Malarial plasmodium: life cycle, developmental and organizational features

Everyone has probably heard about such a dangerous disease as malaria. But not everyone knows that its causative agent is the simplest microscopic animal - the malarial plasmodium. About the life cycle, features of the structure and development of this organism you will learn from our article.

Features of the organization The simplest

Plasmodium is the representative of the most primitive group of animals - the single-celled or protozoan sub-kingdoms. They are characterized by the following features:

• body consists of a single cell that performs the functions of the whole organism;
• kernel;
• lack of a dense cell wall;
• movement with the help of specialized structures: cilia, pseudopods, flagella;
• presence of digestive and contractile vacuoles;
• gas exchange through the cell surface;
• sexual and asexual reproduction.

Parasitic Unicellular

Protozoa have mastered many habitats: soil, fresh and salt water bodies, swamps. Among them there is also a group of parasitic unicellular. They develop in various organs of animals and humans, while causing serious diseases.

One of them is the malarial plasmodium. The dimensions of this parasite are microscopic. Depending on the species, the plasmodial cell may have the form of a ball, an elongated strand or a ring. In total, they number about 180. But 10 species are parasitic in the human body, 5 of them are the most dangerous.

History of the disease

The malarial plasmodium, whose life cycle we are considering, causes a serious infectious disease. Translated from the Italian language, its name means "bad air".For a long time it was called a swamp fever.

Scientists suggest that the first cases of malaria were known 50,000 years ago in Central and West Africa. Evolutionary studies led to the conclusion that the ancestor of the modern species was at first free-living. Over time, he adapted to the habitation in the intestines of invertebrates, and then the first bloodsucking.

The cause of this fatal disease for a long time was unknown. Only at the end of the XIX century the French doctor Charles Laveran, who practiced in Algeria, discovered in the red blood cells of the patient unknown cells. For this discovery, he was awarded the Nobel Prize.

The cycle of the malarial plasmodium: the

scheme Like all representatives of the Spore type, this parasite has a complex life cycle. It flows with the change of hosts: intermediate and final. In the body of the first parasite reproduces asexually. The cycle of development of a malarial plasmodium in the body of the final host continues. There occurs sexual reproduction of a parasitic animal.

During its development, the malarial plasmodium passes through the following stages:

• Human liver cells.
• Erythrocytes.
• Blood of a mosquito.

Further, through the bite, the parasite again enters the human body and the cycle repeats.

Asexual reproduction of

The intermediate host of the parasite is a human. It is in his body that plasmodium reproduces asexually. This happens by dividing the cells in two.

How does this organism get into human blood? This occurs when a mosquito is bitten by a malarious plasmodium. The stages of its development that occur in the body of the intermediate host can be divided into several stages.

First plasmodium with blood flow enters the human liver cells. Here it multiplies in the manner of schizogony. In the course of this process, the nucleus is repeatedly divided, a cytoplasm around each of the parts formed forms. After this, newly formed cells divide again.

After several such divisions, the parasite cells enter the bloodstream. Their development occurs in erythrocytes. Plasmodium continues to divide many times, while destroying blood cells. Their defeat occurs quickly enough - a maximum of 72 hours.

When the erythrocytes are destroyed, the toxic products of the plasmodium live in the blood. They cause a person fever. As a result of several successive divisions, precursors of the germ cells are formed from the parasite cells, which are called gametocytes.

Ultimate host

The cycle of development of malarial plasmodium continues in the body of a mosquito. It becomes infected with a parasite when bitten by people with malaria. The mosquito is the ultimate host, since dangerous cells reproduce sexually in it.

When bitten by gametocytes from erythrocytes penetrate into the blood of a mosquito. Here they become full-fledged sex cells. The process of fertilization takes place in the intestine of the insect. As a result, numerous mobile cells of the parasite are formed.

Further, the life cycle of the malarial plasmodium is repeated. Its cells accumulate in the salivary glands of the mosquito, and when bitten again fall into the bloodstream of a person.

Dangerous symptoms of

Genus Malarial mosquitoes number more than 400 species. Do not think that their representatives live only in African countries. They are common everywhere except in the northern regions. Characteristic features of adult insects is an elongated body, long legs and proboscis, a short head. Their wings along the veins are covered with scales.

The bite of such a mosquito is the most common way of contracting malaria. But the cause can also be non-sterile medical instruments. The first symptom of the disease is the appearance of fever. As the erythrocyte is destroyed, there is an increase in the size of the spleen, compaction of the liver, development of anemia.

So, for the life cycle of malarial plasmodia is characterized by a change of hosts: intermediate and final. The first person is. In the cells of his blood, asexual reproduction of the plasmodium occurs by schizogony. The final host of the parasite is a mosquito. In his body, the cells of the parasite reproduce sexually. The development of malaria occurs only if it is possible to repeat the stages of the life cycle. Otherwise, a dangerous disease does not develop.