Types of parasites in the human body: classification, description, methods of control and treatment.

parasites in the human body

There are zoological and ecological classifications of parasites.

Zoothe classification establishes the belonging of the parasite to certain systematic categories: type, class, order, family, genus.

Environmentalclassifications are based on lifestyle characteristics of the parasite.

  • specific parasites.they parasitize only in one species of animals (pinworms, pygmy tapeworm, louse);
  • nonspecific parasites- they parasitize on different types of animals (mosquitoes, tapeworm, trichinella).

According to the location of the parasite in the host organism:

ectoparasites-parasitizes the external integument of the host (blood-sucking arthropods);

endoparasites- the habitat is the host organism:

  • in the abdominal organs associated with the external environment (digestive, respiratory and genitourinary systems): ascaris, pulmonary fluke;
  • in tissues (musculoskeletal system, subcutaneous fat) - guinea worm, trichinella;
  • intracellular (malarial plasmodium);

transition shapes.For example, in the stratum corneum of the epidermis, the itch parasitizes the itch, which breathes atmospheric oxygen.

According to the degree of connection between the development cycle of the parasite and the host organism:

  • permanent parasites- the entire cycle of development takes place on the body of one owner (trichomonas, scabies, lice);
  • temporary parasites- only part of the development cycle takes place in the host organism (hematophagous insects, worms).

Based on the number of hosts that change regularly in the development cycle:

The host is a living organism used by the parasite as a source of food and habitat.

Host classification

The hosts are divided intoend, intermediateYreservoir.

Final (basic, definitive)- hosts in whose organism the parasite is at the stage of sexual maturity or reproduces sexually (malarial mosquito for plasmodium malaria, man for sexually mature porcine tapeworm).

Intermediate- hosts in whose body the parasite is in the larval stage or reproduces asexually (humans for the malarial plasmodium; pigs, wild boars for tapeworms).

reservoir- hosts that are not obligatory in the life cycle of the parasite, but once in the organism of which the parasite does not die, although it does not receive further development. The parasites accumulate in the reservoir host. When the reservoir host is eaten by the definitive host, the parasite completes its development in its body. For example, in the human intestine, a wide tapeworm can parasitize. Man is the supreme master for him. There are two intermediate hosts in the development cycle: the first is the cyclops crustacean, the second is many species of fish. But predators, for example, pike, can eat non-predatory fish. In this case, the helminth larvae do not die, but accumulate in the muscles of the pike and it becomes a reservoir host.

Thus,the host organism is a kind of habitat for the parasite.The doctrine of the host organism as the habitat of the parasite was developed for the most part by academician E. N. Pavlovsky.The totality of all organisms living simultaneously in any organism is called a parasitocenosis.

Classification of parasites

According to the degree of need of the species to lead a parasitic lifestyle:

  • false parasitism- individual individuals of a free-living species accidentally enter the body of another species, where they remain viable and cause disturbances in the normal life of the host. After a brief parasitism in the host organism, the false parasites die or are released into the environment. For example, coprophilic amoeba can live in feces. When the stool dries, it becomes encysted. Coprophilic amoeba cysts can accidentally enter the human intestine. Cysts usually pass through the intestines and are excreted into the external environment with feces. In some cases, amoebas in the human intestines emerge from the cysts and become parasitic for a short period of time, causing acute digestive disturbances.
  • facultative parasitismsuggests the possibility that a species leads both a free and a parasitic way of life. With this form of parasitism, free-living species, accidentally entering the body of another species, temporarily use it as a habitat and food source. Compared to false parasites, facultative parasites spend more time in the host organism. An example of facultative parasitism is the free-living amoeba of the genusNaegleriaYAcanthamoeba. Negleria and Acanthamoeba live in water bodies that receive sewage. Entering the human body through the mouth or skin wounds, they can cause severe, sometimes fatal, amoebic meningoencephalitis.
  • True parasitism (obligate)- a parasitic life form is mandatory for at least one of the developmental stages. The true parasites are trypanosomes, leishmania, malarial plasmodia, porcine and bovine tapeworms, roundworms and many other species of living organisms.

According to the location of the parasite in (on) the host organism:

  • ectoparasitesthey live on the surface of the host's body, feeding on its blood (hematophages) or on the stratum corneum and its derivatives (keratophages). Human ectoparasites are usually insects and mites. Ectoparasites are often, at the same time, specific carriers of human pathogens.
  • Parasites that live in the cells, tissues, and cavities of the host body are called parasites.endoparasites. Accordingly, localization distinguishes intracellular, tissue, and cavity parasites. Endoparasites can affect any organ. There are intestinal parasites (ribbon and round worms, protozoa), parasites of the liver (flukes), parasites of the lungs (pulmonary flukes), genitourinary system (schistosomes, Trichomonas) and other organs. The parasite may be localized to a single organ or may infect multiple organs of the host.

According to the contact time of the parasitic species with the host:

  • temporary parasitesThey usually parasitize on the external integument of the host (ectoparasites). They are connected to the host organism only by food chains (for example, hematophages), and the contact time with the host is much shorter than the free-living period.
  • stationary parasitesspend on (on) the owner for a long time, sometimes all his life. For stationary parasites, the host organism is not only a food source, but also a habitat. Stationary parasites include almost all endoparasites and some ectoparasites. Stationary parasitism includes two forms of parasitism:Newspaper(the parasite spends part of its life in the external environment) andconstant(the parasite does not leave its hosts). Periodic parasitism is more common in nature than permanent parasitism.

By specificityParasites are divided into monospecific and polyspecific.

  • Parasites adapted to life in organisms of different biological host species are called parasites.polyspecific. A variant of polyspecificity is polyphagy, the ability of blood-sucking parasites to feed on the blood of hosts of different species. For example, the stages of sexual maturity of liver fluke (Fasciola hepatica) parasitize various herbivores; many types of mosquitoes (familiesCulicidae) feed on the blood of hosts belonging to several species of mammals.
  • If a parasite is adapted to live on a certain type of host, it ismonospecific. A variant of monospecificity is monophagy: the feeding of blood-sucking parasites at the expense of hosts of the same species. An example of monospecificity is the parasitization of human lice of the specieshuman pedicle. Once on the surface of the body of any other species, these lice die. human Ascaris (roundworm) are also monospecific parasites. Once in the body of other hosts, they die before reaching puberty.

What parasites live in the human body?

The internal flora of people is an excellent environment for the habitat and active reproduction of microorganisms belonging to the group of pathogens. The types of parasites in the human body are generally divided into two options: those whose presence is not felt and has little effect on general health, and those whose presence can be harmful. In the course of their life, they can not only negatively affect the organs, but also release toxic substances that poison all living things.

Most of the parasites in the human body are worms from the nematode group, which are diagnosed in both adults and children. Parasites can differ from one another in their location (in the intestines, liver, heart, and even the brain), size, life cycle, and even how long they are inside the body.

The most common types of parasites that affect people - nematodes are the following.

This microorganism parasitizes on the walls of the large intestine, while spreading the eggs of its future offspring outside the large or small intestine, for example, on bedding. Most often, this parasite is diagnosed in children. The worms cause itchy anus, decreased appetite, grinding of teeth while sleeping, and fatigue.

The life cycle of microorganisms is approximately one month and they reach a size of 12 mm. Pinworms are very resistant to the external environment, the appearance of new species occurs as early as 6 hours after egg laying.

These helminths live in the body of dogs and cats and enter the internal environment of humans through contact with these animals. This type of intestinal parasites can reach 3 cm in length and can be found in all internal organs and vessels without the need to go outside.

They belong to the type of the most dangerous infectious parasites in humans. They grow up to 3 cm in length and can live a long cycle. They penetrate all organs of the system, actively multiplying at the same time.


The parasitic invasion caused by trichinella can have negative consequences: edema, fever, dermatitis, indigestion and all kinds of allergies, including food allergies. The main difficulty in detecting these helminths lies in their microscopic size, which does not usually exceed 4 mm. The worm living in the intestines is able to penetrate the blood vessels, through which it spreads throughout the body through the bloodstream and settles in any organ.

Flukes also live quite frequently in the human gastrointestinal tract. They are distinguished by a flat shape and the presence of suckers. These additional organs are necessary for them to attach to human organs in order to suck useful substances from them.

The classification of parasites according to the type of helminths includes a class of trematodes, which consists of the following microorganisms:

  • Opisthorchis is a simple parasitic worm that often lives in the stomach, gallbladder, pancreas, and liver, leading to the development of gastritis, ulcers, and pancreatitis. The intestine in any form as such interests him little;
  • strongyloid - intestinal acne, is a worm up to 2 cm long that affects the gastrointestinal tract. Its lifespan is not long, but at the same time, its activity manages to lead a person to asthma, gastrointestinal dysfunction, bronchitis, asthenia and other diseases.

Since trematodes have access to any human organs and tissues, their invasion is considered the most common and the most difficult to treat.

These microorganisms devour a large amount of tissue and blood, often disabling the circulatory system.

Among all the existing parasites that live in humans, the most dangerous are cestodes. The length of this helminth can reach 10 M. Thinking about what kind of parasites live in the human body, it is difficult to imagine such a large worm that it would fit into the human body. They are introduced mainly in the case of eating contaminated meat.

The most common types of cestodes are:

  • pork tapeworm - grows up to 8 m in length Initially, symptoms of invasion do not appear, but then pork tapeworm activity leads to intestinal obstruction. It is also possible to develop asthenia;
  • bovine tapeworm - can grow up to 18 m in length Causes dangerous diseases for humans, such as anemia, intestinal obstruction, allergies, gastrointestinal disorders and, consequently, of the nervous system;
  • wide tapeworm - the length of this parasite reaches 8 m. One of the few parasites in humans that lives in the small intestine. It causes anemia, asthenia, problems with the digestive tract and intestinal obstruction;
  • echinococcus - is considered the most dangerous tapeworm, the infection of which in the early stages does not show any symptoms. However, too rapid spread of the helminth throughout the body leads to the formation of tumors.


Thinking about what kind of parasites are in the human body, do not forget about the possibility of infection with the so-called protozoa. This class of microorganisms has nothing to do with the three groups of helminths, since it constitutes its own special parasitic species that inhabits various human organs.

Protozoa belong to the class of endoparasites that can be located in almost any corner of the body. This species got its name from a simple structure consisting of a single cell. However, they can cause various dangerous diseases in the human body.

The main types of parasitic protozoa:

  • Trichomonas. Despite the presence of a single cell, they have a very complex structure. There are several types of parasites of this type, depending on the degree of localization: oral, intestinal and vaginal. The most common infections occur in the presence of this organism in the reproductive system. Trichomonas often lead to prostatitis in men. Affects the brain and nervous system;
  • lamblia. Located in the intestine. They lead to dysbacteriosis, gastrointestinal discomfort and general intoxication of the body. They usually adhere to the mucous membrane of the duodenum, where they actively multiply;
  • amoeba. Capable of causing asthenia and indigestion, and also creating intestinal obstruction;
  • toxoplasma. This parasite is very dangerous for a pregnant woman, as it can lead to miscarriage in the early stages. In addition, Toxoplasma causes diseases of the eyes, the nervous system and the heart.

A particular danger of infection of the human body with unicellular protozoan microorganisms is that in most cases the developing infection is asymptomatic.


This type of parasitic microorganisms, such as ectoparasites, constitute a separate group of dangerous carriers of infection. This class is distinguished by the fact that its representatives are located exclusively on the surface of the human skin, but, nevertheless, they can infect it with such dangerous diseases as anthrax, typhoid, encephalitis, trypanosomiasis and others.

It is not difficult to recognize the appearance of parasites of this group, since, as a rule, they cause significant discomfort to their host. The main consequences of their bites include the appearance of allergic reactions, itching and burning.

Coping with such microorganisms is possible only with the help of special means. In addition, as a general rule, sanitation of the premises, bedding and clothing is required. Very dangerous ectoparasites of an exotic species, which can be picked up during travel. Bites from some of them can be fatal.

Read more: Is it possible to treat the throat of a nursing mother with the help of Lugol? Will it hurt the chest?

The fight against parasites in the human body, regardless of their location, must be carried out comprehensively and in consultation with the doctor. However, the important point is the correct diagnosis of infection with dangerous microorganisms.

Usually, the symptoms that the human body has been susceptible to parasitic infection are as follows:

  • constipation - due to intestinal obstruction associated with large worms. Also, helminths can block bile flows, causing painful discomfort in the lower abdomen;
  • frequent gas formation, usually caused by worms that have settled inside the small intestine. This also includes the so-called irritable bowel syndrome;
  • diarrhea - liquefaction of feces is caused by special substances secreted by some of the microorganisms. Loose stools that are too frequent may indicate an infection;
  • allergic reactions - usually occur in the waste products of microorganisms inside a person. It is also possible the appearance of eczema and rashes on the skin;
  • painful discomfort in the joints and muscles. If this sign appears for no apparent reason, it is mandatory to check for the presence of parasites. Some of them prefer to live exclusively in joint fluids and muscles, and pain is an immune response to the appearance of microorganisms;
  • weight jumps, problems with appetite - they are associated with human poisoning by the waste products of parasites and a lack of glucose;
  • chronic fatigue syndrome, sleep disturbance, anxiety and irritability. He says more often that the body's resources are depleted due to the vigorous activity of the parasites within it.

There are many types of parasites that can live in the human body. Most infections in the early stages are completely asymptomatic. However, the treatment of parasitic invasion in the early stages is considered the most effective and simplest.

What are the types of parasites that live in the human body?

Creatures that live in the body of animals, humans, birds, and fish and feed on their host are called parasites.The vital activity of such organisms in the human body does not lead to anything good, parasites can cause serious complications and even death. Consider the types of parasites in the human body in more detail. Below is a detailed classification of parasites.


  • The simplest - these include giardia, dysenteric amoeba, trypanosome, etc.
  • Pinworms: pinworms and roundworms take root well in the human body
  • Flatworms: the human body is an excellent place where porcine and bovine tapeworms, liver flukes, etc. can live.
  • lice and fleas
  • ticks and horseflies

It is quite difficult to deal with these types of parasites, because in the course of their life they settle and reliably stick to the walls of the organs with the help of suction cups and special hooks.

Some individuals can usually live in cells and tissues, and from there it is almost impossible to remove them. It's about worms. With insects the situation is a bit simpler, since they are usually located on the surface of the body, where they can be detected and destroyed in time.

What parasites live in the intestines? So, let's analyze each of its varieties and places where parasitic worms and protozoa live.


This type of parasite in the human body is also very dangerous. These worms are called flatworms because their body shape resembles flat ribbons. There is also the most harmless type of flatworms for humans - these are ciliary worms. But let's talk about dangerous parasites, trematodes and tapeworms, in more detail.

The flatworms of this species are small in size, but they adhere very firmly to the walls of human organs thanks to their suckers. The fluke, which parasitizes mainly in the liver and intestines, causes anemia, constant headaches and sudden weight loss. This helminth can, in the course of its life, penetrate the lungs, and even the brain, causing serious consequences. The source of flukes is dirty water and plants.

This type of worm is very long and constantly grows to its full potential. A tapeworm can grow up to 6. 5 meters in its entire life. Representatives of tapeworms - bovine and porcine tapeworm - can reach a length of up to 10 meters. Parasites live in the human intestine, that is, in the small intestine. The most dangerous type of tapeworm is Echinococcus, which can affect the brain and lungs.

Losing weight with a normal appetite is the main sign of a tapeworm infection.

round worms

These types occur mainly in children: kindergarten children and elementary school students. The most popular are roundworms, these are pinworms and roundworms, which tend to parasitize in the intestines.

These types of parasitic worms do not attach to the walls of human organs in any way, as roundworms do not have any adaptations for this, however, they are not easy to remove. Pinworms tend to lay their eggs in the folds of the anus, causing excruciating itching in the perianal area. Children become infected "in a circle": scratching the itchy place, pinworm larvae remain on the hands and under the nails, and when the child accidentally puts his fingers in his mouth, the infection recurs.

And if the symptoms appear occasionally, then people in the modern rhythm of life simply do not notice them or do not give them much importance. And very in vain. There are many terrible and irreparable consequences.

Experts recommend that at least once a year tests for parasites be carried out: feces, blood. After all, it is the timely detection of parasites in humans and competent treatment that will ensure a higher quality of life.

What happens to a person in whose body parasites live for a long time?

  • The forces are exhausted as the parasites multiply and grow.
  • Immunity is greatly reduced, as the body puts all its strength into pest control.
  • Any, even the simplest virus or infection can infect a person, since the body cannot protect itself from viruses.
  • Throughout their lives, parasitic individuals secrete toxins that gradually accumulate in the human body. It gradually poisons itself, which is fraught with various infectious and even malignant diseases.


Prevention is an essential part of pest control. It was said above what parasites are in the human body. As for worms and protozoa, modern medicine offers a huge selection of drugs for the prevention and control of pests.

But you should not prescribe the drug yourself, you should first consult a specialist, especially if you are worried about any symptoms. After conducting the necessary tests, the doctor himself will prescribe the correct drug, based on the parasites that live in the human body.

After all, each drug acts on certain types of parasitism, unfortunately, there is no universal one yet. And it is a specialist who will help you choose a drug that is relevant in this case, fighting a certain type of parasite in a person.