Trematodes Are: Types, Symptoms And Treatment In Humans

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Trematodes Are: Types, Symptoms And Treatment In Humans
Trematodes Are: Types, Symptoms And Treatment In Humans

Video: Trematodes Are: Types, Symptoms And Treatment In Humans

Отличия серверных жестких дисков от десктопных
Video: Helminths: Cestodes and Trematodes (transmission, clinical importance, and treatment) 2023, February

Trematodes belong to the class of flatworms. These parasites, also called digenetic flukes, cause trematodes in humans. Most often, the human body is affected by hepatic, pulmonary, and blood flukes. The life cycle of these helminths is characterized by the development of the worm in the body of an intermediate and final host.


  • 1 General characteristics of parasites
  • 2 Life cycle
  • 3 Classification of trematodes affecting humans

    • 3.1 Schistosomes
    • 3.2 Other trematodes
  • 4 General symptoms of trematodosis
  • 5 Treatment

General characteristics of parasites

A pair of suckers is located on the body of the trematodes, one of them is localized in the oral cavity, and the other in the peritoneal region. Cuticular spines are located on the upper layer of the epithelium, which are necessary to strengthen the parasitic individual in the host's body.

These worms can grow from 2 millimeters to 1.5 meters in length. Worms can grow to large sizes in the body of livestock, fish, and humans. They are mostly leaf-shaped or round. Schistosomes differ in shape, which are characterized by an oval or elongated body.

On the basis of their habitat, they are conventionally divided into 4 groups:

  • affecting the liver;
  • localized in the lungs;
  • blood;
  • leading their life in the small intestine.

All flukes have a similar development cycle.

Life cycle

The life cycle of trematodes is as follows:

  1. Sexually mature parasites multiply and lay eggs in the final organism. They enter the environment together with feces, urine or sputum. In the egg of the trematodes, the miradiation matures - the first stage of the larva. Miraditsii - some types of parasites after hatching, capable of moving independently with the help of cilia. The rest are immobile, so they are only swallowed by their intermediate host;
  2. Further, miraditsii settle in the organism of the intermediate host. In almost all parasites of this class, the mollusk is the first host. Once inside its body, the larva begins to develop up to its second mobile stage - sporocysts. Sporocysts are endowed with the ability for parthenogenesis, which allows them to reproduce without fertilization;
  3. Further, the larva develops up to stage 3 - redia, which also retains the ability to parthenogenesis. Next, cercariae begins to form - the last larval stage;
  4. the cercarium is similar in structure to an adult. They are characterized by the presence of a tail, suckers, rudiments of the digestive system, as well as excretory and reproductive systems. In this state, they leave the body of the intermediate host using a thorn. Depending on the parasitic species of trematodes, cecarii settle in the bodies of the intermediate or main host, or die;
  5. At the cercaria stage, most trematodes are able to penetrate the host's epidermis, while other species form a spore, clinging to grass, and wait for ingestion by fish, livestock, or humans. Having settled in the body of the final host, an adolescarium is formed from the larva, the ingress of which into the body begins to provoke the development of diseases. Gradually, the parasite forms into a sexually mature individual called a marita.

Classification of trematodes affecting humans

Most often, the human body is affected by flukes, localized in the liver and lungs, as well as blood parasites.


Only 12 types of trematodes are dangerous for people, since they are pathogens of pathologies of varying degrees. Human trematodes are divided into 2 groups.


Schistosoma is a blood fluke that conducts its vital activity in the circulatory system of the main host. This type of parasite is widespread in countries with a warm climate. People become infected with schistosomiasis when swimming in polluted waters.

Schistosomes are dioecious parasites. It is interesting that the female until the end of her existence is in the fold of the male, which allows them to regularly give birth to offspring. The body of schistosomes is long and thin, it can grow in length up to 10-30 millimeters, having a diameter of 0.2-1 millimeters. Sexually mature males are characterized by a thicker and shorter body, equipped with a long fold.

The following types of schistosomes can affect the human body:

  • Mansoni;
  • hematobium;
  • Japanese;
  • intercalatum.

Schistosoma Mansoni can be infected in the Middle East, the African continent, South America, the Caribbean. Hematobium is common in Africa and the Middle East. The Japanese schistosoma is found in China, East Asia, and the Philippines. Intercalatum is localized exclusively on the territory of the African continent.

Other trematodes

Most species of these parasites are localized in the human gastrointestinal region. There they lay eggs, which enter the external environment along with feces.

Among the main flukes, not related to schistosomes, there are:

  • fasciolopsis Buski, the source of which are plants contaminated with helminth eggs. This worm mainly spreads in Asia and India;
  • heterophiasis - can be infected in Asia, Eastern Europe, the Middle East, and also in Egypt. The carriers are fish;
  • metagonimus Yokogawa - widespread in Siberia, trout and carp are its carriers;
  • Gominus gastrodiscoidosis - can be infected in India, Vietnam, the Philippines through the consumption of contaminated plants;
  • the Chinese fluke is widespread in East Asia, as well as in North America, its main carriers are fish;
  • hepatic fluke is common all over the world, it affects humans when they eat plants on which the parasite larvae are attached;
  • the paragonimus Westermani infects people in Asia and is carried by freshwater fish or crabs;
  • the cat's fluke is a parasite in Europe, in the Middle East, and infects the human body when eating carp.

General symptoms of trematodosis

Trematodes can cause various symptoms. Symptoms differ depending on the parasitic species and its location in the human body. Doctors identify the following common symptoms of trematodosis:

  • the development of allergic reactions in the form of urticaria and itching sensations;
  • development of bile duct dyskinesia;
  • the appearance of pain in the abdominal region;
  • an increase in the volume of the liver and spleen;
  • regular occurrence of headaches and migraines;
  • development of blood eosinophilia.

Usually, the primary symptoms appear after 3-4 months - after the incubation period. During this time, the helminth reaches a sexually mature state and begins to actively reproduce. It is worth considering that adult worms are capable of mechanically damaging soft tissues, as well as internal organs.

In some cases, trematodes in the human body cause:

  • blockage of the choleretic ducts;
  • development of microabscesses;

the appearance of organ micronecrosis

Pathology in advanced cases is accompanied by thickening of the walls of the bile ducts, adenomatous proliferation of epithelial tissues. Such processes can lead to angiocholitis, atopic cholecystitis.


Treatment for a trematode depends on the species. The general principles of therapy are to conduct:

  • pathogenetic treatment;
  • anthelminthic treatment;
  • therapy that improves immunity.

The symptoms of intoxication are eliminated with the help of pathogenetic therapy. Also, in the complex of such measures, it is necessary to take antihistamines. If the digestive system was affected, then a diet, hepatoprotectors, choleretic medicines are prescribed during this period.

Of the antihelminthic medicines, the following are commonly used:

  • Praziquantel - for the treatment of schistosomiasis, clonorchiasis, paragonimiasis, opisthorchiasis;
  • Triclabendazole, Albendazole - for the treatment of hepatic, giant fluke;
  • intestinal schistosomiasis is treated with Oxamnihin;
  • genitourinary schistosomiasis - Metriphonate.

If a person has symptoms of trematodosis, then he should consult a doctor as soon as possible, and then begin the prescribed treatment. This is due to the fact that this pathology is treated faster and more efficiently at the initial stage.

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