Hepatic fluke: structure, pathways of infection, stages of development, prevention

A dangerous parasite that affects the liver and causes fascioliasis is the hepatic trematode. Consider its life cycle, ways of infection and methods of destruction.

Helminth refers to the parasitic form of flukes that inhabit the organs of vertebrates (animals, humans) and invertebrates. Another name for the parasite is the cat's fluke, since the cat is the most suitable host for the worm. An adult detects a person and cattle. The fluke has a leaf-shaped body and reaches a size of 3-5 cm. It can enter the organs of herbivores and fish, which act as a secondary host.

The main characteristics of the parasite:

• On the body is a special veil, protecting it from digesting the host's juices.
• A lot of fastening elements: hooks, suckers and more.
• Simple structure of the digestive system.
• High fecundity and asexual reproduction.
• Regressive development of the sense organs and the nervous system.

The parasite is characterized by a complex life cycle with transformations and a frequent change of hosts. This leads to its resettlement and protects the main carrier from excessive overpopulation and death. Most often, human infection occurs when you use unboiled or unrefined water.

[1], [2], [3], [4], [5],

Structure of the hepatic trematode

The main difference between a flat worm and other parasites is its complex structure. The structure of the liver flukes is represented by such organs and systems:

• The leaf form is 3-5 cm, flattened in the dorso-ventral direction.
• Developed fastening organs: oral and abdominal suckers with oral opening.
• Branched digestive system and absence of anus.
• Protonephridial excretory system.
• Undeveloped respiratory and circulatory system.
• Asexual reproduction and development with the change of carriers.
• Developed nervous system (okolglotochechnoe nerve ring, nerve strands along the body).

The cycle of helminth development passes with constant transformations. Each stage of development has its own structure.

Internal structure of the liver fluke

In humans, the fascioliasis can be both fasciola vulgaris and giant. Both have a specific and almost identical structure and functioning, which is due to their parasitic way of life. Consider the internal structure of the hepatic trematode:

• Oral sucker.
• Pharynx.
• Brain.
• Nerve ring.
• Esophagus.
• Abdominal sucker.
• The main branch of the intestine.
• Shellfish glands.
• Abdominal neural trunk.
• Uterus.
• Ovary.
• Testis.
• Swallow commissure.
• Vitellaria.

The parasite has a leaf-shaped body, 2-7 cm in size and grayish-yellow in color. It lives in the bile ducts, liver and pancreas of vertebrates. With the help of the oral and abdominal suckers fastened and held on the walls of the ducts.

The basic systems of vital activity of the worm:

1. Digestive - the oral opening is connected to a muscular pharynx (sucking apparatus). Behind the pharynx there is a branched esophagus and blindly terminating intestines.
2. Nervous - is an oclo-pharyngeal nerve ring, from which three pairs of nerve trunks leave (lateral ones are most developed). Nerve trunks are connected by means of jumpers, which makes them look like a lattice.
3. Excretory - developed protonephridia in the depth of the parenchyma. Thermal cells have channels with cilia, which select tissue tissue from the parenchyma and dissimilation products. Cilia propel the fluid through the canals and excretory pores, removing from the body.
4. Sexual - helminth is a hermaphrodite. The male reproductive system consists of a pair of testes, two vas deferens that merge into the ejaculatory duct and cirrus. The female reproductive system is more complicated: the ovary, the vitellaria, the spermatheca, the ootype (in it fertilization and the formation of eggs take place), the uterus and the genital orifice. In some species, fertilization occurs in the seminal receptacle. In most cases, insemination is cross, but there are also cases of self-seeding.

The fluke is characterized by simplification and specialization in the structure of some organs. This is due to her parasitic way of life. As a specialization, suckers, thorns and other formations on the body of the worm, powerfully developed sexual organs and several complex life cycles act. Morphological simplification is expressed by the absence of sense organs in sexually mature individuals, which act as endoparasites.

[6], [7], [8], [9]

Digestive system of the liver fluke

The structure of the digestive system of the baker's flukes is quite developed and consists of:

• Oral sucker.
• Pharynx.
• Abdominal sucker.
• Branching intestines.

The digestive tract, branched, and has two departments - front and middle. The anterior one is the pharynx and esophagus lined with ectoderm. The middle one is the endodermal bowel, two-branched, blind-closed. In some representatives of this class, the branches of the midgut have many blind processes. Parasites with a developed intestine have intestinal digestion of food, and helminths with rudimentary digestion absorb the digested food of the host through the tegument (integument of the body).

The parasite feeds on tissues and blood of its carrier with sucking movements of the pharynx. Undigested remains of food get to the outside through the mouth opening. Flat worms that infest fish have an anus, which is represented by a separate intestinal trunk and excretory vesicle.

[10], [11], [12], [13]

Nervous system of the liver trematode

The central nervous system of the hepatic trematode is represented by such departments:

• Ocheloglonic ring.
• Nerve trunks: lateral, ventral.
• Jumpers.

The nervous system is located in the anterior third of the body at the pharyngeal level. It is an oclo-pharyngeal ring, from which three nerve trunks leave. The end sections of the trunks are ramified, and they enter the tegument. From the ganglion ganglion, two ventral, dorsal and lateral trunks extend, which extend to the posterior end of the body and merge, forming an arch. Longitudinal nerve trunks are connected by crosspieces - transverse commissures. Thanks to this, the nervous system resembles a lattice that surrounds the entire body.

Circulatory system of the liver trematode

Flat worms are parenchymatous, that is, are bespokostnymi animals. There is no circulatory system in the liver trematode. The space between its internal organs consists of a mesodermal-type connective tissue or a parenchyma with a multitude of cells. In this case, the parenchyma fills all the gaps between the organs. It serves as a store of nutrients and is responsible for the exchange processes.

The parasite also lacks the respiratory system. Special organs of excretion - protonephridis, are found throughout the body. They represent a system of branching canals that end in the parenchyma in the form of star cells with cilia. With the help of special excretory (excretory) holes protonefridii contact with the external environment.

[14], [15]

External structure of the hepatic trematode

The causative agent of fasciola has a dense body adapted to life in the bile ducts of the carrier. The external structure of the hepatic trematode is a multilayer cuticle that protects against digestion, antitoxins and secretory fluid of the primary host. Through the skin, gas exchange and release of nitrogen-containing substances occurs.

The outer part of the covers is a denuclearized cytoplasmic plate with mitochondria and vacuoles. With the help of cytoplasmic strands, this layer is connected to the areas of the cytoplasm (immersed in the parenchyma), in which the nuclei are located.

Helminth has a leaf-shaped body and can reach a size of 3-5 cm in length, up to 1.5 cm in width. The cephalic end of the body is covered with spinules, has an elongated proboscis, a head and abdominal suckers. Skin without cilia, but with a well developed muscular layer. Due to its structure and parasitic lifestyle, the worm is able to survive with a lack of oxygen.

The organs of fixation of the liver flukes

The adult helminth specimen has a leaf-shaped, flattened shape with a pointed posterior end. The organs of fixation of the liver fluke - suckers and thorns. With their help the parasite is fixed in the bile ducts, liver or pancreas of the host. Such a fixation method protects against flushing with a secretory fluid.

At the anterior (broad) end of the body there is a narrow protrusion with the oral sucker. Sexually mature individuals are well developed organs of fixation, digestive and reproductive systems. Having attached to live tissues, fluke does not change its location. It grows, feeds and lays eggs in the bile ducts. With the current of the bile, the eggs enter the intestine of the carrier and are excreted outward with excrement.

The sensory organs of the hepatic trematode

The causative agent of fasciola has poorly developed sense organs. The liver fluke, or rather its larvae, floating in the water, there are several pairs of small peepholes arranged in the manner of turbellarians. In rare cases, the appendages develop along the sides of the head end, resembling ears. Such growths are considered as sensory organs (tactile and chemical).

Sensils, that is, skin receptors, have an identical structure to the turbellarians, and an advantage is observed in the larval stage of the parasite. The nervous system has a more complex structure. It consists of an oclo-pharyngeal nerve ring, two ganglia and longitudinal nerve strings (innervate the sucker). From the nerve ring leaves 3 pairs of powerful longitudinal nerve trunks with well developed lateral nerves. They branch into numerous processes that run all over the body of the worm.

Organs of movement of the liver fluke

An important feature of the structure of the parasite is the organs of movement. In the hepatic trematode, they are represented by a skin-muscular sac. It consists of an outer cover (tegumen), fused with muscle threads. Actinic spines are located in the cytoplasm of the connecting bridges.

Fluke has an archaic structure of muscle tissue. The muscle cell is represented by the myocyte, from which the processes with contractile fibers depart. In this case, each of the myocytes from 2 to 10 shoots.

Under the solid external syncytial plate are the ring, diagonal and longitudinal muscles. The most pronounced muscular layers are in the locomotor department of the corpuscle corpuscle. The generative department of muscle fibers is smaller and they are disordered.

Egg of the liver fluke

Among the trematodes, the egg of the hepatic trematode is the largest. Its dimensions are 130-150x70-90 microns. Eggs are oval in color, ranging from yellowish to dark brown. Covered by a smooth, dense two-contour shell, on one side of which there is a small lid through which miracidium comes out. At the opposite pole, the shell is thickened and is a tubercle. The core content is fine-grained.

• From the ovary already formed eggs enter the ootype, where they are fertilized. The process of insemination takes place by the introduction of a copulatory organ into the uterus. Spermatozoa penetrate the spermatheca and into the ootype.
• The vitellaria and their ducts penetrate the ootype into the yolk cells and the cytoplasm with nutrient material. Such an environment is necessary for the normal development of each fertilized egg.
• Each egg is surrounded by a nutrient shell, around which a dense shell is formed. The outer shell consists of granules of the yolk cells.
• The already formed egg enters the uterus and gradually moves to the exit. The fertilized egg (marita) exits the intestine of the carrier and must be introduced into the water for further development. In the aquatic environment, it turns into miracidia.

It is in this form that the helminth enters the human body or large cattle. In order to get infected, it is enough to drink unpeeled water or eat vegetables / fruits, washed in parasite-contaminated liquid.

[16], [17], [18]

Miracidia of the liver trematode

Larvae or miracidia of the liver fluke develop from marites, that is, fertilized eggs of a flat worm that have fallen into the water. The larva appears after 2-3 weeks of being in the aquatic environment. Their dimensions are very small - 0.02-0.34 millimeters. Life without water is 12-24 hours.

• Miracidia is an actively floating form, the body of which is covered with cilia. This skin provides rapid movement.
• The behavioral adaptive responses of the larvae of the first stage cause it to rise upward towards the light. Due to this, the future parasites gather on the surface film of water, where the ponders grow. Mycicides have a well developed chemical sensation, so they actively react to the mucus secreted by mollusks.
• The larva itself does not feed, but survives and develops due to the nutrients accumulated in the egg. It parasitizes in freshwater pond snails. Such a carrier is the gastropod (snail). Its main task is to find the next owner for further development.

Once the pond snake is found, the larva penetrates into its body with the help of special devices. At the anterior end of her body is a large gland, the ducts of which open on a muscular proboscis. The parasite is attached to the body of the mollusk by the proboscis and secrete the secret of the gland dissolving the tissue of the carrier. This process is carried out with the help of rhythmic muscle contractions and takes about 30 minutes. After this miracidium dumps the cilia, turning into a sporocyst.

Cercariae of the liver fluke

The larvae emerging from the body of the first host to search for the next one is the cercaria of the hepatic trematode. His body resembles an adult worm. Helminth has suckers, digestive, excretory systems and the brain are already formed, but do not act. The worm has eyes, it perceives chemical and mechanical irritation.

The main difference of this stage of fluke from an adult is the presence of a long tail with developed musculature at the posterior end of the body. Such a structure ensures free swimming and mobility of the larva. Leaving the body of the mollusk, the cercariae again enters the water. After a while, it crawls out onto the grass, throws off its tail and becomes covered with a cyst (a thick shell), inside which it maintains its viability.

[19], [20]

Cysts of the liver fluke

Sporocyst is a form of development of a flat worm in which reproduction occurs. Cysts of the liver fluke or redia are in a large embryonic sac. Gradually they depart from the maternal sporocyst, which leads to a large increase in the number of embryos. The larvae gradually migrate to the liver of the mollusk.

• The cyst has a well-developed skin-muscular sac.
• The nervous system, like sensory organs, is poorly developed.
• At the posterior end of the body there are two motor outgrowths, and in the anterior part - the genital pore.
• The digestive system is a muscular pharynx and a sacciform sac. Redia feed on the tissues of the liver of a mollusc, absorbing nutrients throughout the surface of its body.

Cysts multiply in parteconomically (without fertilization). Germ cells in the worm's cavity give rise to the next generations and cercariae.

[21]

Adolescaria of the liver trematode

A fixed cyst, attached to plants or objects in a pond, is the adolescaria of the hepatic trematode. It is formed in the external environment from the cercariae, that is, the intermediate host. The process of transformation of free cercaria into adolescaria is a cystonia.

• The outer shell of the larva has an uneven, layered surface.
• The lower shell is fibrous and thin. It separates the outer shell from the cyst.
• The inner membrane lining the fluid-filled worm cavity.

Together with water or plant food Adolescaria gets to the final host, turning into a sexually mature parasitic individual - marita.

[22]

Adaptations to parasitism in the hepatic trematode

The causative agent of fasciola has adaptations to parasitism. In the hepatic trematode, they are associated with its body shape, dense protective shell, the presence of suckers and hermaphroditism.

Common adaptations to fluke parasitism:

• Cuticle (skin) protects against digestion of the host's juices.
• Many mounts to the carrier: suckers, spikes, hooks.
• Regressive development of the sense organs and the nervous system.
• Simple structure of the digestive system.
• High fertility.
• A complex cycle of development with alternation of ways of reproduction and change of hosts.

Huge fertility is associated with a parasitic way of life, since the chance to get into the body of the final host is minimal. To survive, the parasite lays many eggs with asexual reproduction (embryos repeatedly divide).

[23], [24], [25],

Life cycle of the hepatic trematode

Fasciola is characterized by frequent transformations and a change of hosts. The life cycle of the hepatic trematode is represented by the following chain:

• The ultimate host.
• Egg.
• The miracidia.
• Intermediate host (pond snail).
• Sporocyst.
• Maternal redia.
• Subsidia redias (cysts).
• Cercaria.
• Adolescaria.
• Adolescaria in the external environment.

The hepatic fluke begins to develop from the egg from which the miracidium comes out. The larva has a nerve ganglion, excretory organs and a photosensitive eye. At the rear of the embryonic cells are located. The front of the body has a gland that produces an enzyme that dissolves living tissue and penetrates into the intermediate carrier. The parasite is covered with cilia and actively moves in the aquatic environment. It feeds on substances stored in the egg.

At the next stage of its life cycle, the hepatic trematode passes into the sporocyst. This larva is like a shapeless bag without organs, excretory and nervous system. At this stage, reproduction takes place without fertilization with the help of germ cells. The sporocyst bursts and redias emerge from it, which parasitize in the same carrier.

Redia has a number of formed organs: the mouth, the digestive tube and pharynx, the hole for the exit of eggs. Each cyst contains germ cells, from which the following larval generation - cercariae is formed. Cercariae has suckers, intestines, excretory and nervous systems. The larva has a long muscular tail. The cercaria leaves the mollusc and moves in the water.

Free-floating cercariae are attached to the stems of plants and objects in water, covered with a shell. This stage is called Adolescaria. The future fluke has a spherical shape. If the larva swallows the animal from the number of the final hosts, then the fasciola shell dissolves in the intestines of the carrier and the helminth enters the liver, where it develops to the sexually mature state. Invasion of animals occurs when eating grass on floodplain meadows and when drinking water from infected water bodies. Infection of people is carried out through contaminated vegetables.

Ways of infection with the hepatic fluke

The causative agent fascioliasis is indiscriminate in the choice of hosts: it can develop both in the animal and human body. Ways of infection with the hepatic fluke are associated with its life cycle. The parasite is a hermaphrodite, that is, at any stage of development, the larva can produce itself similar and in large quantity. Helminth develops in the external environment, since its larvae get there after birth. As a rule, these are ponds or wetlands. Worms are attached to plants, getting into the body of a new victim.

Allocate risk groups that have an increased chance of catching fascioliasis:

• People, whose traditional cuisine includes dishes from raw meat and fish.
• Hunters, fishermen and people working with land or in nature.
• Children playing with land or sand, resting in camps located in nature.
• Vendors in meat and fish stores.

The ways of infection of people and animals are similar. In the animal body, the liver fluke enters with contaminated grass or water. A person becomes infected in the same way by eating dirty vegetables, fruits, herbs. Another source of infection is water with worm larvae. There are also cases when fasciola was introduced into the human liver with insufficiently fried fish.

Eggs fluke for humans do not carry danger. They can enter the body with water or food, but their further development in the human intestine is impossible. Larvae are excreted from the body with feces. But this is not the end of their life cycle. The future helminth enters the sewer water and develops to the next stage, getting into the reservoirs, where they are eaten by animals. Therefore it is very important to use only purified water, thoroughly wash the products before use and conduct their thermal treatment.

[26]

Intermediate host of hepatic trematode

Molluscum pond is the intermediate host of the liver fluke. The larva of the parasite is introduced into the body of the cochlea, where it lives and develops at its expense. The grown-up individual leaves his carrier, and is attached with suction cups and thorns to the stems of water and coastal plants. At this stage, the helminth is covered with a protective shell - shell.

This stage is called aledoskarii. The worm can exist in an aquatic or humid environment for a long period of time, preserving its viability. As soon as the larvae enter the body of the final host, and this may be an animal or a person, then they continue their development to the mature individuals. An acceptable environment for the survival of parasite progeny are animals and human excrement. With them, the eggs of the worm get into the reservoirs, repeating their life cycle.

The main host of the hepatic trematode

Herbivorous mammals (large and small cattle, pigs, horses, rabbits) and man - this is the main owner of the hepatic trematode. Infection occurs when you use infected plants or water with eggs or larvae of the parasite.

Most often helminths settle in the gallbladder or liver, but any other organs can be affected: kidneys, stomach, pancreas, bile ducts, spleen. Getting into the digestive system of the main host, the fluke loses its hard shell and moves to the bloodstream through the walls of the intestine. With the blood flow, the parasite "walks" around the body, settling in the liver or nearby organs. At this stage, a transformation occurs in a matured individual.

With the help of suckers, thorns and hooks, the worm is attached to the living tissues of the carrier, lives and develops at their expense. After a while, the helminth begins to multiply actively. His eggs with a current of bile penetrate into the intestines of the host, and from there with feces out.

Symptoms

Symptoms of fascioliasis are manifested in different ways. Symptoms of the hepatic trematode at an early stage of infection are characterized by such pathological conditions:

• Unreasonable muscle pain.
• Disturbances of the gastrointestinal tract.
• Dermatological reactions: itching, rash.
• A sharp increase in temperature, fever.
• Increased weakness and fatigue.
• Painful sensations in the liver.
• Sharp weight loss.
• Impairment of immunity.

In most cases, the above symptoms are not taken seriously. They are written off for the wrong food, non-observance of the rest and work regime, bad ecology and much more. As the symptoms are ignored, they become more pronounced and progress. Infected begin to complain about:

• Problems with sleep.
• Disorders of the stomach and biliary colic.
• Increased irritability and frequent mood changes.
• Frequent headaches, dizziness, migraine.
• Painful sensations in the right hypochondrium, giving in the back.

In some cases, infection with the causative agent of fascioliasis is asymptomatic. Helminths may not be felt for 3-5 months. Because of this, the pathological condition is detected at the advanced stage, which significantly complicates the treatment.

[27], [28], [29],

Diagnostics

Based on the presence of eggs of fluke in the feces, diagnostics of the hepatic fluke is carried out. The parasite can be found in healthy people, after drinking contaminated water or food. Eggs begin to excrete with excrement 3-4 months after infection. In the acute phase of fascioliasis, the diagnosis is made on the basis of painful symptoms.

In the diagnostic process, the following methods are used:

• Collection of anamnesis, that is, epidemiological data: bathing or drinking water from inadequate reservoirs, using unwashed vegetables, fruits, and also fish, meat or liver of animals.
• Clinical signs of pathology: early symptoms and signs of chronic form of fascioliasis.
• Laboratory tests depend on the stage of the disease. In the early phase, serological methods are used, that is, the study of blood for antibody-response ELISA, RNGA. With advanced stages, a coproovascular or duodenoscopy is performed.

Based on the results of the diagnostic procedures performed, the doctor makes the final diagnosis and prescribes a helminth treatment regimen.

[30],

Analysis for hepatic trematode

Laboratory diagnosis of fascioliasis is carried out 1,5-3 months after the alleged infection. Analysis for baker's flukes is a highly effective immunological examination for the detection of specific antibodies in the blood serum.

In many patients, there are increased values of eosinophils and leukocytes in a general blood test. Chronic stages are characterized by normal values of leukocytes and insignificant eosinophilia. If the background of fascioliasis is the attachment of a bacterial infection, then the erythrocyte sedimentation reaction increases.

Mandatory examination of micropreparation of feces or contents of the duodenum is mandatory. When infected, yellowish-brown eggs are found, with a size of 135x80 μm. In case of doubtful results, a second examination of the bile with microscopy is carried out after 7-10 days.

[31], [32], [33], [34], [35],

Report on the liver flukes

Planned laboratory studies can reveal the presence of eggs of fasciolae. The report about the hepatic trematode, obtained as a result of the tests, requires additional and more thorough diagnosis and, of course, treatment.

Particular attention is paid to the method of infection. If the reason for the invasion is the consumption of purchased meat or liver, then a sanitary and veterinary investigation is carried out. This is necessary to establish the source of infection, its destruction and preventive maintenance of the parasite.

If fascioliasis appeared as a result of drinking polluted water or bathing in an impure water body, then it is necessary to apply to the sanitary and epidemiological service. This will significantly reduce the risks of morbidity and prevent a possible epidemic, both among humans and animals.

Differential diagnosis

If there is a suspicion of infection with the hepatic fluke, differential diagnosis is carried out with such diseases:

• Allergic reactions.
• Hepatitis.
• Cholangitis.
• Cirrhosis of the liver.
• Gastroduodenitis.
• Cholecystitis.
• Leukemia.
• Helminthiases (opisthorchiasis, clonorchiasis, trichinosis).

When eating the liver of an animal infected with a fluke, feces reveal transit eggs that have passed through the human gastrointestinal tract. Their detection does not carry diagnostic value. Therefore, during the differentiation, a twofold study of feces and duodenal contents (with an interval of 10-14 days) is carried out under a microscope for comparison with other helminthic lesions. Mandatory ultrasound and imaging of the abdominal organs.

[36]

Differences between bovine tapeworm and hepatic trematode

Floss and tapeworm belong to the category of flatworms. Differences between the bovine tapeworm and the liver flukes are that the first is a ribbon worm, and the second is from the flukes class.

Let's consider the main characteristics of these types of flat parasitic worms:

View	Hepatic fluke	Bull Chain
The main (final) host	Cattle, people	Human
Intermediate host	Mollusc pond snail	Cattle
Class	Flukes	Tape
The size	3-5 centimeters	1-3 m
Signs of parasitism	Suckers, high fecundity, simplified structure of organ systems.	Suckers (located on the head), high fecundity, no intestines.
Inhabitation and food	The liver of a person or animal, feeds on the tissues of the affected organ and blood.	The human small intestine, feeds on the contents of the intestine, sucking food throughout the body.
Eggs	They come out with the feces of the final host, get into the water and turn into a larva. It is introduced into the intermediate carrier, from which comes the next generation of the parasite - cyst.	They go out with feces from the final host, eaten up by pigs or cows. In the stomach of animals, larvae emerge from eggs, they have hooks, which helps to penetrate into the blood vessels and spread throughout the body. Getting into the digestive organs, the egg goes to the stage of the Finn.
Infection	Unboiled water, swimming in non-water reservoirs, eating dirty vegetables, fruits, greens, meat or fish.	Eating poorly cooked or raw meat.

 

The above described differences in parasites allow you to select the most informative methods for their detection, treatment and prevention.

[37], [38], [39]

Differences of the white planaria from the hepatic trematode

The main differences between the white planaria and the liver trematode are that the former acts as a parasitic predator and is looking for victims. While the causative agent of fascioliasis waits for the potential carrier to swallow it.

Consider the main differences between parasites:

View	Hepatic fluke	White Planaria
Class	Flukes	Ciliated worms
Dimensions and features of the structure of the body	The leaf form of the body is from 3 to 5 cm. At the anterior end of the body and the peritoneum, the oral and abdominal suckers are located. With their help, the worm is attached and held in the host's body. Moves at the expense of developed skin muscular sac. The ciliated epithelium is absent.	Body length about 1 cm, at the head end there are tentacles, which act as organs of smell and touch. There are two eyes. The body is covered with ciliated epithelium. Movement is carried out by a developed skin-muscular sac.
Inhabitation and method of nutrition	The habitat depends on the stage of development. Adult worms live in the ducts of the liver of herbivores and humans. Intermediate studio - mollusk prudovik, and eggs - are attached to plants in freshwater reservoirs. It feeds on blood and liver tissues.	The worm lives in fresh water. It feeds on slow-moving animals, covers them with its body and captures it with a pharynx.
Reproduction	Hermaphrodite. Already fertilized eggs are removed from the worm into the intestine of the carrier, and from there with feces into the external environment. Further development occurs in water.	Hermaphrodite. Eggs are deposited in dense cocoons, which are attached to underwater objects. From the eggs are already mature. Has high regenerative properties

 

White planaria is not a threat to humans, while fluke is the causative agent of fascioliasis.

[40], [41]

Treatment

Fasciolus has several stages of development, each of which is characterized by a certain symptomatology. Treatment of the liver trematode depends on the stage of the pathological process and the individual characteristics of the patient's body. Therapy should be comprehensive, it is carried out with the help of special medications.

1. Anthelmintic means for removing the worm from the body:

• Chloksil

Anthelminthic drug, used in helminthiases in the liver. Especially with fascioliasis, clonorchosis, opisthorchiasis. Powder is taken by a doctor-appointed scheme within two days. The first dose is taken an hour after breakfast - 0.1-0.15 g / kg body weight, daily dose of 6-10 g. If a five-day application of the drug is prescribed, the powder is consumed at 0.06 g / kg. The daily dose is calculated for 2-3 doses at an interval of 2 hours. The drug is recommended to be washed down with milk. If necessary, the course of treatment is repeated after 4-6 months.

The main contraindications are myocardial damage, liver disease, pregnancy. Possible side effects: pain in the liver, allergic reactions of varying severity, drowsiness, a general decline in strength.

• Praziquantel

Drug for the treatment of diseases caused by trematodes and flatworms. The mechanism of its action is based on increasing the permeability of parasite membranes for calcium ions. This leads to spastic paralysis of the helminth. As a rule, patients undergo 1-2 days of treatment with a dosage of 0.03 g / kg 2 times a day.

Side effects are manifested in the form of nausea, headaches and dizziness. There may be pain in the abdomen, skin allergic reactions, a sharp increase in temperature. Overdose manifests more intense symptoms and is most often observed in patients with massive helminthic invasion.

Contraindications to the use of the drug are based on its mechanism of action. The drug is not prescribed in the early stages of pregnancy and lactation, with increased sensitivity to the components of the remedy. With special care is used for patients with ocular cysticercosis.

• Triclabendazole

Anthelmintic means of a narrow spectrum of action. It is used for fascioliasis, paragonism and other parasitic lesions. The drug has a tablet form of release, each capsule contains 250 mg of active substance. Its mechanism of action is associated with the inhibition of the muscular system of worms, affects both adult individuals and larval forms. When infecting the hepatic fluke, 10 mg / kg of body weight are taken in one dose, with severe forms of invasion, twice with an interval of 12-24 hours. Repeated treatment is possible after 2-6 months.

Contraindications: patients with renal and hepatic insufficiency, pregnancy and breastfeeding, hypersensitivity to the drug components. The medicine is not prescribed for children under 6 years of age. Adverse reactions occur rarely, and can manifest in the form of nausea, dizziness, allergic reactions and indigestion, headaches.

2. Cholagogue preparations for accelerating the excretion of helminth and restoring the functioning of damaged organs:

• Hofitol

Medicinal product based on dry aqueous extract of artichoke field. Active components of the plant have choleretic, diuretic and hepatoprotective effects. Decrease the level of urea in the blood, improve the cholesterol metabolism and metabolism of ketone bodies. Artichoke contains vitamins of group B, which normalize metabolic processes in the body and purify it of toxins, alkaloids and other harmful substances. If the medicine is used in complex antibiotic therapy, then it has a detoxification effect.

Indications for use: hepatitis, fatty hepatosis, atherosclerosis, acetonemia, cholecystitis, cirrhosis and other liver damage. The drug has several forms of release: tablets, injections and solution for oral administration. The dosage depends on the type of medication and the flow of the fascioliasis, therefore it is prescribed by the doctor, individually for each patient.

Adverse reactions are possible when taking the drug for a long period of time or using high doses. In this case, patients face various allergic reactions and a gastrointestinal disorder. The main contraindication is the obstruction of the biliary tract, acute liver and bile duct disease, renal failure, hypersensitivity to the components of the agent. In case of an overdose, there is an increase in side-effects.

• Allochol

A drug that increases the formation of bile. The mechanism of its action is based on reflexes of the intestinal mucosa and secretory function of the liver. The drug increases the amount of secreted bile, strengthens the motor and secretory functions of the digestive tract, reduces the processes of putrefaction and fermentation in the intestine.

Tablets are prescribed for chronic hepatitis, cholecystitis, cholangitis, constipation caused by intestinal atony. The drug is taken 2 tablets 3 times a day after meals. The course of treatment is 1 month. Side effects occur extremely rarely, and are manifested in the form of allergic reactions and diarrhea. Allochol is not prescribed in acute stages of hepatitis, liver dystrophy and obstructive jaundice. In case of an overdose, there is an increase in adverse reactions and an increase in the level of transaminases in the blood.

3. Additional use of enzymes:

• Pancreatin

The drug contains the enzymes of the pancreas, which are necessary for the normal functioning of the body. Pancreatin is used when the secretory function of pancreatic, inflammatory-dystrophic diseases of the stomach, liver, intestine or gallbladder is insufficient. Helps with violations of digestion of food, diarrhea and increased flatulence. Dosage and duration of treatment depend on medical indications. As a rule, the medicine is taken 1-2 capsules 2-3 times a day for a month.

Contraindications: hypersensitivity to the components of the drug, acute pancreatitis or exacerbation. Adverse reactions are manifested in the form of skin allergic rashes and digestive tract disorders.

• Mezim

Enzyme agent with pancreatoprotective activity. It is used for hypoxecretion of pancreatic enzymes and functional abnormalities of the gastrointestinal tract, for pathologies and dysfunction of the digestive organs and for improving the digestion of food. Tablets are taken with meals, 1-2 pcs. 2-3 times a day. The course of therapy varies from a single to three-day use.

Side effects are manifested in the form of allergic reactions, painful sensations in the epigastric region and attacks of nausea. In case of an overdose, there is an increase in the concentration of uric acid in urine and blood. Mezim is contraindicated in acute pancreatitis or its exacerbations, with individual intolerance of the components of the agent.

• Creon

Medicinal preparation in the form of gelatin capsules with porcine pancreatin. Has a lipolytic and amylolytic effect, improves the absorption of food in the intestine. It is used for enzymatic insufficiency caused by such diseases: pancreatitis, a condition after gastrectomy or pancreatectomy, with cystic fibrosis, neoplasms in the pancreas and other diseases with pancreatic enzyme deficiency.

The dosage depends on the indications and general condition of the patient's body, therefore it is prescribed by the doctor. Side effects are manifested in the form of allergic reactions and disorders of the gastrointestinal tract. Contraindications: intolerance to pancreatin of porcine origin, acute pancreatitis, pancreatic hyperfunction. In case of an overdose, hyperuricemia and hyperuricosuria may develop.

If the hepatic fluke has become the cause of purulent complications, then patients are prescribed antibacterial drugs. In the case of liver abscess, drainage is shown, that is, surgical treatment of fascioliasis. In the acute phase of the disease, a diet is shown in which all foods that exert an additional load on the liver are excluded from the diet. If fascioliasis accompanies the symptoms of hepatitis or myocarditis, the patient is assigned glucocorticosteroids.

To control the quality of the therapy, six months later, a laboratory study of feces for helminthiasis, study of bile and blood test for antibodies was shown. If the treatment was successful, then the IgG antibody titer is lowered, if the titer is raised, then repeated therapy is necessary.

Prevention of the hepatic trematode

To minimize the risk of infection with hepatic fluke it is necessary to follow preventive recommendations. Prevention of fascioliasis consists of such rules:

• Observance of cleanliness in everything. Washing hands after toilet and before each meal. It is necessary to thoroughly wash salad grasses, vegetables and fruits, if possible, pour them with boiling water or blanch before consumption.
• Particular attention should be paid to heat treatment of products. Fish caught from the pond cook or stew, even if it is intended for pets (cats carrying fascioliasis). Do not consume raw meat or liver.
• Exclude the use of unboiled or unrefined water from non-water reservoirs. It is not recommended to swim in stagnant water.
• Regularly carry out anthelmintic treatment of domestic animals. Observe the sanitary and veterinary standards. It is also recommended to clean ponds and fight against mollusks (intermediate helminth master) in water bodies.

The hepatic trematode is not the most terrible representative of flatworms, but since the ways of its infection are known, it is better to follow the rules of prevention. At the first symptoms or suspicion of invasion, it is necessary to consult an infectious disease specialist and a gastroenterologist.

[42], [43]

Forecast

With timely diagnosis and proper therapy, the prognosis of fascioliasis is favorable. But if the infection is detected in the late stages, it can lead to irreversible consequences.

The main complications of parasite infection are:

• Abscess of the liver.
• Cirrhosis of the liver.
• Subcutaneous abscesses.
• Purulent angiocholangitis.
• Chronic cholecystitis.
• Mechanical jaundice.

Helminth can severely injure the mucous membrane, causing blockage of the bile ducts. It can also lead to lung and breast damage. The prognosis for the above-described complications, massive invasion or attachment of a secondary bacterial infection is not very favorable.

The hepatic fluke requires complex therapy. It is very dangerous to engage in self-medication. Since only a doctor can prescribe effective drugs for the destruction of the parasite and methods of rehabilitation to restore the organs, after the invasion. Particularly severe and neglected cases can lead to death.

[44], [45], [46]