The simplest human parasites - species and diseases they cause

The simplest organisms that live in water bodies, soil and air of the Earth number up to 15, 000 species. Some of them are the oldest inhabitants of our planet. Over the millions of years that have passed since the appearance of the first living organism, most of the protozoa have hardly changed. But they 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, including in the human body.

Parasitism

This is a kind of complex relationship between two creatures, when one parasite uses another organism as a habitat or food resource.

The organism in which the parasite lives is called the host. It can be constant when the parasite goes through the entire cycle of its development and intermediate, when the pathogenic organism spends in it only a certain stage of the life cycle.

Parasitism among the 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, since 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.

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, soil, various household items and household items, public places. Protozoal infections are called protozoal 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.

According to the habitat, the species of the simplest 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 habitat most suitable for a particular stage of development.

Microscopic size and the presence of a primitive structure allow the simplest parasites to successfully survive and reproduce 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:

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

Unfavorable conditions can become a signal for the formation of cysts that are 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 up to several years.

The reproductive cyst is characterized by the formation of a thin temporary shell, which is necessary for the simplest protozoa 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

According to the method of reproduction and movement, the nature of nutrition, 4 main classes of the simplest human parasites are distinguished:

Flagellate

For example, lamblia, leishmania, trichomonas, trypanosomes. They have an elongated oval or pear-shaped body. They can have from 1 to 8 flagella of thin cytoplasmic outgrowths, consisting of the finest fibrils. They move forward with a flagellum, as if screwing 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.

Sporozoans

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 the red blood cells. Reproductive toxins cause disease in the human host. For the next developmental cycle, pathogens must again enter the host's body, where the maturation of male and female cells and the formation of spores occurs. After maturation, the spores are destroyed, and the parasite again enters the host's body. The cycle repeats itself.

Ciliates

For example, balantidia. For ciliates, movement with the help of cilia is characteristic. There are two nuclei in the cell of the body: the large nucleus controls all vital processes, for the small one the main role is assigned in the sexual side of the existence of protozoa. Reproduction occurs by dividing the cell in half, for most representatives of the species this happens daily, for some several times a day. Food is driven into a special depression (cell mouth) by the movement of cilia, inside the cell it is processed by a digestive vacuole, and not digested residues are removed outside.

Sarcode

For example, the amoeba is dysentery. It does not have a constant shape, forms many pseudopods, with the help of which it moves and grabs food. It multiplies 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 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 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 enlargement of the spleen. Malaria is characterized by a recurrent course of the disease, with periods of rest and exacerbation. Depending on the type of pathogen, 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 drug made from the bark of the cinchona tree. Despite the creation of synthetic analogs, deaths due to infection occur in areas without access to modern medical care.

Amoebiasis (dysentery amebiasis)

It is caused by the simplest parasite amoeba of the dysentery class of sarcodes. 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 treatment is not started on time, then prolonged diarrhea causes dehydration, weakness and depletion of the patient's body. Outbreaks of the disease are typical for 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 attach to the inside of the small intestine. When infected, symptoms appear: pain and bloating in the upper abdomen, rumbling and nausea, disruption of normal bowel function, skin lesions (atopic dermatitis), abnormalities in the functioning of the gallbladder, general weakness and loss of strength, poor 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 from 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 deformation may 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 from 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 during urination and discharge, symptoms of prostatitis may appear.

Balantidiasis

The causative agent is a parasite from the class of ciliates balantidia. A characteristic symptom is abdominal pain, diarrhea, and tongue lining. 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, enlargement of the lymph nodes, liver and spleen. It proceeds mainly 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 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 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, disruptions in the coordination of movements, numbness and sleep disturbance. Outbreaks of the disease are localized in certain regions of tropical Africa, the habitat of the main vector of the tsetse fly infection;

Chagas disease

The causative agent is a parasite from the class of flagellate trypanosoma cruzi. The primary symptoms are fever, swollen lymph nodes, headache, and swelling at the site of the bite. 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 the large intestine. The second stage of the disease can last for 10-30 years after infection. The infection was most 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.

Infection routes

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

1. Contact and household. This route of infection becomes available to the simplest organisms in case of violation of the rules of sanitation and personal hygiene. After all, most microorganisms, when 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 (towel, linen, dishes), washing hands with dirty water (in a pond);
2. Fecal-oral (giardiasis). In this case, infection occurs when the parasite leaves the intestines with feces or vomit. If the rules of hygiene are not followed, the parasite enters the water, food or hands of a 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 foods (toxoplasmosis). The meat of most animals, especially wild ones, can contain cysts of protozoan parasites, which, with insufficient heat treatment, enter the human body. Contamination is also possible through dairy products that have not passed sanitary control, and raw fish without sufficient heat treatment;
4. Transmissible (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 the penetration of protozoa 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, 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 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 compliance with the thermal regime according to the technology). Particular attention is paid to products that have not passed sanitary control;
• Thorough washing of fruits, vegetables, berries and herbs, preferably with boiling water. If heat treatment is impossible, especially for feeding children, it is better to remove the skin;
• Regular medical examinations, especially if there is a suspicion of infection with protozoan parasites;
• Adherence to one sexual partner and refusal to use drugs;
• In the prevention of infection from insect bites, specific measures can be applied: the use of medications, 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 the body's resistance. After all, if a cyst gets into unfavorable conditions, where it lacks nutrition or immune cells constantly attack a foreign object, then the parasite will either die or leave the host's body.

There are a number of foods that are natural immunostimulants (garlic, ginger, broccoli, carrots, green tea) that, when consumed in a balanced manner, can provide invaluable assistance 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, dried fruits, 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.

Currently, the pharmaceutical industry offers many expensive antiparasitic drugs. However, their effective use can be achieved only 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, time-tested and 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 mankind 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 still remain 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 more places on our planet where diseases such as malaria, sleeping sickness, leishmaniasis and many others are rampant. And people wait and hope that everyone has a chance to live without diseases.

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

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

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