What are parasites: types and classification

Knowing the ways in which parasites enter the body, it is possible to take preventive measures in contact with possible sources of infection. What helminths are, like intestinal parasites, is known to many. However, the common man is less aware of the species that live in the circulatory system, subcutaneous lymph, muscles, brain and internal organs.

All types of parasites in the human body are classified into representatives: protozoa, flat and round worms, arthropods and their larvae.Viruses, pathogenic bacteria and fungi can be classified as parasites, but are isolated in a separate group. Infectious diseases are divided into: viral, fungal, bacterial and parasitic. The classification of human parasites includes - a unique species of fish (common vandelia), capable of penetrating the human urethra (random host).

Parasitism and its types

Who are parasites? These are organisms that live to the detriment of another individual, and are not genetically related to it and enter into antagonistic relationships, that is, they interfere with life. The concept of parasitism should not be extrapolated to microorganisms living in the body without causing particular harm to it. In nature, there are plant and animal parasites, depending on the type of host. During the functioning of this way of life, the system of parasites and hosts is constantly operating. The task of the first: to live from the second without killing him for a long time.

Classification of parasites by species:

1. Localization of the site: external and internal parasites (exo- and endoparasites).
2. Lifestyle: constantly parasitic (obligatory) and free forms that under certain conditions begin to exist to the detriment of another organism (optional parasites).
3. By time of contact with host: temporary and permanent parasites (immobile and periodic).

In the food chain, animal parasites are usually second- or third-order consumers because they feed on herbivores or carnivores. The way the parasite feeds deprives the host of nutrients and / or leads to cell and tissue destruction. Antagonism with the host often occurs because dangerous residents release toxic metabolic products. This leads to certain symptoms (allergies, disorders of the digestive system, signs of damage to various internal organs).

Viruses

Viruses are intracellular parasites of protein-genetic structure. Due to the material in the cell, they reproduce themselves. The virus is a mandatory parasite.

According to the classification, depending on the type of genetic material, viruses containing RNA and DNA are isolated. Intracellular agents of the first group include:

1. Enteroviruses. They multiply in the digestive tract, causing problems in various human organs.
Rhinoviruses. Causes of ARVI.
2. Influenza, rabies and tick-borne encephalitis viruses.
Papilloma virus.

The second group includes: adenoviruses (causing acute respiratory infections), herpes, and smallpox pathogens.

Viruses, entering the target cell, subordinate their processes to themselves, integrate into genetic material or localize in the cytoplasm, and then multiply. Then the death cell occurs as a result of lysis, apoptosis or distortion of the membrane structure. Some representatives (papilloma viruses, Epstein-Barr virus) are capable of causing cell degeneration into malignant ones.

How viruses penetrate:

1. In the air.
2. Through the gastrointestinal tract when drinking water and eating food.
3. Through the skin and outer mucous membranes, like the conjunctiva of the eye.
4. Using arthropod vectors (insects, ticks).
5. As a result of the use of non-sterile medical devices (syringes, pipettes).

Each virus is adapted to a specific cell, distinguishing the target with the help of receptors.

Bacteria

Among bacteria, rickettsiae, intracellular parasites, occupy a special position. These are the most primitive representatives that resemble viruses. In humans, these microorganisms cause: typhus, tick-borne rickettsiosis, spotted fever on Rocky Mountain. People become infected with rickettsiae by the stings of ticks, fleas, and lice.

Other intracellular chlamydia parasites cause one of the most common sexually transmitted diseases (chlamydia) and cause severe eye inflammation, neonatal pneumonia and enteritis.

Dangerous bacteria include:

1. Salmonella is the cause of typhoid fever.
2. Tetanus' wand.
3. A pale spirochete that causes syphilis due to a difficult diagnosis of the disease, leading to a delay in treatment.
4. Pneumococci, which can cause pneumonia and, less commonly, bacterial meningitis.
5. A bacillus of tuberculosis, which may not manifest for a long time and then turn into an open form.
6. Escherichia coli because of its ability to acquire antibiotic resistance. It causes gastroenteritis, rarely meningitis and urinary tract infection.

External parasites such as Staphylococcus aureus are known to cause a wide range of skin infections. The most dangerous consequences of its action: pneumonia, meningitis, osteomyelitis, endocarditis, severe shock due to exposure to bacterial toxins and sepsis (in everyday life it is called blood poisoning).

Mushrooms

Disease-causing fungi - human parasites are better protected from drugs than bacteria. The most common fungal disease is candidiasis (thrush), localized on various mucous membranes with a weakened immune system. Fungi of the genus Candida live in the body of any healthy person and cause tangible damage only if the protective function fails. Conditionally pathogenic bacteria and fungi are a borderline group of microorganisms between nonpathogenic and pathogenic categories. Therefore, they are generally not classified as parasites.

Pathogenic mycelial fungi are human parasites that often cause diseases of the outer covering:

1. Keratomycosis. The reproduction of the fungus occurs in the keratinized zone of the epidermis or on the hair cuticle (trichosporia nodosum, versicolor versicolor).
Dermatophytosis. Pathogens affect not only the epidermis, but also the dermis, nails and hair (lichen, scabies).
2. Deep mycoses. Damage to the skin and nearby tissues, as well as internal organs. These include histoplasmosis - a severe systemic fungal disease and aspergillosis - damage to the mucous membranes and skin caused by aspergillosis.

The classic sources of bacterial and fungal infections are sick people, animals, soil, dirty water and food.

Protozoa

Protozoa are another cellular parasite along with bacteria and fungi. Which protozoan parasites of a person are isolated depending on the systematic position?

1. Some species of amoebae are facultative parasites. The most famous is the dysenteric amoeba, which enters the human body in the form of a cyst (at rest). The pathogen enters the colon (luminal form), then penetrates the mucosa and affects various internal organs through the bloodstream. Amoebae are aquatic organisms, so the main source of infection is dirty water. Acanthamoeba keratitis is a rare eye disease called acanthamoeba keratitis, which has become more common due to the growing popularity of contact lenses.
Whips (Leishmania, Giardia, Trichomonas). Trichomoniasis is the most common disease of the genitourinary system, dangerous due to its complications (infertility, prostatitis, premature birth, etc. ). Apicomplexes (sporozoi). With the exception of colpodellids, the group includes only obligatory parasites (Toxoplasma, Plasmodium malaria, Cryptosporidium, Coccidia, sarcocysts). Sporozoic cysts enter the body after being bitten by insects, eating infected animals, or drinking water.
2. Ciliates. For humans, balantidia is dangerous, causing diarrhea and ulcers on the intestinal wall as a result of activity in the colon. Ciliates are the largest pathogenic unicellular organisms.

The simplest human parasites cause protozoal infections (protozoa). Which parasites live in the human nervous system among protozoa? For example, the causative agents of toxoplasmosis and cerebral malaria. Among amoebae, the facultative parasite Neglerius Fowler is capable of infecting the nervous system.

Multicellular

Multicellular parasites include flatworms, roundworms, arachnids and insects. The former, as a rule, occur inside a person (in various systems and internal organs), and certain species migrate or penetrate (ridges, larvae of Gnathostoma spinigerum and ankylosis, schistosomes) into the subcutaneous layer. Worms are the common colloquial name for all worms that cause helminthiases.

Common diseases caused by flatworms

Trematode group (digenetic flukes):

1. Opisthorchiasis. Causes: types of liver flukes, for example, feline and Siberian flukes. The infection occurs as a result of eating infected river fish, poorly heat treated.
Fascioliasis. The causative agent of liver and giant flukes. Infection occurs by consuming contaminated water or coastal grass.
2. Schistosomiasis. The causative agents of schistosomes (especially blood flukes) live mainly in hot climates. They penetrate the skin by contact with water.
3. Paragonimiasis. The cause of the disease is the pulmonary fluke, which is found in hot climates. It is a dangerous worm and poorly treated thermally freshwater crab or crab.

The life cycle of parasites from the trematode group is complex, including several larval and gastropod stages as intermediate vectors. Flakes are animal parasites of vertebrates, acting as temporary and permanent hosts. Individual stages of larvae can develop without fertilization. Flukes devices for securing and feeding inside the host are pumps.

Tapeworms are obligate parasites of the small intestine of man. Their body consists of segments (proglottids), which occasionally break and come out along with the fertilized eggs. The life cycle stages of tapeworms necessarily include a fin (blister worm), which occurs in a temporary owner. The permanent host swallows Finca, which develops into a narrowed form (for adults). The structural features of tapeworms are the absence of the digestive system and the absorption of nutrients over the entire surface.

Most common:

1. Bovine tapeworm (unarmed tapeworm) causes the disease teniarinhoza. The infection occurs through beef, whose muscles are Finns, and is formed in the body after the animals have swallowed eggs with food.
2. Swine tapeworm (armed tapeworm) is the cause of cysticercosis (Finnish phase) and teniase (adult). In addition to the breast, the helminth is also equipped with a hip edge. A person can simultaneously perform the function of indirect and permanent owner.
3. Broad tapeworm causes diphyllobotriasis. Medium hosts are copepods and fish. A person can become infected with insufficiently salted caviar and poorly cooked or fried freshwater fish.

Parasites feed on blood and tissue (flukes) or digested food (tapeworms).

Roundworms

What are the common types of parasites in humans roundworms (nematodes)?

1. Ascaris. Ascariasis involves the stage of migration (larvae) and intestines (adults). The larva penetrates the wall of the small intestine, moves to the lungs, bypassing the liver and heart, successively going through the stages of molting. It enters the oral cavity, is swallowed again and becomes an adult in the small intestine.
Pinworm. The causative agent of enterobiasis feeds in the final and initial zone of the small and large intestine, multiplies in the ileum. Females lay eggs in the anal folds, causing severe itching.
2. Vlasoglav is the cause of trichocephaly. These parasites in the human body attack the mucosa of the initial part of the colon and feed on tissue fluid and blood.
3. Trichinella causes the dangerous disease trichinosis. In severe cases, the nervous system is damaged. These are real killers, whose larvae penetrate the wall of the small intestine and are carried throughout the body. They mainly enter the striated muscles, can penetrate the eyes, causing pain and swelling of the face, into the lungs, leading to coughing. So far, no cure has been devised for complete recovery.
Toxocara. Distinguish between larva (occurs more often) and imaginal (intestinal) toxocariasis. Invasion is characterized by the severity of allergic reactions. The larvae spread throughout the body, entering the tissues, encapsulating and forming granulomas.
4. Hookworm is more common in tropical and subtropical regions. In addition to ankylosis infection, the worms secrete proteolytic enzymes inside the gut that destroy the walls and reduce blood clotting. Parasites inside a person appear as a result of the entry of larvae through the skin from contaminated water.
5. Escherichia coli and related species are tropical parasites. The disease they cause, strongyloidosis, can be asymptomatic for decades. With reduced immunity, worm carriers are at high risk of death (60-85%).
6. Rishta is a subtropical helminth that causes dracunculia. The larvae penetrate the intestinal wall. Females reach the subcutaneous layer and when the host is in the water, they expel the larvae through the skin. The temporary host is copepod cancer.

The characteristics of parasite habitats affect the way they enter the body: contact with contaminated water or land, with the carriers of the larval stages that inhabit them. Many representatives of roundworms have no indirect hosts and belong to geohelminths. Infection with them mainly occurs with contaminated water, unwashed hands, fruits or vegetables, as well as consumption of wild animal meat.

Treatment and terrible consequences of helminthiasis

An important way to diagnose helminthiasis is a blood test. Eosinophils (a type of white blood cell) found in high concentrations, along with other signs of infection, indicate the presence of worms and a number of pathogenic protozoa in the body. How are helminthiases treated? Medications are used to relieve symptoms and specific treatment. Antiallergic (desensitizing) and detoxification therapy is used. Basically, the drugs are given by infusion (using a dropper), sometimes injections are used:

1. A drug that replaces plasma and removes the effects of toxins.
2. Isotonic glucose solution and saline.
3. Vitamins C and B6.
4. Sodium bicarbonate (soda), calcium chloride or gluconate.
5. Preparations used at elevated temperatures.
6. Hormonal drugs are used in difficult situations (with hepatitis or allergic myocarditis). Potassium intake is combined with them.
7. Medications for heart failure and edema.

There is evidence that certain parasitic worms, such as pigmented tapeworms, can cause cancer. Larval stem cells can degenerate into carcinogens. Parasites can indirectly cause cancer by weakening the immune system. Interesting data were obtained in studying the effect of trematodes affecting the liver. As a result of exposure to waste flukes, ordinary cells can turn into cancer cells. Parasites are mainly localized in the digestive system, but their larvae can penetrate various internal organs. For example, in the kidneys (echinococcosis, schistosomiasis), heart muscle (cysticercosis, rod disease), liver (echinococcosis). Parasitic worms in humans often affect the nervous system. Known cysticercosis, echinococcosis, alveococcosis and schistosomiasis of the brain.

Arthropods

The order of insects includes such well-known ectoparasites as fleas, bed bugs, two-way bloodsuckers. Unlike lice, they are temporary parasites, that is, they live constantly with the help of the host. Arthropod parasites from arachnids include the well-known mange mite. Mating of males and females occurs on the surface of the epithelium. The parasites in the human body then lay eggs in the keratin layer of the skin, causing severe itching. Many people know what ixodid ticks are. These are arthropod parasites from the order of arachnids, including the most famous representative of the taiga tick - a carrier of dangerous infections (tick encephalitis, Lyme disease). Among the two-way bloodsuckers are: non-malignant and malarial mosquitoes, mosquitoes, flies, biting mussels, horseflies and real flies. These arthropod parasites can cause a strong allergic response and are also carriers of dangerous viral and bacterial infections. Some flies, especially gadflies, deposit larvae under human skin, causing miasma. The larvae are able to penetrate the body.