Medical parasitology: definition, diseases, classification of parasites

Our world is beautiful and fantastically diverse. Thousands of life forms admire their beauty, strength, ability to survive and other unique features. But, unfortunately, there are beings in the world who are absolutely unattractive and differ only in that they live at the expense of other beings. These are parasites. Medical parasitology deals with those of them that are dangerous to human health and life.

It's hard to imagine how many of them exist on Earth. These are viruses, bacteria, fungi, helminths, insects, and protozoans - only a few million species, and most of them are more or less capable of harm. In order to determine exactly which type of parasite has settled in a person and causes him trouble, there are special medical and research institutions, for example, in Moscow it is the Institute of Parasitology, and also of tropical medicine named after Marcinovsky. Here, studies are conducted to identify pests and prescribe effective treatment.

Similar institutions exist in many large cities of all developed countries of the world, because parasites attack people of all ages, races, nationalities and sexes, and at any time of the year. How to recognize that you were the victim of a small pest and killer? What to do and where to run for help? Let's understand.

What is parasitology?

To get started, let's read some of the terms. The most common of these is parasitology. This is a whole science that deals with the study of all biological parasites, their morphological features, vital activity, principles of parasitism, etiology, pathogenesis, as well as the development of methods to combat them and the discovery of new drugs to treat the diseases they cause. One of the major areas of this science, specializing in human pests, is medical parasitology. Definition of it can be given the following: it is a section in medicine that studies all forms of manifestation of pathogenic activity of pests - how they infect a person, what it causes diseases, how they flow, how dangerous, how to treat them and how to protect them.

There is also a veterinary parasitology, which, in principle, is the same as the medical one, only for animals. In nature there is a group of organisms capable of hitting both humans and animals. But in most cases, microorganisms by evolution have adapted for parasitic activity in any one host species, for example, only in birds, either only in humans, or only in warm-blooded animals. Therefore, there are two sections of parasitology, one of which deals with microorganisms that cause human diseases, the other - animals.

Sections of medical parasitology

The army of parasites is not only numerous, but also multifaceted. Each of their species has its own peculiar features of vital activity and causes completely different pathologies. To facilitate the task of scientists and somehow differentiate the research that they are engaged in, medical parasitology has identified several sections that are only interested in certain types of living forms:

- protozoology;

- arachnoentomology;

- Helminthology.

Important: the symptoms of invasion caused by representatives of any of these sections are very often similar to the symptoms of diseases not associated with parasite infestation, so medications that do not lead to a positive result can be prescribed without appropriate analyzes. To exclude the possibility of invasion, you need to contact the medical center of parasitology (if it is available in the village) or to another medical institution engaged in the diagnosis of parasitic diseases.

Medical protozoology

The complex word "protozoology" is made up of three simple ones, which in Greek mean the following: "proto" - the first, "zoo" - animal and "logic" - in free translation it is a question of something, teaching. That is, the section of medical parasitology of protozoology deals with the study of parasitic life forms, which arose one of the first on the Earth. All of them are single-celled protozoa - amoeba, known from the school infusoria bench and others. Most of them live in the environment without causing us trouble, but some members of the group have adapted to life in other organisms. Once in a person, they cause parasitic or, in other words, invasive diseases. Such dangerous microorganisms include:

1. Amoeba. Their size is 0.5 mm and smaller, and the body constantly changes shape, protruding some processes and drawing others. These tiny creatures, hitting the human intestines, cause a formidable disease of amoebiasis, occupying the "honorable" second place in the world in mortality from invasive pathologies. In humans, several species of amoeba are parasitized. Dysenteric (Entamoeba histolytica) is the culprit of dysentery, the simplest kind of Acanthamoeba provokes amoebic keratitis, and a number of amoebas cause amoebic encephalitis. You can get infected by drinking water or products containing amoebic cysts, as well as in close contact with their carrier. Having got into the intestine and penetrated into its walls, amoebae with blood are carried along the body of a person, settle in other organs of the body, more often in the liver and form additional foci of amoebiasis.

2. Flagellates. As the name implies, these protozoa are moved with the help of cilia, flagella and other similar formations. Medical parasitology and parasitic diseases are closely related, whatever kind of organisms are considered. In particular, flagellar vaginal trichomonads cause urogenital trichomoniasis, fraught with infertility, and in cases when pregnant women get it, trichomoniasis can cause a miscarriage. Trichomonads, unlike many other parasites, live only in man and are transmitted by close contact (sex). Other vivid representatives of the flagellates are members of the genus Leishmania, a gambian trypanosome that causes deadly African trypanosomiasis. Trypanosomes carry tsetse flies. Once in a person, parasites move to the brain. Their activity disrupts the work of almost all body systems. Still there are sporoviks, the most dangerous of which is Taxoplasma gandi, which causes toxoplasmosis.

3. Infuzoria. Among them there are not only shoes, but also Balantidium coli, getting into the intestine leads to a serious illness balantidiasis. Infecting the intestinal balantium is possible from domestic animals, eating their unprocessed culinary processing of meat, as well as consuming water and products with cysts of parasites.

Medical arachnoentomology

In Greek, "arachnis" is a spider. Accordingly, arachnoentomology is a medical parasitology that deals with arachnid and generally arthropodic insects parasitizing on a human being. In total, more than one and a half million such parasites have been discovered. They can be temporary (attacked, drank blood and left victim) and permanent (live on the victim from birth to death). This group of parasites poses a great danger for the reason that they suffer severe and often even fatal invasive diseases. So, mites reward us with encephalitis, recurrent typhoid, borreliosis, scabies, fleas bring us plague, typhus, bugs - Chagas disease, mosquitoes - malaria, anthrax, yellow fever. There are other dangerous insects parasites - midges, a tsetse fly, horseflies, woodworm. In addition, there is a huge detachment of insects, in essence parasites that are not, but also carry dangerous diseases. These are flies, cockroaches, various beetles.

Medical helminthology

Among the parasites of man there are not only microscopic, but also large enough, perfectly visible to the naked eye, and sometimes even huge individuals. These are worms and worms, and scientifically helminths. Every year every second inhabitant of our planet becomes infected by them, and in Russia, according to research, 99% of the inhabitants suffer from helminthiasis. Therefore, it is difficult to overestimate the importance of the work, which is engaged in medical parasitology, saving our citizens from this infection. Helminthes can be picked up not only by those who do not observe hand hygiene or eat unwashed fruit-vegetables, but also those who eat unprepared dishes from the meat of domestic animals, poultry, fish, and drink unpeeled water.

You can get infected even accidentally, for example, by ingesting a carrier ant-helminthic larvae or cysts with food. There is a group of worms (they are called contact) that enter the body of the victim through undamaged skin. Medical parasitology, in particular helminthology, deals not only with the differentiation of worm species, but also with the study of the cycles of their development, since for one group the person is the final host, and for the other, intermediate.

It is also important to study how and at what stage of its development a parasite can penetrate a person, which animal becomes an intermediate host, and how the life activity of a person is connected with this. This is especially true for flatworms. For example, for bovine tapeworm, which grows up to 10 meters in a person's body, it is cattle, for a pig's chain-pig, for a wide ribbon-fish.

Nematodes

So called roundworms, which are found in nature and described 24 thousand species. Fortunately, not all of them parasitize in humans, but those who have chosen people for themselves in the course of evolution cause rather unpleasant diseases - nematodes. The most well-known round worms are pinworms, which are the most common helminths in children all over the world and cause enterobiasis. Only in a man (in the intestine) live pinworms, infection occurs through dirty hands, unwashed fruits, vegetables, linens and household items that the patient uses.

The parasitologist easily identifies the invasion with pinworms according to the only characteristic symptom - a strong itch in the anus, as helminths there lay eggs. To cause itching, they secrete a special acid. The patient begins to comb these places, and eggs in this process fall into their hands, and then into the mouth, clothes, toys - anywhere. In the external environment, they live long, so the next victim, if she does not wash her hands, can easily plant pinworm in her body. Another known representative of nematodes are ascarids, which cause ascariasis. They also live only in man, but at different stages of their development settle in the lungs or in the intestine. The source of infection in this case is also only a sick person, and the cause of infection lies in insufficient personal hygiene.

Diagnostics

As can be seen from all of the above, there are hundreds of human parasites, and each has its own peculiarities. To establish an accurate diagnosis, the physician parasitologist necessarily collects an anamnesis:

- find out the conditions under which infection could occur (the patient's life, work or leisure time, for example, in the forest or in countries where epidemics of parasitic diseases are frequent);

- the presence or absence of contact with animals of various groups in the patient, and so on);

- Symptoms of the disease (there is an itch, a rash, signs of intoxication, weakness, anemia).

A decisive role in the diagnosis is performed by laboratory studies. They are direct and indirect. Direct are the detection of eggs, larvae or other living forms of parasites in human secretions (feces, sputum, urine). This work is carried out by the laboratory of parasitology, where the patient must pass only fresh materials for research. So, some types of helminths can be found in the stool no later than 20 minutes after defecation.

If it is difficult or impossible to collect fresh material (for example, if the parasites are in the liver, in the brain), indirect tests are performed. They consist in the detection in the patient's blood of special antibodies produced by the body to protect against invasion.

Treatment

Parasitology medical products to destroy the human body parasites offers a wide variety. One means that saves from all forms and types of infestation does not exist. Therefore, only doctors should prescribe the treatment, and only after an accurate diagnosis. To date, preparations have been developed that include mebendazole, diethylcarbamazine, levamisole, piperazine adipate and other substances. Each of them can destroy only a certain type of parasites. In some cases, for example, when infected with bovine chain, the treatment is performed surgically.

Veterinary parasitology

This section is important not only for people who have pets, but for each of us, since even those who have absolutely no contact with animals in any way can get infected by eating meat, fish, or they may become a victim of insect bites. Veterinary parasitology solves a very wide range of tasks:

- examines pets for the presence of all known to date parasites;

- makes treatment;

- makes sure that contaminated meat is not caught on the shelves of shops, other animal products, as well as fish and seafood, examine live and fallen animals, and, in case of detection of infestation, establish quarantine zones en masse.

Prevention

In order not to suffer from many kinds of parasites, excellent vaccines have been developed to date. Apply them necessarily, leaving for rest or work in Latin America, Africa, and other regions where there live specific insects (kiss bug, tsetse fly and others) that can cause dangerous diseases. For vaccination, it is necessary to apply to the institute of parasitology or to the medical institution of your locality, which is engaged in this activity. For residents of regions in which outbreaks of diseases caused by parasitic insects (for example, for tick-borne encephalitis are Ural, Siberia, the Far East) are frequent, and vaccination is also mandatory for those who are going to permanent or temporary residence in these regions.

An important point in the prevention of invasive diseases is the use of food only tested by the sanitary and epidemiological service products. In addition, do not use water from ponds without pre-boiling.

But the main, accessible to all layers of the population means to prevent invasion, is hygiene, that is, washing hands, fruits, vegetables, as well as a sufficient culinary processing of meat, fish, milk.