Leishmania

Leishmania are pathogens of protozoal infection, which causes damage to the outer covers, or internal organs (disease - leishmaniasis ).

Leishmania represents the family of trypanosomide (from the detachment of protonmonadids), the class of flagellates, the type of protozoa. It is an intracellular parasitic microorganism that develops in the body of certain insects, and through them is transmitted to humans or animals.

Leishmania are recognized as causative agents of internal and cutaneous leishmaniasis - a serious infectious disease that occurs with ulcerative skin and / or internal organs.

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Structure of Leishmania

Leishmania can be represented by two forms - intracellular amastigota and promastigot (flagellar form).

Amastigot has rounded outlines, from 2.5 to 5 μm in diameter, located in the middle of the parasitophore vacuole of the macrophage. A clearly marked nucleus and kinetonucleus are observed, characterized by vacuolated cytoplasm and the presence of lysosomes. The outer membrane contains a polysaccharide component, but without a glycocalyx layer.

Promastigota is the presence of a clearly expressed flagella. The outer membrane contains binding molecules like glycoproteins and special cells of the immune system - manosis receptors. All this plays a big role in penetrating into the macrophage. This process is facilitated by the binding of plasma antibodies to promastigot.

Leishmania are located in the cell protoplasm of internal organs - it can be liver, kidneys, lungs, spleen, as well as cutaneous and mucous membranes, capillaries, etc. The affected cell can contain from one to two hundred leishmanias.

Life Cycle of Leishmania

Leishmania are representatives of trypanosomatid, which means their belonging to obligate parasites. The life cycle of leishmania is determined by the presence of two successive hosts: an insect and a vertebrate.

Infection of insects with leishmania occurs when they suck the blood of the carrier animal. Parasites with blood fall into the body of digestion of an insect: while in the middle intestine along the perimeter of the swallowed blood, an insect forms the so-called. Peritrophic matrix.

Promastigotnaya form of the parasite reproduces in the digestive organs of female insects. Approximately 7 days later, infectious disease reaches the upper part of the digestive system. In this case, the leishmania completely cover the digestive organ of the female. When an insect produces a bite to a mammal, its saliva, together with parasite accumulations, penetrates into the site of the bite into the skin of the new host.

As a rule, neutrophils - immune blood cells that capture parasites - tend to the site of damage. Within the cells, parasites exist until the time of natural death of neutrophils arrives. After this, leishmania is released and unhindered in the blood of a mammal.

Leishmania development cycle

Established within the human body or in the body of other mammals, leishmania can be localized in the bloodstream and in the outer covers. Mosquitoes or mosquitoes, sucking out the blood particles of a diseased animal or human, are affected by leishmania.

Already on the first day the swallowed parasite is transformed into a mobile flagellate form. It passes into the stage of reproduction and approximately in a week in the form of clusters it appears in the upper parts of the digestive tract of an insect.

With the bite of the affected insect, the active leishmania penetrate into the microscopic wound, and thence into the cellular structures of the skin, or with the blood flow to the internal organs: this depends on the type of leishmania (cutaneous or visceral leishmania).

Leishmania cutaneous - at the site of an insect bite, the reproduction of leishmanias begins and the formation of nodules (leishmaniomas), which are infiltrates containing macrophages, endothelium and lymphoid tissue cells, and fibroblasts. Subsequently, the nodes die, and in their place a ulcerative process with signs of edema and keratinization is formed: after healing, the ulcer is replaced by a scar tissue.

Leishmania visceral - in the place of an insect bite a knot is formed from which parasites with blood flow are distributed to all internal organs (spleen, lymph nodes, liver, etc.). There occurs the formation of secondary foci of infection, which leads to a proliferative change in the tissues of the organ, hyperplasia with the further development of the dystrophic and necrotic process.

Symptoms of Leishmania

Symptoms of leishmania in different geographical areas may differ, but some clinical manifestations are characteristic of all regions. Among the local population, children under 5 years of age are most vulnerable. Visitors can get sick regardless of age category.

The disease begins gradually or acutely. The most characteristic feature is a prolonged intermittent fever, accompanied by chills, fever, frequent ups and downs of temperature. The spleen and liver are enlarged and compacted. The defeat of the large intestine reveals itself in the form of diarrhea, a syndrome of impaired absorption. There is anemia and thrombocytopenia, which indicates the damage to the bone marrow. On the skin, the appearance of a characteristic rash - leishmanoids - is possible. In the future, it is possible to join purulent infection, the development of sepsis, the syndrome of increased bleeding or thrombosis, the appearance of ulcers of the oral cavity.

Leishmania visceral appears more often 3-10 months after the infection. A painful condition begins with weakness, fatigue, pain in the head and muscles. Further there are increased sweating (at night), dyspeptic disorders, signs of anemia. In childhood, the disease is more severe and can be fatal in a few months. In adult patients, the disease can last for several years.

Leishmania cutaneous can develop 1-6 months after infection. On skin integuments, a progressive node (1-1.5 cm) first appears, which later passes into the ulcerative process. Nodules can spread and also gradually pass into the stage of an ulcer. Ulcers heal extremely slowly (up to several months), after healing, scar tissue remains. In addition to the nodes, it is possible to form papules according to the type of acne.

Types of Leishmania

Identify three types of leishmania, which tend to parasitize in the human body:

• leishmania tropica - provokes the development of cutaneous leishmaniasis. This type of parasites was defined in the XIX century by the physician and scientist P. Borovsky;
• Brazilian leishmania - was first discovered in the regions of South America and provokes the development of mucous-dermal (American leishmaniasis);
• leishmania donation - affects the internal organs, provoking the development of the visceral form of the disease. In turn, donation leishmania can be subdivided into Mediterranean and Indian kala-azar, depending on the geographical location of the foci of infection.

Measures to prevent leishmania

Measures for the prevention of leishmaniasis are carried out in regions with an increased risk of the disease. Among the preventive measures are:

• early detection, isolation and therapy of patients with suspected leishmania;
• isolation and destruction (or treatment) of sick dogs, fighting with jackals, foxes, gerbils in a half-kilometer-long zone from residential buildings;
• the fight against mosquitoes (pest control);
• Use of methods of protection from mosquito attacks (nets, hats, clothes);
• vaccination (a vaccine for live Leishmania vaccines), especially for newcomers.

Leishmania is an urgent problem for the inhabitants of Asia, Africa, the Mediterranean and South America, especially for rural areas of these geographical zones.