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.

zoologicalthe classification establishes the parasite's belonging to certain systematic categories: type, class, order, family, gender.

Environmentalthe classifications are based on the lifestyle characteristics of the parasite.

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

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

ectoparasites-parasitizing on 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) - roundworms, pulmonary fluke;
  • in tissues (musculoskeletal system, subcutaneous fat) - Guinea worm, trichinella;
  • intracellular (malarial plasmodium);

transitional forms.For example, in the stratum corneum of the epidermis, the parasitic itchy 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 development cycle takes place in the body of an owner (trichomonas, scabies, lice);
  • temporary parasites- only part of the development cycle takes place in the host organism (bloodsucking 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

Hosts are divided intofinal, intermediateAndreservoir.

Final (basic, definitive)- hosts in whose organism the parasite is sexually mature or reproduces sexually (malarial mosquito for malarial plasmodium, man for sexually mature swine tapeworm).

Intermediate- hosts in whose body the parasite is in the larval stage or reproduces asexually (humans for 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. 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 large tapeworm can parasitize. Man is for him the supreme teacher. There are two intermediate hosts in the development cycle: the first is the Cyclops crustacean, the second is many species of fish. But non-predatory fish can be eaten by predators, for example, pike. In this case, the helminth larvae do not die, but accumulate in the muscles of the pike and become a reservoir host.

So,the host organism is a kind of habitat for the parasite.The doctrine of the host organism as a habitat of the parasite was most fully developed by academician E. N. Pavlovsky.The totality of all organisms living in any organism at the same time is called parasitocenosis.

Classification of parasites

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

  • false parasitism- single individuals of a free-living species accidentally enter the body of another species, where they remain viable and cause disturbances to 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, the coprophilic amoeba can live in feces. When the feces dry out, they encyst. Coprophilic amoeba cysts can accidentally enter the human intestine. Usually the cysts pass through the intestine and are excreted in the external environment with the feces. In some cases, amoebas in the human intestine emerge from the cysts and become parasitic for a short period of time, causing acute digestive upset.
  • facultative parasitismsuggests the possibility for a species to lead both a free and parasitic lifestyle. 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 generaNaegleriaAndAcanthamoeba. Negleria and Acanthamoeba live in water bodies that receive wastewater. Entering the human body through the mouth or wounds on the skin, they can cause severe, sometimes fatal, amoebic meningoencephalitis.
  • True (obligatory) parasitism- a parasitic lifestyle is mandatory for at least one of the development stages. True parasites are trypanosomes, leishmania, malarial plasmodia, swine 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 both its blood (hematophagus) and 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 calledendoparasites. Consequently, localization distinguishes intracellular, tissue and cavity parasites. Endoparasites can affect any organ. There are intestinal parasites (ribbons and roundworms, protozoa), parasites of the liver (flukes), parasites of the lungs (lung flukes), genitourinary system (schistosomes, Trichomonas) and other organs. The parasite can be located in a single organ or infect various host organs.

Based on the contact time of the parasite species with the host:

  • Temporary parasitesThey usually parasitize the host's external integument (ectoparasites). They are connected to the host organism only by food chains (for example, bloodsucking) and the time of their contact with the host is much shorter than the free life period.
  • Stationary parasitesthey spend a long time in (on) the owner, sometimes for a lifetime. 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:periodic(the parasite spends part of its life in the external environment) econstant(the parasite does not leave its hosts). Periodic parasitism is more common in nature than permanent parasitism.

By specificityparasites are divided into monospecific and polispecific.

  • They are called parasites adapted to life in organisms of different biological species of hostspolispecific. A variant of polispecificity is polyphagia, the ability of blood-sucking parasites to feed on the blood of hosts of different species. For example, the sexually mature stages of liver fluke (Liver fluke) parasitize various herbivores; many types of mosquitoes (familiesCulicides) feed on the blood of hosts belonging to different mammal species.
  • If a parasite is adapted to life in a certain type of host, it ismonospecific. A variant of monospecificity is monophagy: feeding 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 pedicule. Once on the surface of the body of any other species, these lice die. Human ascaris (Ascaris lombricoides) are also monospecific parasites. Once in the bodies 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 habitat and active reproduction of microorganisms that belong to the pathogenic group. 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 are able not only to negatively affect organs, but also to release toxic substances that poison all living things.

Most parasites in the human body are worms from the nematode group, diagnosed in both adults and children. Parasites can differ from each other in their location (in the gut, liver, heart and even brain), size, life cycle, and even the time they are inside the body.

The most common types of parasites that affect people - roundworms are as follows.

This microorganism parasitizes in 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. Worms cause itching in the anus, decreased appetite, grinding of teeth in sleep, and fatigue.

The life cycle of microorganisms is about 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 spawning.

These helminths live in the body of dogs and cats and enter the internal environment of man 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 going out.

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


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

The flukes also live quite often in the human gastrointestinal tract. They are distinguished by a flat shape and by the presence of suction cups. These additional organs are necessary for them to attach themselves to human organs in order to draw useful substances from them.

The classification of parasites according to the type of helminths includes a class of flukes, consisting of the following microorganisms:

  • Opisthorchis is a simple parasitic worm that often lives in the stomach, gallbladder, pancreas and liver, which leads to the development of gastritis, ulcers and pancreatitis. The intestine in any form as such is of little interest to him;
  • strongyloid - intestinal acne, is a worm up to 2 cm long that affects the gastrointestinal tract. Its life 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 flukes have access to any human organ and tissue, invasion by them is considered the most common and difficult to treat.

These microorganisms devour huge amounts of tissue and blood, often disabling the circulatory system.

Of all the existing parasites living in humans, the most dangerous are tapeworms. 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 huge worm that fits into the human body. They mainly come in the case of eating contaminated meat.

The most common types of tapeworms are:

  • pork tapeworm - grows up to 8 m in length Initially, the symptoms of invasion do not appear, but later the activity of the pork tapeworm leads to intestinal obstruction. It is also possible to develop asthenia;
  • bovine tapeworm - can grow up to 18 m in length Causes dangerous disorders for humans, including anemia, intestinal obstruction, allergies, gastrointestinal disorders and, consequently, the nervous system;
  • wide tapeworm - the length of this parasite reaches 8 m One of the few parasites in humans living in the small intestine. It causes anemia, asthenia, problems with the digestive system 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 a spread of the helminth throughout the body leads to the formation of tumors.


Thinking about what kind of parasites there 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, as it constitutes a special parasitic species that lives in various human organs.

Protozoa belong to the class of endoparasites which 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 only one 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 that occur in the presence of this organism in the reproductive system. Trichomonas often leads to prostatitis in men. They affect the brain and nervous system;
  • lamblia. Localized in the intestine. They lead to dysbacteriosis, gastrointestinal disorders and general intoxication of the body. Usually attached to the mucous membrane of the duodenum, where they actively multiply;
  • amoeba. Able to cause asthenia and indigestion and also create intestinal obstruction;
  • toxoplasma. This parasite is very dangerous for a pregnant woman, because it can provoke a 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 protozoan unicellular 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 vectors of infection. This class is distinguished by the fact that its representatives are localized exclusively on the surface of human skin, but, nevertheless, they are able to infect it with such dangerous diseases as anthrax, typhus, encephalitis, trypanosomiasis and others.

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

To cope with such microorganisms is possible only with the help of special means. Furthermore, as a rule, the sanitation of the premises, bed linen and clothing is required. Very dangerous ectoparasites of an exotic species, which can be collected during the trip. The bites of some of them can be fatal.

Read More: Is It Possible to Heal a Nursing Mother's Throat With Lugol's Help? Will she hurt the chest?

The fight against parasites in the human body, regardless of their location, should be conducted 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. In addition, helminths are able to block biliary 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 - the liquefaction of stool is caused by special substances secreted by some microorganisms. Too frequent loose stools may indicate an infection;
  • allergic reactions - usually occur on the waste products of microorganisms inside a person. The appearance of eczema and skin rashes is also possible;
  • pain pain in the joints and muscles. If this sign appears for no apparent reason, it is mandatory to check for 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, appetite problems - are associated with human poisoning by waste products of parasites and a lack of glucose;
  • chronic fatigue syndrome, sleep disturbances, anxiety and irritability. He more often says that the body's resources are depleted due to the vigorous activity of 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 simple.

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

Creatures that live in the bodies 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.
  • Roundworms - roundworms and pinworms take root well in the human body
  • Flat worms - the human body is an excellent place where pork and bovine tapeworms, liver flukes, etc. can live.
  • Lice and fleas
  • Ticks and horseflies

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

Some individuals can generally live in cells and tissues and it is nearly impossible to get them out of there. These are worms. With insects, the situation is somewhat simpler, as they are usually found on the surface of the body, where they can be detected and destroyed over time.

What parasites live in the intestine? Next, let's break down each of their varieties and places where parasitic worms and protozoa live.

Flat worms

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

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

This type of worm has a very large length and constantly grows to its full potential. A tapeworm can grow up to 6. 5 meters throughout its life. Representatives of tapeworms - bovine and porcine tapeworms - can reach a length of up to 10 meters. Parasites live in the human intestine, especially the lean. 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.


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

These types of parasitic worms do not attach themselves to the walls of human organs in any way, as nematodes have no adaptation for this, however they are not easy to remove. Pinworms tend to lay eggs in the folds of the anus, thus causing unbearable itching of the perianal area. Babies become infected "in a circle" - by scratching the itchy spot, the pinworm larvae remain on the hands and under the nails, and when the baby accidentally puts his fingers in his mouth, the infection returns.

And if symptoms appear occasionally, people in the modern rhythm of life simply don't notice them or attach much importance to them. And very in vain. There are many terrible and irreparable consequences.

Experts recommend at least once a year to be tested for parasites: feces, blood. After all, it is the timely detection of parasites in humans and competent treatment that will ensure the further 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 pours all its strength into parasite control.
  • Any virus or infection, even the simplest one, can infect a person, as the body is unable to protect itself from viruses.
  • Over the course of their life, parasitic individuals secrete toxins which gradually accumulate in the human body. It is gradually poisoned, which is fraught with various infectious and even malignant diseases.


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

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

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