Three pa no so ma. The structure and habitat of trypanosoma. Appearance of various forms of trypanosoma

Type: sarcoflagellates

Class: flagella (flagellata)

Order: protomonadina

Genus: Trypanosoma

Species: Trypanosoma rhodesiense

Species: Trypanosoma cruzi

Medical Significance:

Trypanosoma rhodesiense is the causative agent of African trypanosomiasis (sleeping sickness) Trypanosomacruzi is the causative agent of American trypanosomiasis (Chagas disease).

Anthropozoonotic disease with a transmissible mode of infection.

Life cycle:

Hosts:

T. rhodesiense:

Vector: tsetse fly

Definitive host: humans, mammals (ungulates).

T. cruzi:

Vector: triatomine bugs (genus: Triatoma, Rhodniuset Panstrongylus).

Definitive host: humans, rodents, primates, pets.

Localization: blood, lymph, cerebrospinal fluid, spleen, liver, brain and spinal cord ...

Sleeping sickness:

Increasing muscle weakness

Depression

exhaustion

Drowsiness, absent-mindedness, impaired coordination and orientation due to CNS damage

Chagas disease:

Often affects infants and patients with weak immunity.

Specific myocarditis

Bleeding into the meninges

Meningoencephalitis

Damage to internal organs

The disease occurs in both acute and chronic forms with a fatal outcome.

Laboratory diagnostics:

At the onset of the disease, it can be detected in the biopsy of the cervical lymph nodes and in peripheral blood. During the peak of the disease are found in the cerebrospinal fluid.

Prevention:

Public: destruction of carriers, treatment of patients.

Toxoplasma. Toxoplasma gondii.

Type: sporozoans

Class: Sporozoa

Order: blood spores (Haemosporidia)

Genus: Toxoplasma

Species: Toxoplasmagondii

Medical Significance: The disease is toxoplasmosis. Anthropose natural-focal.

Method of infection:

Alimentary route of infection - when eating raw meat, minced meat

Eating vegetables contaminated with oocysts (from the soil).

Infection through contact with the body fluids of a cat (while playing with it)

Transplacental infection

The core is red-violet located closer to the rounded end.

Hosts:

Definitive host: mammals from the cat family

Intermediate host: humans, many mammals, including cats, birds

Life cycle:

Oocytes enter the intestines of the intermediate host and dissolve, sporozoites turn into endozoites, enter the bloodstream through the intestinal wall and with macrophages are carried throughout the body (incomplete phagocytosis) and penetrate into the cells of the NS, liver, lung, spleen, muscles, heart ... where it begins asexual stage - endodyogony.

Clinic:

The disease proceeds latently (latently) in a chronic form.

With a decrease in immunity, encephalitis, myocarditis appear

t-body increased

damage to the liver, spleen → jaundice

swollen lymph nodes

m.b. skin rash

Laboratory diagnostics:

At the onset of the disease, it can be detected in the biopsy of the cervical lymph nodes and in peripheral blood. During the peak of the disease are found in the cerebrospinal fluid. Serological examination - immunological reactions.

Prevention:

Personal: taking medications

Public: destruction of carriers, treatment of patients.

The causative agent of sleeping sickness is the microorganism trypanosome, which is carried by tsetse flies in many countries of the African continent. Thousands of people die from this disease every year, and even modern medicine is not always able to help them recover.

The causative agents of African trypanosomiasis are 3 types of microorganisms:

• Trypanosoma brucei brucei- infects domestic and wild animals, human cases have not been reported, but are probable.
• Trypanosoma brucei gambiense- the causative agent of the Gambian, or West African, form of the disease in humans.
• Trypanosoma brucei rhodesiense causes the Rhodesian or East African type of disease in humans.

The two main types of the disease (Gambian and Rhodesian) differ in region of distribution and clinical picture, with the first form accounting for 98% of cases of sleeping sickness infection. It is characterized by a longer course and a gradual deterioration of the patient's condition.

The Rhodesian form of trypanosomiasis is distinguished by the rapid progression of the disease and all its signs; symptoms of CNS damage may appear already during the first year.

Methods of infection

There are several ways to transmit the causative agent of sleeping sickness to a person:

• bite of a tsetse fly (less often a triamtom bug or a fly-zhigalki) - in 80% of cases;
• during a blood transfusion from a sick person;
• intrauterine infection of the fetus from a sick mother.

Most often, flies can bite a person near water bodies, or on the banks of a river (West African species), or in places where tropical forests are cleared (East African). According to the incidence map, which shows the frequency of cases in various countries of the African continent, it is clearly visible in which regions there is the highest probability of infection with African trypanosomiasis.

On the territory of Russia and the CIS countries, infection with sleeping sickness is impossible, however, there are cases of infection of tourists who travel to African countries.

sleeping sickness vectors

The first clinical description of this disease was given in 1734 by the English physician Atkins, who diagnosed it among local residents in the Gulf of Guinea. But only in 1902, scientists P. Ford and J. Dutton were able to identify trypanosomes in the patient's blood, and also established the peddler of sleeping sickness - a blood-sucking fly Glossina palpalis(tsetse).

Tsetse flies are shade-loving insects that are active during the daytime. Habitat: thickets of plants along the banks of rivers and swamps in the regions of West and Central Africa. Females are viviparous, they lay one larva in the crevices of the earth, under the roots of trees. After that, the larva independently burrows into the soil, and after 5 hours a pupa is formed. After 3-4 weeks of development, an adult individual after pupation begins its first flight.

Most often, flies become carriers of the disease after they bite a sick animal. A fly infected with sleeping sickness releases 400,000 trypanosomes with saliva in one bite, and less than 400 are enough for human disease. After 10 days, a sick person himself becomes a source of invasion, which persists throughout his life.

At the 1st stage, the trypanosome enters the body of a fly after it bites a sick animal, then it multiplies by binary fission. After some time, trypomastigotes from the midgut pass into the salivary glands, where the process of transformation into epimastigotes takes place. Blood-sucking flies have a special chitinous proboscis that easily pierces the skin of not only humans, but also elephants or buffaloes.

After the penetration of the pathogen into the human body, the 2nd stage begins, diagnostic, which can already be diagnosed by specialists.

What happens after a person is infected

The disease is very common in areas where the tsetse fly lives - the African tropical savannas. Up to 40 thousand cases of the disease are registered annually in 36 countries of the hot continent.

After a person is bitten by a tsetse fly, the causative agent of sleeping sickness penetrates the skin, trypomastigotes transform into blood and enter the blood of their host, with which they are carried to all organs. A painful chancre knot is formed at the site of the skin puncture, disappearing gradually over several days, but after it, as a rule, a scar remains.

Trypanosama lives in the patient's skin for 1-2 weeks (incubation period), then it moves to the lymph and blood, cerebrospinal fluid, from where it spreads to the entire body. This is where it actively reproduces.

At the stage of the incubation period, trypanid spots appear on the body, arms and legs of the sick person, which have a pink or purple color. After the penetration of the pathogen into the blood, disturbances of the nervous and brain activity occur.

Signs and symptoms of the disease

At the stage of the incubation period, not all patients are aware of their disease, however, when moving to the next stage, the signs are already more characteristic and can be identified by doctors.

Symptoms of sleeping sickness are manifested in the second hemalymphatic stage:

• fever, fever, weakness and chills;
• painful subcutaneous edema, rashes;
• swollen lymph nodes, cervical lymphadenitis.

The second stage can last several months, and then, if left untreated, it turns into a neurological one.

Symptoms of sleeping sickness with damage to the central nervous system (meningoencephalitic stage):

• daytime sleepiness, confusion;
• headaches and joint pains, night sleep disturbances;
• tremor (trembling) of the limbs, tongue, unsteady gait;
• lethargy, changes in perception (impaired hearing, taste and smell);
• mental disorders (apathy to everything around);
• convulsions and epileptic seizures, coma.

If the patient did not turn to specialists and did not undergo timely treatment, then there is a high probability of death.

Diagnosis of the disease

If you suspect that a patient has African trypanosomiasis, you should immediately consult a doctor. First of all, the specialist makes a survey about the possibility of a person or his relatives staying in areas of the African continent in recent months, then he conducts a general examination of the patient's condition and sends him for tests.

Prognosis of the course of the disease:

• favorable if treatment is started before damage to the nervous system;
• with the manifestation of symptoms of CNS damage, the situation is more severe, and the prognosis depends on the state of the patient's body;
• lack of treatment - coma and 100% death.

Trypanosomiasis treatment

After the diagnosis of African trypanosome is made through laboratory tests, the doctor prescribes treatment. Special therapy is effective only in the initial acute period of the disease, because in the future, negative phenomena, expressed in cerebral consequences, already become irreversible, and modern medicine at the stage of CNS damage remains practically powerless.

Sleeping sickness is treated with medications:

• "Suramin" - is prescribed at the hemolymphatic stage with the Gambian form of the disease.
• Compounds of pentamidine and arsenic - used in the treatment of the Gambian form.
• "Melarsoprol" - a doctor prescribes for the meningoencephalitic stage of the disease, is highly effective for both forms of the disease.
• "Eflornithine" - for the treatment of patients at the 2nd stage of the Gambian form.
• "Nifurtimox" - is used in combination with "Eflornithine" to reduce the dosage and duration of treatment, thus reducing the adverse reactions of the patient's body.

All these drugs are highly toxic and often cause negative side effects on the patient's body. Specific therapy depends on the stage of the disease, the damage to the central nervous system and the brain. Long-term use of one drug does not give a positive result, because trypanosomes quickly adapt to it and begin to produce antigens.

Disease prevention

When visiting the African continent, in order not to get sick with sleeping sickness, it is necessary to exclude contact with the likely carrier - the tsetse fly and other insects in areas where there is a risk of infection.

Precautions and prevention of sleeping sickness:

• wear only light-colored clothes with long sleeves or special protection against mosquitoes;
• apply repellents that repel insects;
• to prevent infection, each tourist should be given a special vaccination before the trip, which is valid for 4 months.

Solving the problems of morbidity by the state

In African countries, especially in problem regions where there is a high probability of contracting sleeping sickness, measures are being taken to exterminate dangerous insects (tsetse flies). Screening diagnostics among the local population are also regularly carried out in order to identify sick people as early as possible and treat them in a timely manner.

The class of animal flagellates is divided into orders: 1) Kinetoplastids, 2) Diplomonads, 3) Trichomonas, 4) Polyflagellates, etc.

Detachment Kinetoplastida (Kinetoplastida)

rice. 1. Binary (1-3) and plural (4-6)
trypanosome division

rice. 2. Schemes of life cycles of pathogens of carotid
diseases of Rhodesian (A) and Gambian (B) types

The last stages of the disease are characterized by exhaustion, muscle weakness, depression, increasing drowsiness. There are two forms of sleeping sickness: Gambian and Rhodesian (Fig. 2). Sleeping sickness of the Gambian type lasts 6-10 years, the source of invasion is the person himself and domestic ungulates (goats, sheep, pigs), the causative agent is T. brucei gambiense.

rice. 3.
1 - core, 2 - flagellum,
3 - undulating membrane,
4 - kinetoplast.

Sleeping sickness of the Rhodesian type lasts 3-7 months, proceeds in a more acute form, ends in death. The source of invasion is wild ungulates (antelopes, rhinos, buffaloes), the causative agent is T. brucei rhodesiense. Laboratory diagnosis of sleeping sickness - microscopy of blood smears of the patient in order to detect trypanosomes (Fig. 3). Diseases, the causative agent of which is transmitted through the bite of a blood-sucking insect or tick, are called transmissible.

The causative agent of Chagas disease (Trypanosoma cruzi)- a species of trypanosomes found in South and Central America.

rice. 4. scheme of life
exciter cycle
Chagas disease

Symptoms of Chagas disease vary, depending on which organs are infected with trypanosoma. Damage to the heart muscle and related disorders of cardiac activity are more common. In young children, the disease is acute and often fatal. Laboratory diagnostics: a) microscopy of blood smears, b) xenodiagnostics (feeding uninfected bugs with the blood of a sick person, trypanosomes are found in mass quantities in the intestines of the bug on the 10-20th day).

rice. 5. Schemes of life cycles of pathogens of the skin (A)
and visceral (B) leishmaniasis

Laboratory diagnosis is based on the detection of leishmania in the bone marrow, the bone marrow is most often obtained by puncture of the sternum.

rice. 6. Giardia (lamblia
intestinalis):
1 - nuclei, 2 - flagella,
3 - suction disk.

Detachment of Diplomonads (Diplomonadida)

rice. 7. Trichomonas
(Trichomonas vaginalis):
1 - core, 2 - axostyle,
2 - flagella,
4 - undulating membrane.

Order Trichomonas (Trichomonadida)

rice. 8. Hypermastigidae
from the intestines of termites

Order Polyflagellates (Hypermastigida)

Hypermastigids, or polyflagellates, are inhabitants of the intestines of wood-eating insects. Representatives of this order have many flagella that form bundles (Fig. 8). In addition to flagella, they can form pseudopodia to capture pieces of wood. Inside the cell - one or more axostyles.

Polyflagellates are useful symbionts of termites. These flagellates secrete the enzyme cellulase, which digests fiber. Termites do not synthesize this enzyme, and without flagellates they are not able to digest wood.

About what trypanosome is, and how exactly the symptoms of infection with its African and American varieties are manifested, and will be discussed in our article.

Trypanosomiasis is an anthroponotic disease. It means that the natural reservoir where the trypanosome lives is precisely the person. However, this does not eliminate the possibility of infecting domestic animals such as horses, camels, donkeys, cattle and small cattle.

Trypanosomes spread through the blood, lymph and cerebrospinal fluid

Inside the single trypanosome cell is the cytoplasm, in which the nucleus and mitochondria float. Trypanosomes are characterized by a body containing a storehouse of genetic information - kinetonucleus, and kinetosome. The trypanosome moves with the help of flagella, whose growth is regulated by the kinetosome.

In addition, trypanosoma can take a flagellate-free form - amastigote, and an intermediate form of development - epimastigote, in which the flagellum is not so well expressed. The structure of trypanosoma Kruzi (see photo below) is distinguished by a curved body shape and a longer flagellum.

Varieties of trypanosomes

Trypanosome structure

Trypanosome development cycle

In contact with

Trypanosoma sp. among red blood cells

The taxonomy of trypanosomes is presented as follows:

• Genus: Trypanosoma;
• Order: Trypanosomatida;
• Class: Kinetoplastid;
• Type: Euglenozoa;
• Kingdom: Eukaryotes.

Morphological characteristics

Reproduction is asexual and is carried out by longitudinal mitosis. As a result, two daughter cells are formed from one parent cell.

Life cycle features

Tripanosoma life cycle diagram

The life cycle of a trypanosome consists of two stages: in the body of an insect - a carrier (invasive stage) and a person (definitive host).

The development cycle of trypanosomes ends with this stage - with active reproduction, general intoxication with waste products and damage to organ tissues occurs, which causes an acute manifestation of symptoms and can lead to death.

Species diversity

Depending on the disease caused, the region of distribution, there are different types of trypanosomes. The most common types are:

• trypanosoma brucea;
• trypanosoma gambia (gambiense);
• trypanosoma cruzi (American);
• Trypanosoma Rhodesian (East African).

Some diseases provoke different types of trypanosomes, but there are pathologies provoked by one type of pathogen.

Chagas disease

It got its name in honor of the Brazilian bacteriologist who discovered it. The causative agent is Trypanosoma cruzi. It provokes an inflammatory process in the heart muscle and the membranes of the brain. It spreads with the saliva of the triatomic bug - a hematophagus during a bite. Infection is also possible if infected insect feces get into the bite site or into the combed area of ​​the skin.

Endemic pathology is considered for the regions of South and Central America.

Tumor of the cervical glands in a man with sleeping sickness

This pathology is most common in Africa. The causative agent can be trypanosoma gambiense, brucei and rhodesian. Infection occurs as a result of contact with the infected saliva of the intermediate host (tsetse fly). Depending on the region, the pathogens may differ: in the eastern part of the continent, the Rhodesian is more common, while in the western part, the Gambian. Statistics say about 40,000 infections per year. However, you need to understand that statistics only have data on registered patients, and at the same time there are many patients who are not provided with medical care. In such cases, it is possible to appeal only with estimated figures, which are approximately indicated up to 300,000. At the same time, about 50,000,000 people live in conditions of increased risk of infection.

Also, the hemolymphatic stage may be accompanied by the following symptoms:

• general weakness;
• weight loss;
• accelerated heartbeat;
• pain in the joints;
• liver enlargement;
• swelling of the parotid salivary glands.

This stage may alternate between latent periods and exacerbations. It can last up to several years.

Upon the onset of the third stage, the central nervous system is damaged, during which the degeneration of the nervous tissue occurs. This is accompanied by violations of the musculoskeletal system, all organ systems. Psychiatric disorders may appear.

Diagnosis and therapy

Treatment is aimed at destroying mature individuals in the human body and reducing residual effects.

The later the disease is detected, the more harm can be done.

Preventive measures are aimed at mass examinations of people living in the area of ​​distribution of the carrier. Measures are also being taken to reduce the number of carriers.