Trypanosomes are dangerous parasites.

Trypanosomes are one of the families of protists - single-celled organisms of the type Euglenozoa.

Trypanosomes are pathogenic microorganisms and pose a health hazard, causing severe damage to human systems and organs.

Structure of trypanosome

The structure of the trypanosome, i.e. its morphological structure, has the form of a trypomastigote during the adult, trypanosomal stage of development. The body of the trypanosome, from 12 to 40-70 µm long, has a longitudinal shape of a strongly elongated oval with pointed ends (resembling a spindle).

It consists of one cell - a mitochondrion with cytoplasm and a single nucleus; the cell has a dense glycoprotein membrane (periplast). Also in the trypanosome cell there is a disc-shaped organelle kinetonucleus (or kinetoplast), containing DNA, and a smaller body (kinetosome or blepharoplast), from which the external outgrowth of the trypanosome cell flagellopodia begins. This organelle of parasite movement is simply called a flagellum. It stretches along the cell body and lifts the lamellar membrane formed by the periplast, which is also located along the entire cell (on one side). Specialists call it an undulating membrane (from Latin undulatus - wave-like), and its function is to wriggle and move the trypanosome in the desired direction. This structure of the trypanosome is inherent in the parasite when it is in the body of the final host.

In addition, while there, the trypanosome can also be in the form of an amastigote (oval, smaller in size and without a flagellum). But at the critical stage, while in the body of the insect carrier, the morphological structure of the cell takes the form of an epimastigote: the cell is elongated, but the flagellum is short and the wavy membrane is greatly underdeveloped.

By the way, Trypanosoma cruzi has a C- or S-shaped body, as well as a longer flagellum and a narrowed, wavy membrane.

Life cycle and reproduction of trypanosome

Trypanosomes are obligate parasites, meaning that their existence outside of another organism is impossible: the host provides food and a comfortable environment for the parasite. Therefore, the entire life cycle of a trypanosome takes place either in the body of an insect or in the body of a human (or animal). So the life cycle of this parasite is two-stage.

The main (definitive) host for trypanosomes, according to most biologists, is man, and the blood-sucking insect that carries the parasite has received the status of an intermediate host.

The African trypanosome develops in the anterior sections of the tsetse fly's intestine after it has sucked the blood of an infected vertebrate. As a result, its body is filled with trypomastigotes of Trypanosoma brucei or Trypanosoma gambiense, which begin to multiply and turn into epimastigotes. Having reached the insect's salivary glands, the epimastigotes continue to divide vigorously. The life cycle of the trypanosome in the fly's body takes about three weeks. The parasite penetrates directly into the saliva only when it develops to the stage of metacyclic trypomastigotes, which enter the proboscis. Now the bloodthirsty insect only has to bite the victim of its insatiable appetite, and that's it - mature trypanosomes migrate to a new host.

At first, trypomastigotes remain in skin cells for some time (up to ten days), from there they move into the lymphatic system, and then pass into the blood, sticking to erythrocytes and leukocytes. But they cannot reproduce in the blood and with the bloodstream they “travel” throughout the body in search of a suitable “place to live” - in the cerebrospinal fluid, lymph and in various organs. And there the reproduction of trypanosomes begins, which leads to poisoning of the body with metabolites of its vital activity and damage to the tissues of internal organs.

Trypanosome reproduction is asexual, carried out by longitudinal binary mitosis, during which the mitochondria and nucleus are divided into two parts - replicating two copies of each chromatid.

The repeated process of division of the American trypanosome (with the formation of an epimastigote) occurs in the intestines of bedbugs. When the parasite cell becomes a trypomastigote, that is, it acquires a metacyclic form, it is ready to change hosts. There is only one way out of the intestines - with excrement, which animals lick off themselves when bitten by an insect and become infected. And people scratch the bitten place, and the infectious feces of the bedbug get into the skin cells through the hole from the bite and microscopic damage to the integrity of the skin when scratching.

Where does trypanosome live and what does it eat?

So, where does trypanosome live? The parasites Trypanosoma brucei and Trypanosoma gambiense have chosen blood, lymph, lymph nodes, cerebrospinal fluid (cerebrospinal fluid), protein-rich serous fluids, as well as tissues of the spinal cord and brain as their habitat. American trypanosome in the human body most often settles in the cells of the lymph nodes and vessels, liver and spleen, bone and brain, as well as muscle tissue (including the myocardium).

What do trypanosomes eat? What they need to maintain their existence and reproduction - glycoproteins and carbohydrates of the blood plasma of their host. Trypanosomatids do not have openings for food to enter (cytostome), so they satisfy their hunger with the help of endosmosis - the absorption of liquid nutrients by the entire cell membrane. It should be noted that trypanosomes are anaerobes, that is, they do not need oxygen to obtain energy and their respiratory system is cytochrome.

The mechanism of adaptation of trypanosomes to the host organism and the method of protection against it are recognized by microbiologists as unique. In order to "mislead" the immune system of a human or animal, the trypanosome gene is activated, which is engaged in changing the sequence (recoding of peptide bonds) of amino acids that are part of their protein shell. That is, foreign agents (antigens) of the parasite, to which the immune cells of the host organism react, change, and the process of their detection, identification and neutralization is delayed. And during this time, trypanosomes have time to multiply.

Types of Trypanosomes

According to parasitological classification, the class of trypanosomes are heterotrophic eukaryotic pathogenic endoparasites.

Trypanosoma in Latin (borrowed from Greek): class Mastigophora (flagellates, from Greek mastig - flagellum), subclass of animals flagellates (Zoomastigina), order Kinetoplastida (kinetoplastids). And according to the classification of protists, the class of trypanosomes is kinetoplastida, family - trypanosomatids, species - trypanoplasma. Several varieties of this endoparasite cause very dangerous pathologies in humans.

African trypanosoma is the cause of African trypanosomiasis (sleeping sickness) in humans and animals. The disease occurs after the body is infected with parasites such as Trypanosoma brucei and Trypanosoma gambiense. In the first case, doctors define the pathogen as Trypanosoma brucei gambiense (Tbg), which affects the population in the countries of West and Central Africa and causes a chronic infection that lasts for months and years. In the second case, the type of pathogen has a more precise name Trypanosoma brucei rhodesiense (Tbr), and it leads to an acute form of sleeping sickness (with severe damage to the central nervous system) mainly among the rural population of the eastern and southern parts of the African continent.

The method of infection with trypanosomes of these species is inoculative - through the bite of a specific blood-sucking insect. The tropical tsetse fly, which lives in countless numbers, is a carrier of trypanosomes brucei and gambiense. The main species of tsetse fly (Glossina) that can infect people with African trypanosomiasis include G. palpalis, G. tachinoides and G. morsitans.

Trypanosoma cruzi or American trypanosoma is endemic to Central and South America. Its invasion of the body results in Chagas disease (named after the Brazilian bacteriologist Carlos Chagas who discovered it), accompanied by inflammation of the heart muscle and the membranes of the brain. The method of infection with trypanosomes cruzi is inoculative-contaminative: - the bite of one of the species of triatomine hematophagous bugs (Triatoma infestans, Rhodnius prolixus, etc.), as well as the entry of infected feces into the scratched bite of the bug. The bug itself becomes infected by biting walking and flying "depositors" of the parasite - rodents, armadillos, opossums, bats, etc.

Trypanosoma eouipedum causes the so-called mating disease of horses, since the transmission of trypanosomes of this species occurs during their mating. Trypanosoma brucei is often referred to as equine trypanosome, since horses in central Africa are infected with it, and the developing fatal disease nagana (ngana) affects many other domestic animals.

Prevention of trypanosomes

The main prevention of trypanosomes today is the fight against their carriers - insects. For this, all available means of protection are used: repellents, mosquito nets, screens and traps to prevent tsetse flies and bedbugs from entering residential and public premises, treating the habitats of these insects with insecticides to destroy them. And, of course, monitoring the health of the population in endemic areas - by regularly taking blood tests for Trypanosoma brucei gambiense (Tbg).

Human trypanosomiasis is endemic in 36 countries in sub-Saharan Africa, home to nearly 70 million people. According to the WHO, which has adopted and is implementing a program to combat sleeping sickness in African countries, an average of 25,000 people fall ill each year. Moreover, since this is a rural disease, many patients are diagnosed but not treated and die in their villages…

It is currently recognized that the most effective prevention of trypanosomes is clearing certain areas (especially in areas of high humidity) of those types of vegetation that serve as a refuge for flies.

The importance of trypanosomes in nature

If protists, which include trypanosomes, are an integral part of the biosystem of our planet, and many of them make a positive contribution to its stabilization (producing oxygen, absorbing bacteria and processing organic remains), then the significance of trypanosomes in nature - like, for example, the malarial plasmodium, dysenteric amoeba or lamblia - is difficult to determine.

Scientists consider parasitism as a principle of existence of some organisms at the expense of others. If such existence harms one of its participants, causing dangerous diseases of the parasite's host - a person, then the thought involuntarily comes to mind that 7 billion people of the Earth are nothing compared to the number of parasitic microorganisms living on the planet.

We consider them a class of protozoa, but they, having mitochondria and flagellum, have adapted to such extreme conditions in which no human could survive for even a few minutes.

Of course, an article about trypanosomes is clearly not a reason for philosophizing, but perhaps the significance of trypanosomes in nature is that man nevertheless recognizes himself as a part of this nature and begins to behave not as its conqueror or, even worse, its king...