What are parasites: species and classification

Knowing the ways of penetration of parasites into the body, it is possible to take preventive measures in case of contact with possible sources of infection. What are helminths, as intestinal parasites, is known to many. However, the average person is less familiar with 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 they are divided into 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 (accidental host).

Parasitism and its types

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

Classification of parasites by species:

1. Localization sites: external and internal parasites (exo- and endoparasites).
2. By way of life: permanently parasitic (obligatory) and free-living forms, which under certain conditions begin to exist at the expense of another organism (optional parasites).
3. At the time of contact with the host: temporary and permanent parasites (stationary 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 the destruction of cells and tissues. Host antagonism often occurs because dangerous occupants secrete toxic metabolic products. This leads to certain symptoms (allergies, digestive disorders, signs of damage to various internal organs).

Viruses

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

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

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

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

Viruses, entering the target cell, subordinate its processes to themselves, integrate into the genetic material or are localized in the cytoplasm, and then replicate (multiply). Then cell death occurs as a result of lysis, apoptosis or distortion of the membrane structure. Some representatives (papillomaviruses, Epstein-Barr virus) are able to cause cell degeneration into malignant.

How viruses penetrate:

1. Airy.
2. Through the gastrointestinal tract when you drink water and eat food.
3. Through the skin and outer mucous membranes, such as 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, differentiates the target with the help of receptors.

Bacteria

Among bacteria, rickettsiae, intracellular parasites, occupy a special place. These are the most primitive representatives that look like viruses. In humans, these microorganisms cause: typhus, rickettsiosis transmitted by ticks, spotted fever in the Rocky Mountains. People become infected with rickettsiae through the bites of ticks, fleas, lice.

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

Dangerous bacteria include:

1. Salmonella is the cause of typhoid fever.
2. Tetanus rod.
3. Pale spirochete, which causes syphilis due to a difficult diagnosis of the disease, which leads to a delay in treatment.
4. Pneumococci that can cause pneumonia and less commonly bacterial meningitis.
5. Tuberculosis bacillus, which may not develop for a long time and then turn into an open form.
6. Escherichia coli due to its ability to acquire antibiotic resistance. 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 activity: pneumonia, meningitis, osteomyelitis, endocarditis, severe shock due to exposure to bacterial toxins and sepsis (in everyday life it is called blood poisoning).

Mushrooms

Fungi that cause disease - 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 every healthy person and cause significant damage only if the protective function fails. Conditionally pathogenic bacteria and fungi are a border group of microorganisms between non-pathogenic and pathogenic categories. Therefore, as a rule, they are not classified as parasites.

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

1. Keratomycosis. The reproduction of fungi occurs in the stratum corneum of the epidermis or on the cuticles of hair (trichosporia nodosum, versicolor versicolor).
2. Dermatophytosis. Pathogens affect not only the epidermis, but also the dermis, nails and hair (ringworm, scabies).
3. 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 aspergillus.

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

Protozoa

Protozoa are another single-celled parasite along with bacteria and fungi. What protozoan parasites in humans 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 (form at rest). The pathogen enters the large intestine (luminal form), then penetrates the mucosa and affects various internal organs with blood flow. Amoebae are aquatic organisms, so the main source of infection with them is dirty water. Acanthamoebic keratitis is a rare eye disease called acanthamoebic keratitis, which has become more common due to the growing popularity of contact lenses.
2. Bulls (Leishmania, Giardia, Trichomonas). Trichomoniasis is the most common disease of the genitourinary system, dangerous for its complications (infertility, prostatitis, premature birth, etc. ).
3. Apicomplexes (sporozoites). With the exception of colpodelids, the group includes only obligate parasites (Toxoplasma, Plasmodium malaria, Cryptosporidium, Coccidia, sarcocysts). Sporozoic cysts enter the body after being bitten by insects, eating infected animals, or drinking water.
4. Cliati. For humans, balantidia is dangerous, provoking diarrhea and ulcers in 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). What parasites live in the human nervous system among the protozoa? For example, the causative agents of toxoplasmosis and cerebral malaria. Among amoebae, the optional parasite Neglerius Fowler is capable of infecting the nervous system.

Multicellular

Multicellular parasites include flatworms, roundworms, arachnids and insects. The former, as a rule, settle inside humans (in various systems and internal organs), and some species migrate or penetrate (larvae, larvae of Gnathostoma spinigerum and hookworms, schistosomes) into the subcutaneous layer. Worms are the common name for all worms that cause helminthic infestations (helminthiasis).

Common diseases caused by flatworms

Trematode group (digenetic flukes):

1. Opisthorchiasis. Causes: types of liver flukes, such as feline and Siberian flukes. The infection occurs as a result of eating infected river fish, poorly heat-treated.
2. Fascioliasis. Caused by liver and giant flukes. Infection occurs through the consumption of contaminated water or coastal grass.
3. Schistosomiasis. The causative agents of schistosomes (particularly blood methyl) live mainly in hot climates. They penetrate the skin on contact with water.
4. Paragonimiasis. The cause of the disease is pulmonary methyl, which occurs in hot climates. Infected with worms and poorly treated thermally freshwater cancer or cancer is dangerous.

The life cycle of the parasite from the group of trematodes is complex, including several larval stages and gastropods as intermediate carriers. Methyls are animal parasites of vertebrates that act as temporary and permanent hosts. The individual stages of the larvae are able to develop without fertilization. Flukes fixing and feeding devices inside the host are shoots.

Tapeworms are obligate parasites of the human small intestine. Their body consists of segments (proglottids), which periodically break off and come out together with the fertilized eggs. The stages of the life cycle of tapeworms necessarily include a fine (blister), which is formed in a temporary owner. The permanent host swallows the Finn, who develops into a pointed (adult) form. The structural features of tapeworm are the lack of digestive system and the absorption of nutrients from the entire surface.

Most common:

1. Beef tapeworm (unarmed tapeworm) causes tapeworm disease. Infection occurs through the meat of cattle, the muscles of which are contained by the Finns, formed in the body after the animals swallow eggs with food.
2. Swine tapeworm (armed tapeworm) is the cause of cysticercosis (Finn's stage) and tapeworm (adult). In addition to the shoots, the helminth is equipped with a hook edge. A person can simultaneously perform the function of intermediate and permanent owner.
3. Broad tapeworm causes diphyllobotriasis. Intermediate hosts are copepods and fish. One can become infected through insufficiently salted caviar and poorly cooked or fried freshwater fish.

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

Roundworms

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

1. Ascaris. Ascariasis includes migratory (larval) and intestinal (adult) stages. The larva penetrates the wall of the small intestine, moves into the lungs, bypassing the liver and heart, passing successively through the stages of molting. It enters the oral cavity, is swallowed again and becomes an adult in the small intestine.
2. Blade. The causative agent of enterobiosis feeds in the terminal and initial areas of the small and large intestines, multiplies in the ileum. Females lay eggs in the anal folds, causing severe itching.
3. Hair loss is the cause of trichocephaly. These parasites in the human body invade the lining of the initial part of the colon and feed on tissue fluid and blood.
4. 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 transmitted to the body. Most often they get into the striated muscles, can penetrate the eyes, causing pain and swelling of the face, lungs, leading to coughing. So far, no cure has been devised for complete recovery.
Toxocara. Distinguish between larva (more common) and imaginal (intestinal) toxocariasis. The invasion is characterized by the severity of allergic reactions. The larvae spread throughout the body, entering the tissues, encapsulating and forming granulomas.
5. Hookworm is more common in the tropics and subtropics. In hookworm infection, the worms inside the gut secrete proteolytic enzymes that break down the walls and reduce blood clotting. Parasites inside a person appear as a result of the introduction of larvae through the skin from contaminated water.
6. Escherichia coli and related species are tropical parasites. The disease they cause, strongyloidiasis, can be asymptomatic for decades. With reduced immunity, worm carriers are at high risk of death (60-85%).
7. Rishta is a subtropical helminth that causes dracunculiasis. The larvae penetrate the intestinal wall. The 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 peculiarities of the habitat of parasites affect the ways in which they enter the body: contact with contaminated water or soil, with carriers of larval stages inhabiting them. Many roundworms have no intermediate hosts and belong to geohelminths. Infection with them occurs mainly through contaminated water, unwashed hands, fruits or vegetables, as well as through the 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 helminthiasis treated? Medications are used to relieve symptoms and specific treatments. Antiallergic (desensitizing) and detoxification therapy is used. Generally, medicines are given by infusion (using a dropper), sometimes injections are used:

1. A drug that replaces plasma and eliminates 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 some parasitic worms, such as pygmy tapeworm, can cause cancer. Larvae stem cells can degenerate into cancerous ones. Parasites can indirectly cause cancer by weakening the immune system. Interesting data were obtained in the study of the effect of trematodes affecting the liver. As a result of exposure to waste flukes, ordinary cells can turn into cancer cells. The parasites are localized mainly in the digestive system, but their larvae are able to penetrate various internal organs. For example, in the kidneys (echinococcosis, schistosomiasis), heart muscle (cysticercosis, hookworm 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, bedbugs, blood-sucking biplanes. Unlike lice, these are temporary parasites, that is, they live intermittently with the help of the host. Arthropod parasites of the arachnids include the well-known scabies. The mating of males and females occurs on the surface of the epithelium. The parasites in the human body then lay their eggs in the keratin layer of the skin, causing severe itching. Many people know what ixodic ticks are. These are parasites of arthropods of the order of arachnids, including the most famous representative of the taiga tick - a carrier of dangerous infections (tick-borne encephalitis, Lyme disease). Among the blood-sucking biplanes there are: non-malarial and malarial mosquitoes, mosquitoes, flies, bite flies, horse flies 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 reptiles, lay larvae under human skin, causing myiasis. The larvae are able to penetrate the body.