Diseases caused by parasites

There are over 200 different species of parasites. Carriers of the eggs of these organisms in most cases are insects, and native mammals.

diseases caused by parasites

In the human body at the same time can live up to 5 kinds of parasites. About some he may not even be aware, but others represent an enormous danger to life.


Trypanosoma is a parasitic single-celled microorganism that can live in the human body and cause serious disease. Their parasitism is obligate in nature, so a living organism is the only place of living trypanosomes. Diseases caused by these single-celled, combined into 1 group called trypanosomiasis.

The most common and studied types of the following trypanosomes:

  • brucei;
  • cruzi.


Trypanosoma is a unicellular parasite, is spread with flies Glossina (tsetse fly) that causes African trypanosomiasis.

Depending on the areas of greatest distribution are the following subtypes:

  • brucei. The causative agent of African trypanosomiasis in animals (rarely in humans);
  • equinum. The pathogen is widely distributed in Northern and southern Africa (recorded isolated cases of infection in Italy). Parasitic on horses and mules. Causes so-called disease that is transmitted sexually, symptoms of pronounced swelling of the genital organs of animals;
  • gambiense. The pathogen is widespread in Central and West Africa, causes the chronic form of sleeping sickness in humans;
  • rhodesiense. Lives in southern and Eastern Africa and causes an acute form of sleeping sickness in humans (rare in animals).

A distinctive feature of the trypanosomes from other parasites is the presence of these unicellular ability to circumvent the human immune defense.

The parasite is an elongated cell that consists of cytoplasm and nucleus, at certain stages has a long flagellum, which functions as a motor organ. The size of the parasite varies from 10 to 70 µm. Reproduction occurs vegetatively (longitudinal division).

The structure of the trypanosomes varies depending on in the body of a host (intermediate or final) is located.

There may be 2 phases of the developmental cycle of Trypanosoma brucei:

  1. A special stage. Once in the intestine of the carrier in the form of parasites, micro-organisms turn into other parasites, localized in the saliva of the insect. In a special section starts on active cell division, which generates a vast population of parasites. Such a form of existence of trypanosomes in the body of an intermediate host, it is an elongated cell with a short flagellum and implicitly pronounced undulating membrane that functions as a body motion as the flagellum.
  2. Trypanosomatidae. This parasite develops and moves in the body of the definitive host. The appearance is somewhat different from the previous stage – more elongated body, longer than the flagellum, the membrane is more active.

Trypanosoma cruzi

The vectors are bugs. Causes Chagas disease (American trypanosomiasis). Habitat – South America (sometimes Central).

The life cycle of Trypanosoma cruzi is represented by 3 stages of development:

  1. Stage in the life cycle of protozoa of the genus Trypanosoma. In the form of parasites, the pathogen enters the intestine of a bug, where after the bed bugs bite an infected person;
  2. The next stage in the life cycle of protozoa of the genus Trypanosoma. In the intestine of the bug, the parasite develops another parasite and gets on the skin of a person with feces;
  3. Mastigos. Once in the epithelial and later the top layer of skin or mucous membranes, the pathogen changes its cellular structure on the parasite. Mastigos has a round shape, is characterized by the absence of flagella and real estate. In this form it is propagated, then repeats the cycle first emerging in the following form of the parasite migrates to other tissues, develops into a mastigos, etc.
types of parasites

The causes of human infection

A person can be infected African American or parasites through interaction with insect vectors.

The habitat of these insects are concentrated in tropical and subtropical areas of Africa and South America.

Intermediate hosts for the parasites in most cases are a particular bug (in South America, mainly in Argentina) and the tsetse fly (in Africa).

Bug Triatominae is one of the most dangerous insects for man. Its bite is fatal in 9 cases out of 10.

To move into the body of the definitive host microorganism can 3 ways:

  • directly through the insect bite;
  • blood transfusions;
  • in utero.

At risk of infection include primarily people in poor and densely populated regions of Africa and South America. The lack of personal hygiene, location of housing in woodland, dilapidated housing, dirt – all this triggers infestation.

Tourists must remember that vaccines against infection by such parasites do not exist!

For information, the risk of infestation to a minimum, tourists exotic countries of South America and Africa should observe the following rules:

  • be sure to wash fruits under running water before use;
  • wear maximally closed clothes, especially in the dark;
  • applied to the skin preparations containing insect repellent;
  • avoid direct contact of bare skin with tall grass/bushes;
  • not to visit old buildings;
  • sleep under the canopy for additional protection from insects to the bed.

IMPORTANT! Often the cause of infestation is failure to follow simple measures of self-defense!

The pathogenesis of the disease

Sleeping sickness

African trypanosomiasis. Depending on the type of pathogen are distinguished:

  • the acute form;
  • a chronic form.

The Tsetse fly, which carries trypanosomiasis, is not poisonous. Its danger lies in the transfer of pathogenic organisms and invasion of a human.

In 98% of cases of sleeping sickness occurs in primary chronic form.

After penetration into the mucosa or in the skin layer, starts the incubation period, which lasts up to 3 weeks. At this time, the parasites they share, and then penetrate to the lymph nodes (by hitting them) and the blood current which reach the tissues of the nervous system. In the chronic form the disease is much slowed down and is hidden, so the symptoms may come on slowly and people do not suspect the infection for quite a long time (from 1 month to several years). The acute course of the disease involves the primary aggressive onset of symptoms, resulting in easier diagnosed, but very rare.

Chagas Disease

American trypanosomiasis. The principle of distribution of trypanosomes in the human body similar to sleeping sickness, but in this case, the parasites cause degenerative changes mainly in the heart and esophagus (rarely in the liver, adrenal glands) and poisoning the body with toxins – products of its life. The incubation period lasts up to 2 weeks. Next comes the acute phase of the disease, which is manifested mild symptoms. 2-3 months after the infection, the disease becomes chronic. Symptoms are absent or almost invisible. In blood banks in Latin America the percentage of infection of blood parasites is higher than AIDS and can be up to 52%.


African trypanosomiasis

The bite of the tsetse fly is formed by a lit hearth, with a diameter of 10 cm, which is characterized by:

  • itching;
  • redness;
  • hyperemia;
  • edema.

In the case of primary chronic version, the symptoms can accompany the person for years and are expressed as:

  • the increase in cervical lymph nodes;
  • hyperthermia;
  • weakness.

In the acute phase by the above symptoms are added:

  • inflammation of the brain and the following the swelling;
  • inhibited condition, fades into a coma.

American trypanosomiasis

After being bitten by this bug to defecate in the wound, feces contain parasites that enter through the skin into the human body, because the bitten place is accompanied by severe itching and itchy person.

On the site of the bite formed a focus of infection, with a diameter of 15 cm and is accompanied by redness and swelling. After the end of the incubation period, manifested the first symptoms of the disease:

  • fever;
  • migraine;
  • vomiting;
  • pain in the heart.

The disease leads to CNS (Central nervous system) and ANS (autonomic nervous system), degenerative changes in the heart, esophagus, liver, and adrenal glands.


The major point of primary diagnosis of trypanosomiasis is the collection of anamnesis to identify the risk of infection (recent trip to Africa and Latin America, the presence of primary symptoms).

For more in-depth diagnostic measures resorted to deep research:

  • xenodiagnosis;
  • biological sample (blood of the intended introduction of the patient into the abdominal cavity of experimental animals);
  • sero-diagnosis;
  • immunological reactions (in the chronic form of Chagas disease in blood will be detected in serum immunoglobulin G in acute – M);
  • lumbar puncture;
  • study of the punctate of lymph nodes, blood.

The diseases caused by these parasites are often disguised as other diseases, so you must spend a number of independent from each other research to accurately identify the infestation.


Vaccination against invasion of pathogenic microorganisms is not provided.

Measures of prevention include:

  • the destruction of the carriers of parasites;
  • a thorough study of donor blood;
  • timely processing of housing insecticidal solutions;
  • improving the quality of life of the population in poor areas, which are the habitat of insect vectors.

Besides the obvious measures to maintain hygiene of used products, as well as the above precautions, med. institutions are required to conduct educational work among the population. Must be available to convey to all segments of society, what is a parasite which causes sickness and what effects entail.

To protect themselves from infection with these parasites is impossible. Keep this in mind when deciding to go on a tourist trip to Latin America or Africa.

diagnosis and treatment

Do not neglect precautions, even if you think that they are not effective or there is no danger.