Protozoa are parasites. Parasites are pathogenic microorganisms: main characteristics, types, clinical picture and treatment What are parasites definition

Living things in nature react to each other and enter into relationships in different ways. One such type of communication between two organisms is commensalism or freeloading. Examples of such relationships are found quite often in nature. Let's look at the brightest of them.

Definition of freeloading (commensalism)

The relationships formed between organisms that interact in nature can be symbiotic in nature. One type of symbiosis is called freeloading, where one organism benefits from the relationship while the other species receives neither benefit nor harm. There are four areas of benefit in total:

1. Nutrition.
2. Housing.
3. Transportation.
4. Seed dispersal.

Types of commensalism

Most environmental experts group commensal relationships into the following types:

• Chemical commensalism is most often observed between two species of bacteria, one of which feeds on the chemicals or waste of the other.
• Inquilinism - one animal uses the body or body cavity of another organism as a shelter or living space.
• Entoikia is a form of commensalism that occurs when one species inadvertently creates a home inside the cavity of another but has access to the outside environment.
• Phoresia occurs when one organism attaches itself to another organism for the purpose of transport.
• Sinoikia (tenancy) occurs when one living being uses another being or its dwelling as its home.

Examples of freeloading

Commensalism is a scientific term that characterizes the relationship between two living beings from different species, in which one of the organisms benefits itself, while the other, as they say, is neither hot nor cold. Often commensalism occurs between a large animal and a smaller one. Here are some examples of freeloading:

• Some shells cannot move independently and are attached to certain inhabitants of the sea, such as whales. The former benefit from being able to transport throughout the ocean. The latter receive neither benefit nor harm from this connection.
• The egret follows herds of cattle and feeds on the insects that follow them.
• The monarch butterfly extracts a toxic chemical from the milkweed plant and stores it in its body for protection from predators.
• Remora fish and shark are good examples of commensalism.

The term "commensalism"

Commensalism is the scientific term for the concept of freeloading. In terms of time, this type of relationship can be quite short, or it can take the form of a lifelong symbiosis. The term was coined in 1876 by Belgian paleontologist and zoologist Pierre-Joseph van Beneden, who originally used the word to describe the activity of companion animals that followed predators to finish their prey. The word "commensalism" comes from the Latin word commensalis, which means "sharing, at one table" (com - together, mensa - meal).

Examples of parasites are very common. Wood frogs use plants as protection. Jackals excluded from the pack will follow the tiger to steal the remains of its meal. The small fish live on other marine animals, changing color to blend in with their host, thereby gaining protection from predators.

Burdock produces spiny seeds that cling to animal fur or people's clothing. Plants rely on this method of seed dispersal to reproduce, while animals are unaffected.

Freeloading: examples of animals and plants

Commensalistic relationships are also those in which one organism forms a habitat for another. An example of freeloading in this case is the hermit crab - here a shell from a dead gastropod is used for protection. Another example would be larvae living on a dead organism.

The animal is attached to another for transport. This type of commensalism is most often found in arthropods such as insect-dwelling mites. Other examples include anemone attachment to hermit crab shells, mammal-riding pseudoscorpions, and bird-riding centipedes.

Commensal organisms can form communities within the host organism. An example of such freeloading is the bacterial flora found on human skin. Scientists debate whether microbiota is truly a type of commensalism. For example, in the case of skin flora, there is evidence that bacteria confer some protection on the host (which would be reciprocated).

Pets and commensalism

Dogs, cats, and other animals also appear to have commensal relationships with humans. It is believed that the ancestors of dogs followed hunters to eat the remains of carcasses. Over time, the "cooperation" became mutual, with humans also taking advantage of the relationship to gain protection from other predators and assistance in tracking prey.

Marine "freeloaders"

Examples of freeloading in nature are relationships between individuals of two species in which one species receives food or other benefits from the other without harming or benefiting the latter. A pilot fish swims next to a white shark. Thanks to the flat oval sucking disc structure at the top of its head, the remora fish adheres to its host's body. Both of these parasite fish feed on the leftover food of their owners. One of the best known examples of commensalism in the ocean is the relationship that exists between clones and sea anemones.

Examples of freeloading in biology are clearly shown between organisms, which is beneficial for one of them, and neutral for the other. Many cases of commensalism are surrounded by controversy, since there is always the possibility that the commensal host also benefits or is harmed in ways as yet unknown to science.

Relationships of this type are of great importance in nature, as they promote closer cooperation among species, more efficient exploration of space, and an enriched diversity of food resources.

No. 96 Sarcodaceae.

Main representatives. Dysenteric amoeba. Morphology, development cycle, laboratory diagnostics, prevention.Pathogenic effect.AMOEBA DYSENTERICAL - Entamoeba

histolytica- causative agent of intestinal (amebic dysentery) and extraintestinal amebiasis - anthroponosis.

Geographical distribution- everywhere, especially often in countries with tropical and subtropical climates.

Localization- cecum, ascending, transverse colon, as well as liver, lungs, skin, etc.

Morphological characteristics.

3. Large vegetative (f. magna) (30 - 40 µm to 60 - 80 µm) - erythrophage.

The movement of the amoeba is active, like that of the tissue form. Under special conditions (changes in intestinal bacterial flora, weakened immunity) it forms a tissue form. When the disease is cured, the erythrophage passes into the luminal and then into the precystic form. 4. Precystic form (12-20 µm), its cytoplasm is not differentiated into ecto- and edoplasm, movement is slow. 5. Cyst form (9 - 14 µm) round with 4 nuclei. Immature cysts contain oval chromatoid bodies. They are not present in mature cysts.

Development cycle. Invasive form -

The cyst enters the person through the mouth. Infection with cysts and luminal forms can be accompanied by asymptomatic carriage, more often in mid-latitudes. Pathogenic effect.

Pathogenic forms cause intestinal ulcerations. Complications of amebiasis: intestinal bleeding and the development of abscesses in the liver. Rarely, an abscess may develop in the lungs, brain, skin, or other organs.

Source of infection - sick person and carrier.

Diagnostics.

Detection of tissue and large vegetative forms in a smear of freshly collected feces. The presence of luminal forms and cysts is not enough to diagnose amoebiasis. These forms usually indicate carrier status.

Immunological diagnostics are possible.

Prevention:

a) public - identification and treatment of patients and carriers; b) personal - observing the rules of personal hygiene (washing hands, vegetables, fruits, boiling water).

The real ones, which are actually in another organism, are excreted in its feces, where they can be found (house fly larvae);ωύρύω False (imaginary), which can accidentally end up in feces brought, for example, for analysis (flies can lay eggs on them, and larvae quickly hatch from them).

1. Depending on the number of probable hosts:έτερος Euryxenni (from Greek.- wide) - those that have a wide range of hosts (ixodid ticks, mosquitoes); Heteroxenni (from Greek.

- different, different) - those that undergo complex development cycles at the expense of several hosts. Yes, dog tick

passes

three stages of development: larva, nymph, imago - and at each stage it has its own host.

External - live on the outer integument of the host (lice, fleas, mosquitoes);

Cutaneous - live in the thickness of the skin, and partly on its surface (scabies);

Cavity - live in a cavity that communicates with the external environment - in the external auditory canal, in the nasal cavity (Wohlfart fly larvae).

Cavity - live in the body cavities of internal organs (ascaris, gostrik);

Tissue - in muscle, nervous tissues (Trichinela);

Internal octopuses (sporophores, flagellates).

The most common diseases are:

Causes

The cause of the disease is T. solium (pork tapeworm). People become infected by eating improperly cooked pork. Lack of hygiene is also risky.

If a person swallows an egg, the stomach and duodenum release larvae, which enter the bloodstream through the intestinal wall and spread throughout the body. In the place where the larva attaches (for example, in the muscles or in the human brain), it turns into a cysticercus, which matures within 2-3 months and lives for several years.

Diagnostics

Treatment

In the case of ophthalmic cysticercosis, surgical removal of the cysticerci can be used.

Manifestations

Symptoms of the disease vary depending on the location of cysticerci in the body. Neurocysticercosis, in which cysticerci are found in the human brain and spinal cord, has the following symptoms:

• epileptic seizures;
• intracranial hypertension (increased intracranial pressure);
• mental disorders.

Brain toxoplasmosis – neurotoxoplasmosis

Treatment

Toxoplasmosis in immunocompetent (with an intact immune system) and non-pregnant women does not require specific treatment. As an alternative, symptomatic therapy is chosen (relief of individual symptoms - such as pain, fever, etc.). In certain cases, drugs of the antiprotozoal group are administered - in particular, Pyrimethamine, possibly in combination with Sulfadiazine (a group of sulfonamide chemotherapy drugs). In rare cases, a decision is made to surgically remove the localization or abscess.

Manifestations

Symptoms of cerebral toxoplasmosis are quite varied and include the following types:

• epileptic seizures;
• intracranial hypertension;
• headache;
• vomiting/nausea;
• anxiety;
• apathy or irritability;
• disturbance of consciousness;
• focal neurological symptoms (impaired speech, walking, sensations, feelings);
• cranial nerve palsy;
• hemiparesis (paralysis of a limb on one side);
• mental disorders;
• mental changes (slow reaction, changes in behavior, personality disorders);
• visual impairment.

Some experts suggest a connection between the latent form of Toxoplasma and the effects of T. gondii on the human nervous system, for example:

• changes in brain hormone production;
• schizophrenia;
• increased irritability and aggressiveness;
• symptoms of cerebral allergy;
• increased sexual activity while decreasing the social and emotional depth of relationships (superficial relationships);
• increased selfishness and resentment;
• decreased social intelligence (communication disorders, lack of social tact);
• decreased sense of self-preservation;
• phobias of subjectively or objectively dangerous places and situations;
• increasing the likelihood of road accidents.

Elevated levels of testosterone, dopamine, inflammatory markers, and other brain responses to toxoplasmosis may also increase aggression in the affected person or trigger the development of schizophrenia if a predisposition is present.

However, other studies have not demonstrated an association of the risk of motor vehicle accidents, schizophrenia, violent and nonviolent behavior change, suicide attempts, decreased responsiveness and short-term memory, and other symptoms with toxoplasmosis. The results of many subsequent studies were also largely negative.

Echinococcosis

• cystic echinococcosis (caused by E. granulosus);
• alveolar echinococcosis (caused by E. multilocularis).

There are 2 less common forms - polycystic and cystic echinococcosis.

The disease has a relatively long incubation period. Signs depend on the location and size of the cysts. Alveolar disease usually begins in the liver, but can spread to other parts of the body, such as the lungs or brain.

Forecast

Manifestations

Signs of the disease are largely reminiscent of brain cancer and include the following symptoms:

• dizziness;
• cephalgia;
• epileptic seizures;
• intracranial pressure.

Diagnostics

Cysts are imaged using ultrasound or CT. An ELISA test can also be used to detect antibodies and antigens.

According to doctors, the mortality rate during infection is more than 98%.

Initially, the person suffers from fever, nausea, vomiting, stiff neck and headache. Death occurs within 5-7 days. The disease does not spread from person to person.

Helminths

Cystidicola farionis

Trienophorus nodulosus

Diphyllobothrium latum

• thoroughly clean the fish;
• cut into 1 cm pieces;
• boil for 30-40 minutes.

To salt infected fish, it is necessary to keep it for 10-12 days at low temperatures, and then leave it for 7-8 days at room temperature in a saline solution. Salt must be added in an amount of at least 3 parts by weight of the fish. Careful preparation and handling of infected fish does not guarantee that infestation will not occur. That is why, to avoid the development of serious diseases, you should not include contaminated fish meat in your diet.

Russian cuisine does not have dishes with raw fish. But in this case we should not forget about the herring. This type of product is quite popular due to its taste and low cost. Not every manufacturer follows the technology for making herring, so contamination cannot be completely ruled out when consuming this product.

Among the dangerous helminthic infestations, one can highlight ink-spot disease, which infects fish that contain the causative agent of post-diplostomosis in their bodies. This disease is not very dangerous, but experts recommend refraining from eating fish that have dark spots on the body.

How to distinguish infected fish

A product that is unfit for consumption has certain differences, knowing which you can protect yourself from infection:

• Infected fish have damaged muscle structures. When pressed, the resulting hole does not level out.
• The pupils of the fish are cloudy, and the mucous membrane is usually dry.
• The belly of the fish is saggy and swollen.
• The gills acquire a characteristic swampy hue, and the internal organs of the fish have a foul odor during cutting.
• The anus protrudes above the main body of the fish and viscous, cloudy mucus flows out of it.

When preparing contaminated fish, the broth has quite specific characteristics. The broth is usually cloudy. There is no fatty film on its surface. Instead, the broth contains a mass of dark particles and flakes of unknown origin.

source

Less common are stellate, cubic, tetrahedral, O- and C-shaped forms of microorganisms. It is this factor that determines the abilities and capabilities of bacteria. We are talking about their mobility, adhesion to the surface, and absorption capabilities. Among the unchanged cellular structures, one can distinguish ribosomes, nucleoids, and CPMs (cytoplasmic membranes).

The average size of a common bacterium varies from 0.5 to 5 microns. The largest representative is Thiomargarita (750 microns).

Main characteristics

Irritability and modes of movement

A separate type of movement is sliding. This is characteristic of those microorganisms that are not equipped with flagella; it is assumed that they secrete a kind of mucus that helps push the cell through. The cell walls of microorganisms contain fibrillar filaments, which cause movement.

Bacteria have unique abilities to immerse themselves in liquid. They can also float to the surface freely. At the same time, they completely change their density on their own.

Energy form of metabolism

Each type of bacteria has unique properties and capabilities. They are so individual that their classification is enormous. There are several main ways to release energy:

Bacteria, according to the degree of impact on the human body, are of the following types:

• Safe - do not cause diseases in the human body, despite the fact that they pose a danger to plants and animals.
• Conditionally pathogenic (saprophytes, symbionts) - do not cause pathological processes under normal conditions. Hypothermia, a decrease in the body's defenses, and the proliferation of pathogenic microflora can provoke the development of the disease.
• Pathogenic (bacilli, cocci) – pathogenic bacteria are the cause of the development of acute respiratory infections, sore throats and other diseases that are quite easy to treat.
• Extremely dangerous - they lead to death in a fairly short period. They cause the development of pandemic and epidemic outbreaks of diseases (tetanus, cholera, botulism).

Features of the existence of bacteria

In connection with these factors, bacteria are divided into:

1. Obligate (viruses, rickettsia) - capable only of intracellular existence.
2. Facultative - they exist outside the host, synthesize organic substances, and enter suspended animation (encapsulated).

Sources of infection

Protozoan pathogenic microorganisms can be transmitted to humans from animals (zoonotic) or from infected people (anthropotic). There are several main routes of transmission, among which proto-ozonosis should be noted. It represents the transmission of bacteria to humans from arthropods and insects. Infections can also live on non-living objects. This route of transmission is called sapronotic. Bacteria that cause flora diseases are not harmful to humans, but despite this they can cause serious poisoning.

Despite the fact that bacteria are the simplest microorganisms, they are much more dangerous than helminths. This is due to the fact that they have unlimited reproduction capabilities. Pathogenic bacteria are not compatible with health. More than 2 kg of various microorganisms live in the human body, which constitute the microflora of the body. We are talking only about the intestines!

How to defeat pathogenic bacteria

What worms do humans have: types and varieties

For timely detection and effective disposal of worms, their species should be taken into account. From the classification you can find out what worms are in the human body.

Some worms live and develop in the intestines, others penetrate the bile ducts or migrate in the blood vessels, and others find optimal conditions for their life in the liver, lungs or brain.

Biological characteristics determine the following types of worms:

• roundworms or nematodes;
• tape or cestodes;
• flukes, whose scientific name is trematodes.

Geohelminth eggs undergo a mandatory stage of maturation in the soil; without this, they are not able to infect humans and cause disease.

For the full development of biohelminths, a change in two or more intermediate hosts is required. It happens that before they penetrate the human body, worms go through their stages of development in the body of animals belonging to certain species.

Contagious types of worms do not have additional hosts and do not require special development conditions. Their mature larvae are released into the external environment from the human body.

Roundworms are most widespread among humans. There are more than 24 thousand species. These worms got their name from the rounded shape of their body in cross section. The most common roundworms in humans are roundworms, pinworms, whipworms and trichina. The anterior and posterior ends of the body of nematodes are pointed and have a rounded shape. This is the main distinguishing feature of these worms.

The most dangerous of all nematodes for humans are whipworm and trichina. The favorite habitat of the whipworm is a thin worm 3-4 cm in size, the cecum. Invading the mucosa, it causes local inflammation, accompanied by a picture of appendicitis.

Flukes or trematodes

These worms also have a flat body shape, but unlike cestodes roundworms, one of their life cycle stages takes place in the body of an intermediate host. Adults, which are divided into tapeworms and tapeworms, live in the body of vertebrates, including humans.

The body of tapeworms is divided into segments. At the head end there are suckers - scolex, with the help of which the worms are fixed to the intestinal mucosa. The segments of the worm's body following the head are essentially the growth zone. Tapeworms absorb all nutrients through the body surface. It is saved from digestion by pancreatic and gastric juices by a special enzyme - antikinase. Tapeworms have two suction grooves, tapeworms have four suckers on their heads and reach 18 meters in length.

source