle tissue and turn into metacercariae (an invasive form of the Chinese fluke). When eating raw or poorly cooked fish, the parasite enters the human body, where it further matures.

Freshwater fish are:

  • crucian carp;
  • bream;
  • carp;
  • vobla;
  • White amur;
  • roach;
  • carp.

Also, the larvae are able to live in crayfish and crabs.

As a result of the action of gastric enzymes, metacercariae are released from the cysts into the duodenum and penetrate into the bile ducts, where they become sexually mature individuals within one month.


Since the Chinese fluke, like all other liver flukes, are hermaphrodites, they produce eggs immediately with embryos without mating. The spread of infection is strictly limited to endemic areas, which reflect the geographical distribution of the main species of snails and crustaceans.


When it enters the intestines of the main host, the cyst of the Chinese fluke dissolves, releasing the larva. The freed larva migrates into the bile ducts from the duodenum, as well as into the pancreatic ducts, liver, gallbladder, where it matures to an adult. The result of the spread of larvae throughout the body and the release of waste products by them is a toxic-allergic reaction, which manifests itself at an early stage of the disease.

There is a relationship between the rate of egg production and feces. At the initial early stage of the development of the disease, a strong inflammatory process develops in the bile ducts, which is accompanied by the formation of thick bile with mucus. In this case, the number of parasite eggs in the feces is quite insignificant. In the chronic stages of clonorchiasis, an increased synthesis of collagen occurs, which leads to fibrosis, to a violation of lipid metabolism and the synthesis of bile acids, which leads to the formation of cholesterol gallstones.


The clinical picture of clonorchiasis has the following stages of the disease:

  • acute early stage;
  • subacute stage (with erased symptoms, asymptomatic, with or without eosinophilia);
  • chronic stage.

The incubation period lasts 14-21 days from the moment of infection until the first symptoms.

The acute early stage is characterized by an acute onset with high fever, pain in the right hypochondrium. The temperature rises chaotically, at any time of the day. A generalized rash appears on the skin in the form of urticaria, significant yellowness of the sclera of the eyes and skin. In the blood, there is an increased level of leukocytes, eosinophils, acceleration of ROE (erythrocyte sedimentation reaction).

The subacute phase, as a rule, proceeds without clinical symptoms. However, nonspecific complaints are possible: general weakness, disturbance in the work of the digestive system, heaviness in the right side. Eosinophilia is observed in the blood formula (up to 20%).

The chronic stage is a consequence of the acute stage, most often, it is primarily chronic in nature. Even in this case, the disease is practically asymptomatic, since only 80% of patients present with complaints. Only in some cases do they complain of a lack of appetite, pain and heaviness after eating in the liver and pancreas. This form of the disease is detected by chance during a visit to a doctor for other reasons, or during medical examinations.

The chronic form of clonorchiasis is complicated by chronic cholecystitis, cholangitis, pancreatitis with the formation of fibrous foci.


Clonarchosis treatment

The disease is diagnosed using the following studies:

  • general blood analysis;
  • general urine analysis;
  • biochemical blood test (protein and its fractions, bilirubin, transaminases, alkaline phosphatase, amylase, trypsin, blood sugar);
  • cholecystography;
  • instrumental methods: ultrasound of internal organs (gallbladder, pancreas, liver);
  • fibrogastroduodenoscopy;
  • study of duodenal juice;
  • serological tests: RNGA (reaction of indirect hemagglutination), RID (reaction of immunodiffusion).

The diagnosis is confirmed in the following cases:

  • the development of clinical symptoms (complaints of patients for the acute and chronic period);
  • epidemiological history (consumption of river fish for food);
  • laboratory research;
  • feces analysis (coproovoscopy).


Treatment is carried out in two ways:

  • etiotropic;
  • symptomatic.

Etiotropic treatment is aimed at eliminating the direct cause of the disease. The main methods of treatment are the latest generation of anthelmintic drugs. Chloxyl (hexachloroparaxylene) is especially effective for clonarchosis. Treatment with this antiparasitic agent is carried out at the beginning of the chronic phase. The applied dose is 0.2 - 0.3 g per 1 kilogram of body weight, the maximum daily dose is 20 - 24 g. Chloxilum treatment is carried out according to three schemes:

  • a three-day course of treatment - carried out with massive parasite infestation in endemic foci;
  • a five-day course of treatment is the most common treatment regimen;
  • a ten-day course of treatment is carried out with poor drug tolerance.

The daily dose of the drug is divided into three doses. Each portion of the medicine is dissolved in half a glass of milk and taken after breakfast, every ten minutes.

For the prevention of clonorchiasis, the drug is taken three days in a row, taking into account 0.1 g per kilogram of body weight.

Also, for the purpose of prophylaxis, praziquantel is prescribed in a daily dose of 50 - 75 g per kilogram of body weight, three times a day, pre-dividing the dose into 3 parts. The course of treatment is one day.

Symptomatic treatment consists in taking the following funds:

  • non-steroidal anti-inflammatory drugs (ibuprofen);
  • antihistamines (suprastin);
  • blockage of the proton pump for stomach pain (pantoprazole);
  • enzymes (mezim);
  • sorbents (polysorb);
  • antispasmodics (no-shpa);
  • antibiotics (for bacterial infection);
  • choleretic drugs (rose hips, corn silk);
  • hepatoprotectors (Ursokhol, Essentiale).

Clonorchiasis is treated in several stages according to the following scheme:

  • preparatory;
  • antiparasitic;
  • restorative.

The preparatory stage involves the solution of the following tasks:

  • cleansing the body of toxic elements;
  • restoration of biliary function;
  • diet therapy.

The diet for this helminthiasis, called clonorchiasis, includes restricting the use of fatty, spicy and fried foods. Soups with vegetable broths, boiled vegetables, cereals, dairy products, boiled eggs, lean meat and fish, white bread are welcome. The use of foods rich in proteins, carbohydrates, vitamins and minerals is encouraged.

Boiled soups in second broths, boiled vegetables, dairy products, cereals, boiled eggs, meat, low-fat fish, white bread.

At the same time, they take drugs that contribute to better digestibility of food: probiotics, choleretic agents, laxatives, enzymes, hepatoprotectors.

The antiparasitic stage involves treatment with anthelmintic drugs to destroy helminths. For this purpose, the following antihelminthic drugs are prescribed:

  • biltricide (praziquantel);
  • chloxyl.

The recovery stage is aimed at restoring impaired body functions and normalizing the excretory functions of the intestines. During this period, probiotics, choleretic agents, laxatives, hepatoprotectors, antispasmodics, enterosorbents are prescribed.

After a successful recovery, patients are registered with an infectious disease doctor for another six months. During this period, repeated tests for clonorchiasis are regularly performed. Negative test results allow patients to be removed from the register.



To avoid infection with Chinese fluke, first of all, it is necessary to subject the fish to high-quality heat treatment.

You need to cook the fish for at least 20 minutes, only in this case the metacercariae die in its body. You need to fry the fish for 15–20 minutes on one side only. It should be remembered that metacercariae retain their viability in salted, smoked and dried fish. Hot smoked fish qualitatively disinfects. Correct salting of fish allows you to destroy the helminths in it. It is not worth freezing the fish, since the metacercariae retain their viability for a month.

Cutting fish should be done on a separate cutting board with a special knife. Personal hygiene, especially after fish handling, is an important condition in preventing the development of clonorchiasis infection.

Also, an important role in the prevention of clonarchosis is played by sanitary and educational work and the protection of freshwater from contamination with faeces.

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