The simplest human parasites: species and diseases they cause

The simplest organisms that live in the water bodies, soil and air of the Earth 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 remained virtually unchanged. But they have learned to adapt well to new living conditions and find ways to survive. One of the most obvious ways of existence for these organisms has become parasitism, even in the human body.

Parasitism

This is a type 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 spends only a certain stage of its life cycle in it.

Parasitism among protozoa is a type of interaction that involves not only living and parasitizing at the expense of another, but also poses a danger to the life of the host, as many types of parasites cause severe forms of disease in humans, in the livestock and agricultural crops.

The simplest human parasites have chosen almost all the organs and systems of the human body, develop quite actively and sometimes live in it for years. This symbiosis leads to the chronicity of the disease and to a decrease in the effectiveness of the treatment process.

Ways of entry into the body:

• through the hands and mouth;
• through the skin;
• contact;
• transmission from mother to fetus;
• with bites of insects, animals;

A comprehensive science that studies the phenomenon of parasitism, the biology of parasites and the area of their distribution, diagnostics, methods of treatment and prevention of parasitic diseases.

The simplest pathogenic parasites that cause various forms of diseases are found almost everywhere. These are fresh and salt water, earth, various household items and household items, public places. Protozoal infections are called protozoal or protozoal 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 the life patterns of parasites. In addition to protozoa, multicellular parasites (helminths) can inhabit the human body.

Depending on the habitat, the simpler species can be endogenous (living inside the human body) or exogenous (having chosen the skin as a place of residence). Sometimes, as they develop, 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 in 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)

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

• mobile mouth swallowing;
• flow around with pseudopodia (pseudopodia);
• absorption by the membrane surface.

Unfavorable conditions can become a signal for the formation of cysts resistant to the external environment of the membranes. They are needed for simpler human parasites to move from host to host and can hold a prisoner inside the parasite for up to several years.

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

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

Types of protozoan parasites

Speaking of reproduction and movement, the nature of nutrition, there are 4 main classes of the simplest human parasites:

scourged

For example, lamblia, leishmania, trichomonas, trypanosomes. They have an elongated oval or pear-shaped body. They can have 1 to 8 flagella of thin cytoplasmic growths, consisting of the finest fibrils. They move forward with a flagellum, as if spinning into the space in front of them. They feed both by absorbing ready-made nutrients and by 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 of Gondia. For representatives of this species of protozoa, a very complex path of development is characteristic: from the carrier into the human blood, then into 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 once again enter the host's body, where the maturation of male and female cells and the formation of spores take place. After ripening, the spores are destroyed and the parasite enters the host's body again. The cycle repeats itself.

ciliates

For example, balantids. For ciliates, movement with the help of eyelashes is characteristic. There are two nuclei in the cell of the body: the large nucleus controls all vital processes, for the small one it is assigned the main role in 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, some several times a day. Food is guided into a special cavity (cellular mouth) by the movement of the cilia, inside the cell it is processed by the digestive vacuole, and undigested residues are removed to the 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 multiplies by simple division. It can exist in different forms: tissue, luminal, precistic. The shape of the tissue 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 way of reproduction, microscopic size, all these factors allow the simplest parasites to penetrate into 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 simpler microorganisms, in addition to the aforementioned 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, 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 therapeutic remedy has been quinine, a drug obtained 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.

Amoebiasis (amoebiasis dysentery)

It is caused by the simplest parasitic amoeba of the dysentery class of sarcods. 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. Every third infected person develops a fever. It is characterized by an enlarged liver and, in some cases, a liver abscess. If the treatment is not started in time, prolonged diarrhea causes dehydration, weakness and impoverishment of the patient's body. Epidemics of the disease are typical of countries with warm 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 attach themselves to the inside of the small intestine. When infected, symptoms appear: pain and swelling in the upper abdomen, rumbling and nausea, disruption of normal bowel function, skin lesions (atopic dermatitis), abnormal functioning of the gallbladder, general weakness and loss of strength, poor appetite and sleep. Giardiasis is widespread in regions with warm climates in Asia, Africa and Latin America.

leishmaniasis

The disease is caused by a parasite of the leishmania of the class of flagellates. 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 involved, 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 discharging, symptoms of prostatitis may appear.

balantidiasis

The causative agent is a parasite of the balantidia class of ciliates. 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 proceeds in a chronic form. Often, 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 to the fetus during pregnancy: if the baby survives, then with severe damage to the nervous system and eyes.

Sleeping sickness

The disease is caused by the simplest parasite of the class of flagellates, the Gambian or Rhodesian trypanosome. The characteristic signs of the first phase 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, disruptions in the coordination of movements, numbness and sleep disturbances begin. The foci of the disease are located in some regions of tropical Africa, habitat of the main vector of tsetse fly infection;

Chagas disease

The causative agent is a parasite of the class of trypanosoma cruzi flagellates. The main symptoms are fever, swollen lymph nodes, headache and swelling at the site of the bite. In 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 enlarged large intestine . The second stage of the disease can last for 10-30 years after infection. The infection was more prevalent in Latin America.

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

Routes of infection

The 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 family. This route of infection becomes available to simpler organisms in violation of the rules of hygiene 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, in other words, inside a person. Infection can occur at any time: when shaking hands, using other people's household items (towels, linen, dishes), washing hands with dirty water (in a pond);
2. Fecal-oral (giardiasis). In this case, the infection occurs when the parasite leaves the intestine with stool or vomit. If the hygiene rules are not followed, the parasite enters the water, food or hands of the new host and enters the body. Even poorly washed vegetables and herbs can 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 parasitic protozoa, which, with insufficient heat treatment, enter the human body. Infection is also possible through dairy products that have not passed health checks and raw fish without sufficient heat treatment;
4. Communicable (malaria, sleeping sickness). Infection occurs by transmission of the pathogen through the bearer's saliva when bitten. The disease is transmitted from infected insects directly to a susceptible organism.

In addition to the main methods of infection, infection can occur in many 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 parasitic-infected blood enters the patient's body (during medical procedures, narcotic injections, during sexual intercourse);
• Sexual infection occurs only through sexual contact.

Prevention

Prevention of infection with protozoan parasites includes, first of all, compliance with all sanitary rules. The exclusion of the possibility of parasitic infection can be achieved by reasonably following a number of recommendations:

• Heat treatment of meat, dairy and fish products is sufficient (in compliance with the heat regime according to the technology). Particular attention is paid to products that have not passed the health check;
• Thorough washing of fruits, vegetables, berries and herbs, preferably with boiling water. If heat treatment is impossible, especially for feeding babies, it is better to remove the skin;
• Regular medical examinations, especially if a protozoal parasite infection is suspected
• 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 drugs, the destruction of mosquitoes, mosquito nets and repellents, the elimination of transgenic mosquitoes (resistant to malaria), the creation of a vaccine.

Important!Of great importance in the prevention of 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, the parasite will die or leave the host's body.

There are numerous natural immunostimulating foods (garlic, ginger, broccoli, carrots, green tea) which, if consumed in a balanced way, can provide invaluable help to the body to strengthen the immune system.

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, dried fruit, cooked 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.

Currently, the pharmaceutical industry offers many expensive anti-parasite drugs. However, their effective use can only be achieved in combination with preventive measures and adherence to a certain diet, the composition of which can be consulted by a qualified specialist.

Do not forget about folk remedies, tested 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 little chance.

Conclusion

At the beginning of the 21st century, it can be seen 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 need help and treatment today.

Simpler human parasites are still a serious problem in many countries, where the level of development of medicine and 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 others are rampant. And people are waiting and hoping that everyone has a chance to live without disease.

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

At the moment, in many countries of the world, various scientific studies are underway in the field of parasitology:

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