Type Roundworms. Structure, internal systems, comparison with other types of worms

General characteristics of the type Roundworms. Roundworms, or nematodes, live in the seas, fresh water and soil. Among them are many species that affect the tissues and organs of not only various animals and humans, but also plants. It has been established that there are no such biotopes on our planet, where there would be no representatives of the type of roundworms. This is one of the numerous types of the animal world, including more than 500 thousand species. The length of representatives of various species ranges from 1 mm to 1 m, and sometimes more.

The body of roundworms is not segmented and has bilateral symmetry. On the cross section it has the shape of a circle, which is why they got such a name. The body wall consists of a skin-muscular sac, covered on the outside with a cuticle. The internal organs are located in the primary cavity of the body, filled with fluid, which washes the skin-muscle sac from the inside. The excretory system in roundworms is represented by one or two unicellular skin glands, from which two lateral canals depart. Behind, they end blindly, and in the front they are connected into one channel, sometimes opening outward behind the "lips". The function of excretion is also performed by special phagocytic cells located along the excretory canals. They accumulate insoluble dissimilation products and foreign bodies that enter the body cavity.

The central nervous system is represented by a nerve parapharyngeal ring with trunks extending from it. The sense organs are poorly developed. There are organs of touch and chemical sense. Free-living nematodes have photosensitive eyes.

The digestive system starts at the mouth and ends at the anus.

Most forms of roundworms are dioecious with well-defined sexual dimorphism.

The most common representatives of the class Proper roundworms (Nematoda) are human roundworm, pinworm, whipworm and trichinella. (Ascaris lumbriсoides, Enterobius vermicularis, Trichocephalus trihiurus, Trichinella spiralis).

Ascaris human(Ascaris lumbricoides). Causes ascariasis.

It occurs everywhere, except for the Arctic and arid regions (deserts and semi-deserts).

Localization. Small intestine.

Pathogenic action. 1. Larval forms during migration can cause bronchopneumonia. The severity of symptoms is related to the intensity of invasions. 2. Mature forms can cause intoxication of the body and its consequences - malabsorption of fats, proteins, carbohydrates and vitamins, and can also cause mechanical blockage of the intestinal lumen and bile ducts.

Diagnostics. Detection of eggs in faeces.

Control measures and prevention. Patients need to be identified and treated. Of particular importance is the introduction into everyday life of washing and heat treatment of berries, vegetables, herbs and fruits consumed raw. It is necessary to rinse the vegetable products well with clean cold water before heat treatment, then dip in a colander for 2-3 seconds in boiling water or for 8-10 seconds in hot water (70-76 0 C) and then immediately rinse the products with cold water. Heat treatment of plant products should be carried out immediately before eating them. Hands should be washed with soap after working in the garden, berry and orchard, and for children after playing on the ground.

Taking into account the long-term survival of roundworm eggs in the soil and their intense pollution of the external environment, the following measures should be taken: prohibition of fertilizing gardens and berries with untreated feces, keeping toilets in proper sanitary and hygienic condition, reliable disposal of sewage and sewage, improving sanitary and hygienic skills of the population.

Human pinworm (Enterobius vermicularis)- the causative agent of enterobiasis. Geohelminth.

Geographic distribution. Everywhere.

Localization. The lower part of the small intestine and the initial part of the large intestine.

The worm is pinkish white. The length of the female is 10-12 mm, the male is 2-5 mm. Sexual dimorphism is pronounced. The mouth opening is surrounded by lips (Fig. 33). At the anterior end of the body of the helminth, a swelling of the cuticle is found - a vesicle that surrounds the mouth opening. The vesicle is involved in the fixation of the helminth to the walls of the intestine. This function is also performed by the bulbus - a spherical swelling of the back of the esophagus.

development cycle. Geohelminth. The male dies after fertilization. The fertilized female descends into the rectum under the influence of peristalsis (Fig. 33). At night, she actively crawls out of the anus and releases eggs on the perianal folds. Shortly after laying, the female dies. The eggs contain an almost formed larva, and their full maturation occurs in the external environment after 4-6 hours with the access of oxygen. The life span of pinworms is 3-4 weeks. Pinworm eggs develop on the human body, which creates conditions for autoreinvasion.

pathogenic action. Itching and skin lesions in the anus, as a result of which the patient's sleep is disturbed. With intense enterobiasis, pinworms crawl into the vagina and cause inflammation in the genitals of girls and women. This may be accompanied by headaches, dizziness, abdominal pain, nausea and loss of appetite.

Diagnostics. Scraping from the perianal skin folds, obtaining a smear and microscopic examination of it for the detection of eggs and larvae. The eggs and larvae of the pinworm can be found under the nails of the patient, the larvae - on the skin of the perineum. Sexually mature individuals are sometimes excreted with faeces.

Prevention: a) public - sanitary and educational work, systematic, preventive measures in children's groups; b) personal - compliance with the rules of personal hygiene, washing hands, caring for nails. The patient should sleep in underwear. In the morning it is necessary to boil and iron the linen.

Whipworm human (Trichocephalus trihiurus) - the causative agent of trichuriasis.

Geographic distribution. Everywhere.

Localization. In the caecum, appendix, the initial section of the large intestine.

Morphological characteristic. The female is 3.5-5.5 cm long, the male is 3-5 cm. Males have a spicule at the tail end. Whipworm eggs are shaped like barrels, with lids on both sides.

development cycle. Geohelminth. The fertilized female lays eggs in the intestinal lumen, from where they are thrown out with feces. The egg develops in the external environment under optimal conditions (temperature 26-30 0 C, high humidity and oxygen) for four weeks and becomes invasive. The development of the whipworm, unlike roundworm, proceeds without migration. Infection occurs when eating vegetables, berries and unboiled water contaminated with eggs.

Pathogenic action consists in intoxication, causing nervous disorders, anemia, pain in the abdomen. Vlasoglavy can cause an inflammatory process in the appendix. With a high degree of invasion (more than 800 helminths), anemia develops.

Diagnostics. Based on the presence of eggs in the feces.

Prevention. The same as with ascariasis.

Trichinella (Trichinella spiralis) - the causative agent of trichinosis anthropozoonosis, a natural focal disease (Fig. 35).

Geographic distribution. On all continents of the world. It has a patchy distribution.

Localization. Adults live in the small intestine, larvae - in certain muscle groups: diaphragm, intercostal, chewing, deltoid, gastrocnemius.

Morphological characteristic. Small thin nematodes. Female 3 - 4 mm, male 1.4 - 1.6 mm. The head end of the helminth is slightly pointed, the esophagus is located here. In males, the caudal end has two pairs of papillae; the spicule is absent. In females, the reproductive system is represented by an unpaired tube. Live birth is typical.

pathogenic action. A symptom complex typical for this disease is swelling of the face, eyelids, a sharp rise in temperature, muscle pain. The severity of the disease depends on the number of larvae settled in the tissues of the host organism. Five larvae per 1 kg of body weight is a lethal dose.

Diagnostics. Clinical picture at the first stage of the disease, patient questioning, muscle biopsy (deltoid or gastrocnemius) to detect encapsulated larvae, skin-allergic test. For early diagnosis, immunological reactions are carried out.

Prevention: a) public - sanitary and educational work, sanitary and veterinary control of animal fat and meat, b) personal - do not use meat products that have not passed veterinary control.

Type Flatworms General characteristics of the type

The characteristic features of the type are as follows :

1. The body is flat, its shape foliate(in cilia and flukes) or ribbon-like(in tapeworms).

2. For the first time in the animal kingdom, representatives of this type developed bilateral(bilateral ) body symmetry, i.e., only one longitudinal plane of symmetry can be drawn through the body, dividing it into two mirror-like parts.

3. In addition to the ectoderm and endoderm, they also have an average germ layer - the mesoderm. Therefore, they are considered the first three-layered animals. The presence of three germ layers provides the basis for the development of various organ systems.

4. Body wall - the totality of the outer single-layer epithelium and those located under it several layers of muscles- circular, longitudinal, oblique and dorsal-abdominal. Therefore, the body of flatworms is capable of performing complex and varied movements.

5. No body cavity, since the space between the wall of the body and the internal organs is filled with a loose mass of cells - parenchyma. It performs a supporting function and serves as a depot of reserve nutrients.

6. Digestive system consists of two sections: ectodermal anterior guts, represented by a mouth and a muscular pharynx, capable of turning outward in predatory ciliary worms, penetrating the victim and sucking out its contents, and a blindly closed endodermal midgut. In many species, many blind branches extend from the main sections of the midgut, penetrating into all parts of the body and delivering dissolved nutrients to them. Undigested remains of food are thrown out through the mouth.

7. Excretory system of protonephridial type. Excess water and metabolic end products (mainly urea) are excreted through excretory pores.

8. Nervous system more concentrated and represented by a paired head node (ganglion) and longitudinal nerve trunks extending from it, connected by annular bridges. The nerve trunks are formed by the bodies of nerve cells and their processes located along its entire length. This type of organization of the nervous system is called stem. All flatworms have developed organs of touch, chemical sense, balance, and free-living ones have vision.

9. Flatworms - hermaphrodites(with rare exceptions). Fertilization is internal, cross. In addition to the sex glands (ovaries and testes), a complex system of genital ducts and additional glands have been developed that provide the zygote with nutrients and material for the formation of protective egg membranes. In freshwater ciliary worms, development is direct, in marine ones, with a planktonic larval stage.

Class Tapeworms

1. They have completely lost their own digestive system and absorb the food digested by the host with the entire surface of the long ribbon-like body.

2. The reproductive system is repeated in each segment.

Bull tapeworm- one of the largest (about 10 m long) representatives of the class (Fig. 11.5). The adult worm lives in the human small intestine (main host), its larva lives in the muscle tissue of cattle (intermediate host).

The body consists of a head, neck and segments (about a thousand). The head carries four powerful suction cups. It is followed by the neck - the zone of budding of young segments. Old segments move back and have the ability to grow, so their size increases in the direction from the head to the posterior end of the body.

Rice. 11.5. Bull tapeworm: 1 - appearance; 2 - head (suckers are visible); 3 - segments.

Fertilization is internal, cross, rarely self-fertilization. The last 3-5 segments periodically separate from the body of the worm and are excreted from the human body along with feces. These segments are called "mature", as they are completely filled with fertilized eggs, the number of which in one segment reaches 200 thousand. For a year, a bull tapeworm forms up to 600 million eggs. Its life expectancy is about 20 years.

From the external environment, the eggs, along with the grass, enter the intestines of cattle. In the intestine, a microscopic larva with six hooks emerges from the egg. With their help, it perforates the intestinal wall and enters the lymphatic and blood vessels, through which it spreads to a variety of internal organs. Some of the larvae get stuck in the muscle tissues, grow and turn into a bubble stage - Finn - a small bubble filled with liquid, with a head with four suckers screwed into it. When eating poorly cooked or fried meat infected with Finns, in the human intestine, the heads of the worm turn out and attach to the intestinal wall. The neck of the worm begins to separate segments, the bubble soon disappears.

The class Tapeworms also includes pork tapeworm, echinococcus, wide tapeworm, etc.

Unlike bullish pork tapeworm , in addition to suckers, has hooks on the head, with the help of which it is even more firmly attached to the wall of the human intestine. Its intermediate host is the pig.

Most dangerous to humans tapeworm echinococcus . His finna forms a bubble the size of a baby's head. An adult tapeworm is only 5 mm long. Lives in the small intestine of a dog, fox, wolf. The Finn stage takes place in various organs (especially in the liver and lungs) of cattle, sheep, pigs, and also humans. Humans become infected through careless handling of dogs. Treatment of echinococcosis is possible only by surgery.

Class Ciliary worms

This class includes free-living marine and freshwater, rarely terrestrial worms, the entire body of which is covered with ciliated epithelium. The movement of the worms is provided by the work of the cilia and the contraction of the muscles. Many species are characterized by regeneration.

A typical representative of ciliary worms - milky white planaria - lives in fresh stagnant water bodies on underwater objects and plants (Fig. 11.4). Its flat body is elongated, at the front end of which two small tactile tentacle-like outgrowths and two eyes are visible.

Planaria is a predatory animal. Her mouth is located on the ventral side, almost in the middle of the body. With the help of a muscular pharynx protruding outward, the planaria penetrates into the prey and sucks out its contents. In the branching middle section of the intestine, food is digested and absorbed.

Excretory organs - protonephridia. They are represented by two branching canals, at one end opening outwards excretory openings, and at the other - by stellate cells scattered in the parenchyma. The stellate part of the cell passes into a canal, inside which a bundle of cilia is located. Liquid metabolic products seep into the pear-shaped extension of the initial section of the canal. Protonephridia are located on the sides of the body.

Rice. 11.4. Scheme of the structure of dairy planaria: a - digestive and nervous systems; b- excretory system: 1 - posterior branches of the intestine; 2 - lateral nerve trunk; 3 - head ganglion; 4 - anterior branch of the intestine; 5 - pharynx; 6 mouth opening; 7 - channels of the excretory system.

The nervous system consists of clusters of nerve cells - the head ganglion. Nerve trunks depart from it to the sense organs - the eyes and the organs of touch - lateral outgrowths. To the posterior end of the body from the head node are two longitudinal nerve trunks, interconnected by transverse bridges. Numerous nerves depart from the longitudinal nerve trunks.

Planaria is a hermaphrodite. Fertilization is internal, cross. The development is direct.

Flukes class

2. various organs of attachment to the host body: suckers, hooks, etc.;

3. regressive development of the nervous system and sensory organs;

4. simply arranged digestive system or its absence;

5. extremely high fertility;

6. complication of the development cycle, consisting in the alternation of methods of reproduction and the change of hosts. In the body of the main host, sexual reproduction of the worm occurs, in the body of the intermediate host, asexual reproduction occurs.

class representative- liver fluke settles in the bile ducts of cattle (rarely humans) and feeds on blood and nutrients accumulated in liver cells. The body is leaf-shaped, flattened, up to 5 cm long, covered with a dense cuticle. The organs of attachment to the body of the host are two suckers: the anterior - oral, and abdominal. The digestive and excretory systems are not fundamentally different from those of ciliary worms. Simplification of the nervous system is expressed in a decrease in the size of the head ganglion. The sense organs are poorly developed.

The development cycle of the fluke is complex, with the change of several generations and one sexual. After internal fertilization and maturation, the eggs must enter the water, where a floating larva emerges from them. Having found a snail - a small pond snail, she penetrates his body. In it, the larva of the worm undergoes a series of transformations and parthenogenetically reproduces twice. As a result, a generation of larvae is formed, resembling an adult fluke in structure, but having a muscular tail appendage. At this stage, the larvae leave the body of the pond snail (intermediate host), enter the water and settle on coastal vegetation. Here they lose their tail and become covered with a dense protective shell. With green food, cysts can enter the body of domestic animals (the main host), where they turn into adult liver flukes. A person can become infected with them when drinking raw water from a reservoir, as well as vegetables and fruits washed in this water.

Preventive measures: destruction of small pond snails in local water bodies and human compliance with hygiene rules.

Type Roundworms General characteristics of the type

The characteristic features of the type organization are as follows :

1. body thin, cylindrical, elongated and pointed at the ends. It is round in cross section.(which gave the name to the type).

2. Skin-muscular sac It consists of an external multi-layer cuticle that does not have a cellular structure, a single-layer epithelium located under it and a layer of longitudinal muscle fibers, due to contractions of which the body can bend serpentine.

3. Body cavity - primary, filled with a liquid under greater than atmospheric pressure. The cavity fluid gives the body elasticity and thus acts as a hydroskeleton. It also provides transport of nutrients and waste products.

4. For the first time in the animal kingdom the digestive system is represented by a through digestive tube, subdivided into three sections - the anterior, middle and hindgut. The anterior section begins with a mouth opening leading to the oral cavity and pharynx, which can work as a pump. The pharynx is separated from the midgut by a valve. In the midgut, food is digested and absorbed. The midgut is followed by the ectodermal hindgut, which opens on the ventral side of the body as an anus.

4. excretory system represented by a pair of lateral longitudinal canals, merging under the pharynx into one duct and opening on the ventral side of the body with an excretory opening. The end products of vital activity accumulate in the cavity fluid, and from it they enter the excretory canals.

5. Nervous system It is represented by an annular peripharyngeal ganglion and several longitudinal nerve trunks extending from it, interconnected by semicircular nerve bridges. There are organs of taste, touch, and free-living roundworms have light-sensitive eyes..

6. Roundworms - dioecious animals that reproduce only sexually. In roundworm, males and females are outwardly distinguishable (sexual dimorphism). The reproductive system has a tubular structure: in the female - paired ovaries, oviducts, uterus and unpaired vagina, in the male - unpaired testis, vas deferens, ejaculatory canal, copulatory apparatus. Fertilization is internal, development usually proceeds with incomplete transformation (with the larval stage).

Figure 11.6. Appearance (a) and internal structure (b) roundworm: 1 - mouth opening; 2 - throat; 3 - intestines; 4 - vagina; 5 - uterus; 6 - oviduct; 7-ovary; 8 - ejaculatory canal; 9 - testis; 10 - seed tube.

The development cycle is complex, associated with the release of eggs into the external environment and the migration of larvae in the human body. Fertilized eggs, covered with dense protective shells, from the human intestine enter the soil. In the presence of oxygen and a sufficiently high temperature, a larva develops in them for about a month. The egg becomes contagious (invasive). With contaminated water and food, eggs enter the human small intestine. Here the larvae are released from the shell, pierce the intestinal mucosa with their elastic body and penetrate into the blood vessels. With the blood flow through the portal and inferior vena cava, they enter the right atrium, right ventricle and lungs (through the pulmonary arteries). From the lung tissue penetrate into the bronchi, from them into the trachea, and then into the pharynx. During migration, the larvae develop in the presence of oxygen. From the pharynx, they enter the intestines, where they complete their development cycle. Life expectancy is about a year.

Roundworms have a ubiquitous distribution and a high number of individuals, which indicates the biological progress of this group of animals. Their ancestors are considered ancient ciliary worms.

TYPE ROUND WORMS.

GENERAL CHARACTERISTICS

Roundworms are characterized by the following features:

1) The body has an elongated shape, not segmented, round in cross section.

2) Develop from three germ layers - ecto-; ento- and meso-dermis.

3) They have bilateral or bilateral body symmetry.

4) The body of roundworms has a skin-muscular sac formed by the hypodermis above which there is a dense cuticle that performs a protective function - it protects the worm's body from damage and the action of the host's digestive enzymes and the function of the external skeleton and support for muscles. Musculature is represented only by longitudinal muscles, which only allow the body to bend.

5) In roundworms, for the first time, a body cavity appears, which does not have its own epithelium and is called primary. The body cavity contains all the organs and cavity fluid under pressure. They play an important role in metabolism.

6) Digestive system - open type. Mouth, pharynx, esophagus, intestines, which has three sections - anterior, middle and posterior, which ends with an anus.

8) The nervous system is represented by a near-pharyngeal nerve ring, from which three pairs of nerve trunks extend along the body, the most developed are the lateral ones, between which there are jumpers or commissures. The sense organs are poorly developed, there are tactile cells and chemical sense organs.

9) The excretory system is represented by unicellular skin glands with excretory ducts or protonephridia.

10) Reproductive system - roundworms have separate sexes. The genital organs of the tubular structure in males are filiform testes, vas deferens and ejaculatory canal, in females ovaries, oviducts, uterus and vagina, opening on the ventral side of the body. They have pronounced sexual dimorphism (female and male differ in appearance). Fertilization is internal. Most roundworms develop without a change of hosts and belong to the group - GEOGELMINTHS.

In roundworms, in the course of evolution, arose three large aromorphs.

1. Primary body cavity.

2. Open digestive system.

3. Separate cavity.

development cycle. Annually roundworm throws up to 200 thousand eggs into the soil, which are excreted from the human body along with feces. In the external environment, with the access of oxygen, after 24-25 days a larva develops in the egg, and such an egg becomes invasive. If the rules of personal hygiene are not observed, a person becomes infected with roundworm eggs. In the human intestine, the shells of the eggs dissolve, the released larvae penetrate the intestinal wall, penetrate into the bloodstream and, with the flow of venous blood, move through the liver, heart to the lungs. In the lungs, with the access of oxygen, it molts, grows and penetrates into the bronchi, trachea, oral cavity and, upon secondary ingestion, enters the intestines, where an adult roundworm grows from the larva. Larval migration lasts 2.5 months. There is no host change in the roundworm development cycle, the eggs develop in the soil, so they are in the GEOHELITH group.

Roundworm eggs are covered with three protective shells and remain viable for a long time.

Ascariasis is a dangerous disease manifested by intoxication of the body with ascaris metabolic products, pain in the intestines, and indigestion. Roundworms can cause intestinal obstruction, with a large accumulation, a perverted migration of roundworms can be observed - they crawl into other organs and damage them. Preventive measures - personal hygiene: do not eat poorly washed vegetables and fruits; destroy carriers of helminth eggs - flies, cockroaches; sanitation of toilets.

Other representatives of roundworms are: pinworm, rishta, whipworm, threadworm, trichina, trichinella, crookhead, intestinal pinworm and others.

Free-living nematodes:

• live in soil and water;
• participate in the ecology of all ecosystems;
• second in number only to arthropods.

The concentration of free-living nematodes is about 1 million individuals per 1 m3.

Harm to humans and animals:

Type roundworms are distributed throughout the globe.

General characteristics of the type

Circulatory and respiratory systems

In roundworms no respiratory and circulatory system. Almost all representatives of the nematode family live in anaerobic conditions, and receive oxygen and nutrients already in finished form.

In the hypodermal layer, glycogen accumulates, which is also split into butyric, valeric and other important organic acids. Absorption of ready-made nutrients occurs through the epithelial layer of the primary cavity (intestine), and accumulates in the hypodermis.

Such a primitive life support system makes the respiratory and circulatory systems superfluous in the existence of the worm.

Morphology

Body structure (from outer layer to inner):

• Pseudochain - the primary cavity, lined with epithelium (intestine).
• Coeloma - secondary cavity without epithelium.

Digestive system of roundworms

At the anterior end of the body there is a mouth opening with lips made of cuticular sweets. Further, the oral capsule begins (in some species armed with teeth), and then a small segment of the esophagus begins.

The entire digestive tract forms one rectum, which is divided into:

• front;
• average;
• back departments.

Some species do not have an anus.

Nervous system

Nervous system of nematodes:

• peripharyngeal ring- located in the middle of the pharynx with an inclination to the dorsal edge (in some species to the ventral)
• Ventral (abdominal) nerve trunk- goes along the lower plane of the body in the ventral ridge of the hypodermis. Other small nerve fibers originate from it.
• Dorsal (dorsal) nerve trunk- passes in the dorsal roller of the hypodermis. Does not "let" nerve fibers.

Also, roundworms can be guided by smell and light.

reproductive system

They belong to dioecious worms with pronounced sexual dimorphism. Females lay eggs, larvae can hatch either in the external environment or in the body of the female (live birth). The females are larger than the males.

The reproductive system of females is steam, tubular and consists of:

• ovaries;
• oviducts;
• uterus;
• vagina.

The ovaries are narrow, blindly curved, gradually turning into wider sections. The uterus is a steam room that extends into the vagina, which opens on the ventral side in front of the body. Females can be several times larger than males, the body is straight.

In males, the end of the body is spirally wrapped towards the abdominal plane.

The structure of the male reproductive system:

• Tubular seed.
• Semen tube.
• The vas deferens that opens into the posterior intestine.

On the cloaca there are copulatory spicules, with which the male holds the female.

In some species, the spicules have capulative burses, which are expanded and flattened in the form of wings, the lateral parts of the posterior end of the body.

excretory system

It consists of two tubules that begin in the back of the body, connecting to form a common duct that opens with an opening on the ventral side of the anterior end of the body. The movement of the body is carried out only in the dorsoventral (forward) direction.

Representatives of the nematode type in the human body

Ascaris human

The causative agent ascaris lumbricoides is a nematode, the length of the male is up to 25 centimeters, and the female is up to 40 centimeters. Body color from white to pale pink, narrow, cylindrical, pointed at the ends. The mouth is a pair of cuticular lips.

They live in the jejunum and ileum for about a year, they are capable of living only in the human body. At one time, the female is able to lay up to 240 thousand eggs, which are released into the external environment along with feces. Eggs in the external environment can live up to 5 years, thanks to a five-layer outer shell that protects against most environmental factors.

Developmental Biology:

• They enter the rectum through food or dirty water, and then are localized in the small intestine.
• After 21 days, the larvae hatch, penetrate the intestinal mucosa. With the blood flow they migrate through the internal organs: the liver, the right part of the heart, the lungs.
• Having entered the lungs through the pulmonary circulation, the larvae break through the alveolar capillaries and, together with coughing or exhaled air, enter the oral cavity.
• They are swallowed through the mouth and back into the digestive tract.

The entire migration period takes up to two weeks. The female becomes sexually mature after 20 days and is able to lay eggs.

Pinworm

A nematode that causes a common disease is enterobiasis. This disease is also called "disease of unwashed hands", since the eggs of the pathogen often enter the human body through dirty food and hands. Children are mostly affected. The causative agent is localized in all parts of the intestine, and the main symptom of the disease is the tooth of the anus.

Enterobius is a nematode with an elongated body and narrowed ends. Females reach a length of up to 12 millimeters, and males up to 5 millimeters.

The color of the pathogen is grayish-white. A special vesicle is located at the mouth opening from the side of the abdominal cavity, with the help of which the helminth is attached to the intestinal mucosa.

Developmental Biology:

• enter the human body with food, are localized in the lower parts of the small intestine, attached to the intestinal mucosa.
• The female becomes sexually mature at the age of 4 weeks.
• The fertilized female moves to the rectum to lay eggs.
• At night, it comes out of the anus and lays eggs in the anal folds, after which it dies.
• One female is able to lay up to two thousand eggs.

Vlasoglav

A nematode that causes the disease trichuriasis. The causative agent is considered only human, small children are especially susceptible. The habitat is the initial section of the large intestine. With a small invasion, the symptoms of the disease almost do not appear, but with a strong infection, diarrhea, vomiting, prolapse of the rectum are possible, and are also one of the causes of inflammation of the appendix.

The causative agent trichocephalus trichiurus is a helminth 3.5 to 5 centimeters long.

The main distinguishing feature is the presence of a filiform part on the front of the body, on which the mouth opening and esophagus are located. In the rear compacted part are the remaining organs of the helminth. One individual is able to live in the human body for up to 5 years.

Developmental Biology:

• Helminth eggs enter the human digestive tract through contaminated food or water.
• Once in the small intestine, the larvae hatch within a few days.
• Immediately migrate to the large intestine.
• In the thick section, they are attached to the mucous membrane with a filiform process, cutting through the mucous membrane with it. They feed on blood and tissue fluid. After 3 months they become sexually mature.
• For a day, the female whipworm is able to lay 20 thousand eggs.

A prerequisite for the maturation of an invasive egg is to stay in moist soil at a temperature of 24-30 degrees for 10-40 days. After maturation, they remain capable of infection for several months.

Flat and roundworms: differences

Differences between flatworms and roundworms:

1. Intestines- flatworms have only a mouth opening, there is no anal opening. Excrement is excreted through small tubules that penetrate the entire body of the worm and exit through the outer integument. Nematodes have a mouth and anus, the intestinal tract is through.
2. reproductive system- , with the exception of the family of trematodes Schistosomatidae - hermaphrodites. There is an opinion that reproduction in flatworms occurs cross, but self-fertilization is not excluded. Nematodes have a strict distribution of sexes with pronounced sexual dimorphism.
3. Presence of cavities- the roundworm has a primary and secondary cavity, when, as flatworms, they belong to barren animals. In the skin-muscular sac of trematodes, digestive and excretory processes and the absorption of nutrients occur.
4. Nematodes have only longitudinal muscles, which allow the worm to move exclusively in the dorsoventral direction, and flatworms also have transverse and longitudinal muscles.

• feeling of heaviness in the lower abdomen;
• nausea and urge to vomit;
• general malaise;
• frequent diarrhea.

• the helminth has a pale pink tint;

• female body length - 20-40 mm, male - 15-20 mm;
• dioecious individuals reproduce sexually.

With gastrointestinal infection and with the penetration of ascaris into the liver, clinical symptoms are expressed in the following manifestations:

1. Pain in the abdomen, accompanied by bouts of vomiting and constant nausea.
2. There is diarrhea with bloody discharge in the stool.
3. Pressure on the hepatic and bile ducts contributes to the formation of obstructive jaundice.
4. Lack of appetite and uncontrolled weight loss.

The symptoms of pulmonary ascariasis are more problematic to recognize, since clinical signs are perceived as other diseases of the respiratory system, such as bronchitis, pneumonia, etc. The presence of helminths in the lungs is accompanied by the following symptoms:

• dry paroxysmal cough and chest wheezing;
• dyspnea;
• subfebrile body temperature.

Ascariasis in the lungs, not detected in time, leads to the development of bronchial asthma.

When ascaris penetrates into the brain, a person feels severe headaches, epileptiform seizures and convulsions occur, there is a pronounced neurosis and depression.

Important! All clinical manifestations require a thorough diagnostic examination and appropriate medical treatment.

• Piperazine;
• albendazole;
• Vermox, etc.