The simplest organisms that live in the Earth's water bodies, soil and air number up to 15, 000 species. Some of them are the oldest inhabitants of our planet. In the millions of years since the appearance of the first living organism, most protozoa have not changed much. But they have learned to adapt well to the new living conditions and to find ways to survive. One of the most obvious modes of existence of these organisms has become parasitism, including in the human body.
Parasitism
It is a kind of complex relationship between two creatures, when a parasite uses another organism as habitat or food resource.
The organism in which the parasite lives is called the host. It can be permanent when the parasite goes through the entire cycle of its development there and intermediate, when the pathogenic organism only passes a certain stage of its life cycle.
Parasitism among protozoa is a type of interaction that not only involves living and parasitizing at the expense of another, but is also a danger to the life of the host, as many types of parasites cause severe formsdisease in humans, livestock and agricultural crops.
The simplest human parasites have chosen almost all organs and systems of the human body, they develop quite actively and sometimes live in them for years. This symbiosis leads to the chronicity of the disease and a decrease in the effectiveness of the treatment process.
Routes of entry into the body:
- by the hands and the mouth;
- through the skin;
- contact;
- mother-to-fetus transmission;
- with bites of insects, animals;
A complete science that studies the phenomenon of parasitism, the biology of parasites and their area of distribution, diagnostics, methods of treatment and prevention of parasitic diseases.
The simplest pathogenic parasites that cause various forms of disease are found almost everywhere. These are fresh and salt water, soil, various household items and household items, public places. Protozoan infections are called protozoan or protozoan infections.
What are the simplest human parasites
The human body, like the body of any larger or smaller animal, is a very attractive object for parasitic lifestyles. In addition to protozoa, multicellular parasites (helminths) can inhabit the human body.
Depending on the habitat, the simplest species can be endogenous (living inside the human body) or exogenous (having chosen the skin as their place of residence). Sometimes as they develop, the parasites move around the body, choosing the most suitable habitat for a particular stage of development.
The microscopic size and the presence of a primitive structure allow the simplest parasites to survive and reproduce successfully under the most difficult conditions. All representatives of this species are characterized by a structure consisting of a single cell filled with cytoplasm with intracellular fluid, in which all metabolic processes take place with the participation of organelles (structures that perform various functions to maintain activityvital)
Movement functions can be performed by flagella, cilia and pseudopodia intended for this. The main process (food) is carried out in several ways:
- swallow through the mouth of the cell;
- circulate with pseudopods (pseudopods);
- absorption by the membrane surface.
Adverse conditions can become a signal for the formation of cysts resistant to the external environment of the membranes. They are necessary for the simplest human parasites to move from one host to another and can keep a prisoner inside the parasite for several years.
A reproductive cyst is characterized by the formation of a temporary thin shell, necessary for a protozoan for a short period of division.
Important!The simplest human parasites are the agents responsible for protozoan infections: giardiasis, trichomoniasis, sleeping sickness, amoebic dysentery, malaria.
Types of protozoan parasites
Regarding reproduction and movement, the nature of nutrition, there are 4 main classes of the simplest human parasites:
Flagellate
For example, lamblia, leishmania, trichomonas, trypanosomes. They have an elongated or pear-shaped oval body. They can have from 1 to 8 flagella of fine cytoplasmic growths, made up of the finest fibrils. They move forward with a flagellum, as if screwing into the space in front of them. They feed by both absorbing ready-made nutrients and absorbing them through the membrane. Reproduction occurs in most cases by simple division into two daughter cells. Flagellates can live in colonies of up to 10, 000 individuals.
Sporozoa
For example, the malaria plasmodia, Toxoplasma de Gondia. For representatives of this species of protozoa, a very complex developmental path is characteristic: from the carrier in human blood, then in the liver, where the parasite multiplies and affects red blood cells. Reproductive toxins cause disease in the human host. For the next development cycle, the pathogens must reenter the host's body, where the maturation of male and female cells and the formation of spores occur. After maturation, the spores are destroyed and the parasite re-enters the body of the host. The cycle repeats.
ciliates
For example, balantidia. For ciliates, movement with the help of eyelashes is characteristic. There are two nuclei in the body cell: the large nucleus controls all vital processes, for the small one the main role in the sexual side of the existence of protozoa is assigned. Reproduction occurs by dividing the cell in half, for most representatives of the species this happens daily, for some several times a day. The food is drawn into a special cavity (cell mouth) by the movement of the cilia, inside the cell, it is processed by the digestive vacuole, and the undigested residues are eliminated outside.
Sarcode
For example, amoeba is dysentery. It does not have a constant shape, forms many pseudopods, with the help of which it moves and catches food. It multiplies by simple division. It can exist in several forms: tissue, luminal, pre-cystic. The tissue form lives only in the intestines of a sick person. The rest of the forms can also be found in the body of the host.
Important!The primitive structure, the formation of cysts, the simplest mode of reproduction, the microscopic size, all these factors allow the simplest parasites to enter the most protected tissues of the human body and, in the absence of effectsunwanted, become the source of a number of serious and sometimes difficult to diagnose pathologies.
What diseases are caused by protozoan parasites
The parasitic lifestyle of the simplest microorganisms, in addition to the above factors, is also facilitated by their ability to breathe anaerobically, although many can use dissolved oxygen.
Diseases caused by protozoan parasites include:
Malaria
The main symptoms are fever attacks, joint pain, vomiting, anemia, convulsions. There may be an enlarged spleen. Malaria is characterized by a recurrent course of the disease, with periods of rest and exacerbation. Depending on the type of pathogen, the forms are distinguished: three-day, four-day and tropical. The disease is common in Africa and South Asia. For many centuries, as today, the main remedy for treatment has been quinine, a medicine made from the bark of cinchona. Despite the creation of synthetic analogues, deaths from infection occur in areas without access to modern medical care.
Amebiasis (dysentery amebiasis)
It is caused by the simplest parasitic amoeba of the dysenteric class of sarcodes. The infection can be intestinal and extra-intestinal (development in the liver). 7-10 days after infection, the first symptoms appear: abdominal pain, weakness, slight fever (up to +37. 5 ° C). About 10% may develop severe diarrhea, with traces of blood and mucus. One in three infected people develop a fever. It is characterized by an enlarged liver and, in some cases, an abscess of the liver. If treatment is not started on time, prolonged diarrhea causes dehydration, weakness and exhaustion of the patient's body. Epidemics of the disease are typical of countries with a hot climate.
Giardiasis
The disease is caused by the simplest of the class of flagellated lamblia. These parasites have 4 pairs of flagella and a sucker with which they attach themselves inside the small intestine. In case of infection, symptoms appear: pain and bloating in the upper part of the abdomen, rumbling and nausea, disturbance of the normal functioning of the intestines, skin lesions (atopic dermatitis), abnormal functioning of the gallbladder, general weaknessand loss of strength, poor appetite and sleep. Giardiasis is widespread in hot climate regions of Asia, Africa and Latin America.
Leishmaniasis
The disease is caused by a leishmania parasite of the flagellate class. The main symptoms of cutaneous and mucocutaneous leishmaniasis are lesions of the skin in the form of ulcers. With a mucocutaneous form, edema and deformity may occur. If the airways are involved, in rare cases it can be fatal. The visceral form is characterized by enlarged liver and spleen, fever and anemia. The disease is common in 88 countries, mainly in tropical and subtropical climates.
Trichomoniasis
The disease is caused by the parasite Trichomonas of the flagellate class. The genitourinary system is affected. The main symptoms in women are itching and burning, hyperemia of the external genitals, the presence of discharge with an unpleasant smell, sometimes there may be discomfort during intercourse and urination. In men, in most cases, the disease is asymptomatic, sometimes pain during urination and discharge, symptoms of prostatitis may appear.
Balantidiasis
The causative agent is a parasite of the ciliate balantidia class. A characteristic symptom is abdominal pain, diarrhea and the lining of the tongue. In acute cases of the disease, a rise in temperature, signs of general intoxication are possible. The infection can also be chronic, with intermittent periods of remission and exacerbation. In complicated cases, intestinal perforation and peritonitis are possible.
Toxoplasmosis
The disease is caused by the Toxoplasma parasite of Gondia, a sporozoan parasite. The characteristic symptoms of the disease are damage to the eyes, nervous system, heart muscles, enlarged lymph nodes, liver and spleen. It mainly takes place in a chronic form. Often the primary infection is very easy, under the guise of a common ARVI. After that, immunity appears forever, and further infection is impossible. The greatest danger is for the fetus during pregnancy: if the child survives, then with severe damage to the nervous system and eyes.
Sleeping sickness
The disease is caused by the simplest parasite of the flagellate class, the Gambian or Rhodesian trypanosome. The characteristic signs at the first stage are fever, headache and joint pain. After 7-20 days, the second phase of the disease begins: disturbances in the perception of the surrounding world begin, disturbances in the coordination of movements, numbness and sleep disturbances. The foci of the disease are localized in parts of tropical Africa, habitat of the main vector of tsetse fly infection;
Chagas disease
The causative agent is a parasite of the flagellated trypanosoma cruzi class. The main symptoms are fever, swollen lymph nodes, headache, and swelling at the bite site. At the initial stage, signs of the disease may be absent, and after 8-12 weeks, secondary symptoms may begin to develop in 30-40%: an increase in the ventricles of the heart, an expansion of the esophagus, an enlargement of thethe large intestine. The second stage of the disease can last 10 to 30 years after infection. The infection was most prevalent in Latin America.
Important!Most of the simplest parasites enter the human body if the basic rules of sanitation and personal hygiene are not observed.
Routes of infection
Penetration of any microorganism into the human body can occur through penetration through the skin or through natural openings. For most protozoan parasites in the environment, methods of human infection are limited to the four most common:
- Contact and housekeeping. This route of infection becomes accessible to the simplest organisms in violation of the rules of sanitation and personal hygiene. After all, most microorganisms, when they pass from the body of one host to the body of another, can form cysts and remain in this state until they enter a favorable environment, cthat is, inside a person. Infection can occur at any time: by shaking hands, using other people's household items (towel, linen, dishes), washing hands with dirty water (in a pond);
- Fecal-oral (giardiasis). In this case, the infection occurs when the parasite leaves the intestines with feces or vomit. If the rules of hygiene are not observed, the parasite enters the water, food or hands of the new host and enters the body. Poorly washed vegetables and herbs can also become a source of infection, and for children, dirty hands after playing in the sandbox or with pets;
- By contaminated food (toxoplasmosis). The meat of most animals, especially wild animals, can contain cysts of protozoan parasites, which, with insufficient heat treatment, enter the human body. Infection is also possible through dairy products that have not passed sanitary control and raw fish without sufficient heat treatment;
- Communicable (malaria, sleeping sickness). Infection occurs by transmission of the pathogen through the saliva of the carrier when bitten. The disease is transmitted by infected insects directly to a susceptible organism.
In addition to the main methods of infection, infection can occur in several other ways, which are much less common:
- Transplacental with penetration of protozoan parasites from the infected mother through the placenta to the fetus;
- Hemocontact when blood infected with parasites enters the patient's body (during medical procedures, drug injections, during sexual intercourse);
- Sexual infection only occurs through sexual contact.
Prevention
Prevention of infection with protozoan parasites includes, first of all, observance of all rules of sanitation and hygiene. The exclusion of the possibility of infection with parasites can be achieved by reasonably following a number of recommendations:
- Heat treatment of meat, dairy and fish products is sufficient (in accordance with the thermal regime according to the technology). Particular attention is paid to products which have not passed sanitary control;
- Thorough washing of fruits, vegetables, berries and herbs, preferably in boiling water. If heat treatment is not possible, especially to feed children, it is better to remove the skin;
- Regular medical examinations, especially if infection with protozoan parasites is suspected;
- Adherence to a sexual partner and refusal to use drugs;
- In the prevention of infections by insect bites, specific measures can be applied: the use of drugs, the destruction of mosquitoes, mosquito nets and repellents, the elimination of transgenic mosquitoes (resistant to malaria), the creation of'a vaccine.
Important!The level of resistance of the body is of great importance in preventing any infection, including the simplest human parasites. After all, if a cyst is found in unfavorable conditions, where it lacks nutrition or where immune cells constantly attack a foreign body, the parasite will die or leave the host's body.
There are a number of natural immunostimulating foods (garlic, ginger, broccoli, carrots, green tea) which, when consumed in a balanced way, can be of invaluable help to the body in strengthening immunity.
In addition, some products have a negative effect on the growth and reproduction of protozoa, especially those that have settled in the digestive tract: rice porridge and pearl barley, dried fruits, baked apples, vegetable oil, fruit compotes. vegetables. When treating pests, it is necessary to limit or completely exclude products that provoke fermentation processes: baked goods and sugar.
Currently, the pharmaceutical industry offers many expensive antiparasitic drugs. However, their effective use can be achieved only in combination with preventive measures and compliance with a certain diet, the composition of which can be consulted by a qualified specialist.
Do not forget about folk remedies, proven over time and many generations. In the case of a combination of all methods and methods under the supervision of a doctor, the parasites will have very little chance.
Conclusion
At the beginning of the 21st century, it can be noted that humanity has made great strides in the development of parasitology. The message about a new discovery of a particular drug is always accepted with joy by those in need of help and treatment today.
Even the simplest human parasites remain a serious problem in many countries, where the level of development of medicine and of society as a whole leaves much to be desired. There are many other places on our planet where diseases such as malaria, sleeping sickness, leishmaniasis and many more are endemic. And people are waiting and hoping that everyone has a chance to live disease free.
Parasitic diseases in our time are relevant, they require social interaction in all spheres of human life, aimed at improving the medical care of the population, observing the rules and standards of personal and public hygiene, to implementpreventive measures and sanitary and educational works, sanitation of natural foci of pathogenic organisms.
Currently, in many countries of the world, various scientific studies are carried out in the field of parasitology:
- development of scientific foundations and methods of surveillance of infectious and parasitic infections;
- study of the biological characteristics and variability of the agents responsible for the main diseases caused by protozoan parasites;
- quality control and environmental safety of meat and fish products;
- conduct basic research to study the development of pathogens of parasitic diseases, their genetic variability, ecology.