The simplest human parasites: species and diseases they cause

The simplest organisms that live in Earth's bodies of water, soil, and air number up to 15, 000 species. Some of them are the oldest inhabitants of our planet. During the millions of years that have passed since the first living organism appeared, most protozoa have barely changed. But they learned to adapt well to new living conditions and to find ways to survive. One of the most obvious forms of existence for these organisms has become parasitism, even in the human body.

Parasitism

This is a kind of complex relationship between two creatures, when a parasite uses another organism as a 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 in it and intermediate, when the pathogenic organism passes only a certain stage of the life cycle in it.

Parasitism between protozoa is a type of interaction that involves not only living and parasitizing at the expense of another, but also posing a danger to the life of the host, as many types of parasites cause severe forms of disease 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 it for years. This symbiosis leads to the chronicity of the disease and a decrease in the effectiveness of the treatment process.

Routes of entry to the body:

• through the hands and mouth;
• through the skin;
• Contact;
• transmission from mother to fetus;
• with insect bites, animals;

A comprehensive science that studies the phenomenon of parasitism, the biology of parasites and the area of their distribution, diagnoses, 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 more or less large animal, is a very attractive object for parasitic life patterns. 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 a place of residence). Sometimes, as they develop, the parasites move through 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 vital activity) .

Movement functions can be performed by flagella, cilia and pseudopods intended for this. The main process (food) is carried out in several ways:

• swallow through the mouth of the cell;
• flow with pseudopods (pseudopods);
• absorption by the membrane surface.

Unfavorable conditions can become a sign of cyst formation resistant to the external environment of the membranes. They are necessary for the simplest human parasites to move from host to host and can hold a prisoner within the parasite for up to several years.

A reproductive cyst is characterized by the formation of a thin temporal layer, which is necessary for a protozoan for a short period of division.

Important!The simplest human parasites are the causative agents of protozoan infections: giardiasis, trichomoniasis, sleeping sickness, amoebic dysentery, malaria.

Types of protozoan parasites

By the way of 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 oval or pear-shaped body. They may have 1 to 8 flagella of thin cytoplasmic outgrowths, consisting of the finest fibrils. They advance with a scourge, as if curled up in the space in front of them. They feed by 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, malaria plasmodia, Toxoplasma de Gondia. For representatives of this species of protozoa, a very complex development path is characteristic: from the carrier to human blood, then to the liver, where the parasite multiplies and affects red blood cells. Reproductive toxins cause disease in the human host. For the next developmental cycle, pathogens must re-enter the host's body, where maturation of male and female cells and spore formation occur. After maturation, the spores are destroyed and the parasite enters the host's body again. The cycle repeats.

Ciliates

For example, balantidia. For ciliates, movement with the help of cilia is characteristic. There are two nuclei in the body cell: the large nucleus controls all vital processes, the small one is assigned the main role on the sexual side of the existence of protozoa. Reproduction occurs by dividing the cell in half, for most representatives of the species this occurs daily, sometimes several times a day. The food is led to a special cavity (cell mouth) by the movement of the cilia, inside the cell it is processed by the digestive vacuole and the undigested waste is eliminated outside.

Sarcode

For example, amoeba is dysentery. It does not have a constant shape, it forms many pseudopods, with the help of which it moves and grabs food. It is multiplied by simple division. It can exist in several forms: tissue, luminal, precystic. The tissue form lives only in the intestines of a sick person. The rest of the forms can also be found in the host's body.

Important!The primitive structure, the formation of cysts, the simplest form of reproduction, the microscopic size - all these factors allow the simplest parasites to penetrate the most protected tissues of the human body and, in the absence of adverse effects, become the source of a number of serious and sometimes difficult to diagnose pathological conditions.

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 attacks of fever, joint pain, vomiting, anemia, seizures. 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 days, four days and tropical. The disease is common in Africa and South Asia. For many centuries, like today, the main treatment remedy has been quinine, a drug made from the bark of the cinchona tree. Despite the creation of synthetic analogues, deaths from infection occur in areas without access to modern medical care.

Amebiasis (amoebiasis dysentery)

It is caused by the simplest parasitic amoeba of the dysentery class of sarcodes. The infection can be intestinal and extraintestinal (development in the liver). 7-10 days after infection, the first symptoms appear: abdominal pain, weakness, low-grade fever (up to + 37. 5 ° C). About 10% may develop severe diarrhea, with traces of blood and mucus. One in three infected people has a fever. It is characterized by an enlarged liver and, in some cases, a liver abscess. If treatment is not started in time, prolonged diarrhea causes dehydration, weakness and exhaustion of the patient's body. Outbreaks of the disease are typical of countries with hot climates.

Giardiasis

The disease is caused by the simplest of the class of flagellate lamblia. These parasites have 4 pairs of flagella and a suction disc, with which they adhere to the interior of the small intestine. When infected, symptoms appear: pain and swelling in the upper abdomen, noise and nausea, alteration of the normal functioning of the intestines, skin lesions (atopic dermatitis), abnormalities in the functioning of the gallbladder, general weakness and loss of strength, appetite and sleep. Giardiasis is widespread in regions with hot climates in 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 skin lesions in the form of ulcers. With a mucocutaneous form, edema and deformation can occur. If the respiratory tract is affected, in rare cases, it can be fatal. The visceral form is characterized by an enlarged liver and spleen, fever, and anemia. The disease is common in 88 countries, mainly with tropical and subtropical climates.

Trichomoniasis

The disease is caused by the Trichomonas parasite of the flagellate class. The genitourinary system is affected. The main symptoms in women are itching and burning, hyperemia of the external genital organs, the presence of discharge with an unpleasant odor, sometimes there may be discomfort during sexual intercourse and urination. In men, in most cases, the disease is asymptomatic, sometimes pain when urinating and on discharge, symptoms of prostatitis may appear.

Balantidiasis

The causative agent is a parasite of the ciliated balantidia class. A characteristic symptom is abdominal pain, diarrhea, and the lining of the tongue. In acute cases of the disease, an increase 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 de Gondia parasite, a sporozoan parasite. Characteristic symptoms of the disease are damage to the eyes, nervous system, heart muscles, enlarged lymph nodes, liver, and spleen. It proceeds mainly chronically. Primary infection is often very easy, under the guise of a common ARVI. After that, immunity appears forever, and further infection is impossible. The greatest danger is to 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 of the first stage are fever, headache, and joint pain. After 7-20 days, the second phase of the disease begins: alterations in the perception of the surrounding world, alterations in the coordination of movements, numbness and sleep disturbances begin. Outbreaks of the disease are located in certain regions of tropical Africa, the habitat of the main vector of tsetse fly infection;

Chagas disease

The causative agent is a parasite of the flagellated class of trypanosome cruzi. The main symptoms are fever, swollen lymph nodes, headache, and swelling at the site of the bite. In the initial stage, the signs of the disease may be absent, and after 8-12 weeks, secondary symptoms may begin to develop by 30-40%: an increase in the ventricles of the heart, an expansion of the esophagus, a enlargement of the large intestine. The second stage of the disease can last 10 to 30 years after infection. The infection was more widespread in Latin America.

Important!Most of the simplest parasites enter the human body if basic rules of sanitation and personal hygiene are not followed.

Pathways of infection

Penetration of any microorganism into the human body can occur through penetration through the skin or natural openings. For most protozoan parasites found in the environment, human infection methods are limited to the four most common:

1. Contact and home. This route of infection becomes available to the simplest organisms in violation of the rules of sanitation and personal hygiene. After all, most microorganisms, passing 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, that is, inside a person. Infection can occur at any time: when shaking hands, when using other people's household items (towel, bedding, dishes), when washing hands with dirty water (in a pond);
2. Fecal-oral (giardiasis). In this case, the infection occurs when the parasite leaves the intestines with feces or vomit. If hygiene rules are not followed, 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;
3. Through contaminated food (toxoplasmosis). The meat of most animals, especially wild ones, can contain cysts of protozoan parasites that, with insufficient heat treatment, enter the human body. Infection is also possible through dairy products that have not passed the sanitary control and raw fish without sufficient heat treatment;
4. Communicable (malaria, sleeping sickness). The 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 the penetration of parasitic protozoa from the infected mother through the placenta to the fetus;
• Hemocontact when blood infected with parasites enters the patient's body (during medical procedures, narcotic injections, during sexual intercourse);
• Sexual infection occurs only through sexual contact.

Prevention

Prevention of infection by protozoan parasites includes, first of all, compliance with all rules of sanitation and hygiene. Exclusion of the possibility of infection by parasites can be achieved by reasonably following a series of recommendations:

• The heat treatment of meat, dairy and fish products is sufficient (according to the heat regime according to the technology). Special attention is paid to products that have not passed the sanitary control;
• Thoroughly wash fruits, vegetables, berries and herbs, preferably with boiling water. If heat treatment is impossible, especially to feed children, it is better to remove the skin;
• Periodic medical examinations, especially if there is a suspicion of infection by protozoan parasites;
• Adherence to a sexual partner and refusal to use drugs;
• In the prevention of infection by insect bites, specific measures can be applied: the use of medications, the destruction of mosquitoes, mosquito nets and repellants, the elimination of transgenic mosquitoes (resistant to malaria), the creation of a vaccine.

Important!Of great importance in preventing any infection, including the simplest human parasites, is the level of resistance of the body. After all, if a cyst enters unfavorable conditions, where it lacks nutrition or immune cells constantly attack a foreign object, then the parasite will die or leave the host's body.

There are a number of foods that are natural immunostimulants (garlic, ginger, broccoli, carrots, green tea) which, when consumed in a balanced way, can provide invaluable help to the body in enhancing 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 and pearl barley porridge, nuts, baked apples, vegetable oil, stewed vegetables. When treating parasites, it is necessary to limit or completely exclude products that provoke fermentation processes - baked goods and sugar.

Today, the pharmaceutical industry offers many expensive antiparasitic drugs. However, its effective use can only be achieved in combination with preventive measures and compliance with a certain diet, the composition of which can be consulted by a qualified specialist.

Don't forget about home remedies, proven over time and from many generations. In the case of a combination of all methods and methods under the supervision of a doctor, parasites will have very little chance.

conclusion

At the beginning of the 21st century, it can be noted that humanity has achieved a lot in the development of parasitology. The message about a new discovery of a particular drug is always happily accepted by people who today need help and treatment.

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 more places on our planet where diseases like malaria, sleeping sickness, leishmaniasis, and many others are rampant. And people hope and hope that everyone has a chance to live disease-free.

Parasitic diseases in our time are relevant, they require social interaction in all areas of human life, aimed at improving medical care for the population, observing the rules and regulations of personal and public hygiene, carrying out preventive measures and sanitary tasks. and educational, sanitation. of natural foci of pathogenic organisms.

Currently, in many countries of the world, various scientific studies are being carried out in the field of parasitology:

• development of scientific bases and methods for the monitoring of infectious and parasitic infections;
• study of the biological characteristics and variability of the causative agents of the main diseases caused by protozoan parasites;
• quality control and environmental safety of meat and fish products;
• conduct fundamental research to study the development of parasitic disease pathogens, their genetic variability, ecology.