The main host of the malarial plasmodium. Life cycle, structure, multiplication of parasite
Despite the development of medicine, one of the mostwidespread diseases and in modern times remains malaria. Although there are now drugs for its successful treatment, but annually it takes the lives of almost two million people. Malaria refers to protozoal diseases and is caused by a small parasite - malarial plasmodium. He has a complex development cycle, and he can exist only in the body of the carrier. Therefore, you can catch malaria when you bite a mosquito. This is the main owner of the malarial plasmodium. And man is his intermediate master.
What is a malarious plasmodium
The causative agent is a unicellular organism. It belongs to the sub-archeology of the protozoan, the plasmodial group. Only four species from a huge number of these microorganisms parasitize the human body and cause malaria. This parasite is also referred to as the suborder of blood sporovikov, as it multiplies in blood cells, feeds on hemoglobin and is transmitted with blood.
Types and structure of parasites
Only four types of malarial plasmodia causedisease in humans. The structure and life cycle they have the same, the differences only in the ways of manifestation of the disease. In accordance with this they are named:
- causative agent of tropical malaria;
- causative agent of a three-day malaria;
- the causative agent of a four-day malaria;
- causative agent of oval malaria.
What is a malarial plasmodium? The structure of this microorganism is different at different stages of development. It enters the human body plasmodia in the form of a sporozoid - a thin vermicular unicellular organism with a length of only 5-8 μm. After introduction into erythrocytes, it takes the form of an amoeba, grows and destroys blood cells. The parasite can also exist as gametocyte gametes, and in the mosquito they merge into a sporocyst.
Life cycle of malarial plasmodia
It is a complex process. During the evolution of the parasite has adapted to live only in the body of other organisms, choosing for this two hosts: a mosquito and a human. Therefore, malaria infection occurs mainly through an insect bite or directly through the blood. It is believed that the final owner of a malarial plasmodium is a person. After all, it manifests itself in the symptoms of the disease, and the mosquito does not even notice that it is the carrier. But in fact, it is in the insect organism that the parasite reproduces sexually. Therefore, scientists have proved that a person is an intermediate host of a malarial plasmodium. What is the development cycle of the parasite?
1. When sucking infected blood into the body of a mosquito, immature sex plasmodium cells enter. It is there that they become fertilized and, attaching themselves to the stomach of a mosquito, begin to share. The total number of sporozoids of the parasite can reach hundreds of thousands, more of them are in the salivary glands of the mosquito. That is why an insect is the main owner of a malarial plasmodium.
2. When you bite a mosquito, sporozoids get into the blood of a person. There the parasite passes through two phases of development. It is divided in the liver, forming merozoites, and then penetrates into the red blood cells, where it undergoes asexual reproduction.
The main host of malarial plasmodia
The carrier of the disease is the female mosquitoone species - living in a hot climate. This is due to the fact that the development of malarial plasmodium is possible only at temperatures above 16 degrees. And most actively this process is at 25-28 degrees. Sex plaemodia cells found in the mosquito can only be fertilized there. Within 10-15 minutes a zygote is formed, which turns into a sporocyst and is attached to the outer wall of the insect stomach. There she begins to share. In one sporocyst, several thousand sporozoids are formed. And there are a lot of such fertilized cells in the mosquito's body.
Life of a parasite in the human body
When a mosquito bites, which is the carriermicroorganism, malarial plasmodium enters the human blood. The parasite in the body passes through two phases of development: tissue and erythrocyte. It is in the second stage of plasmodium and causes the symptoms of malaria.
1. The first phase is called tissue schizogony. Penetrating into the liver cells, the sporozoid begins to divide, forming up to 50 thousand merozoites. They go to the blood, penetrating into the red blood cells. This stage does not cause any symptoms and lasts from 5 to 16 days. In some cases, for example, when infected with plasmodium trednevnoy malaria, part of the sporozoids remain in the liver in hibernation, six months later causing a relapse of the disease.
2. When the plasmodium leaves the liver in the blood, it penetrates into the red blood cells, and the cyclic process of erythrocytic schizogony begins. Feeding on hemoglobin, the merozoites develop and divide, forming new cells: asexual schizonts and sex - gametocytes. By destroying the erythrocyte, they exit into the blood plasma. At this moment, a person has a fever attack. When gametocytes form in the blood of a person, it becomes a source of infection, and when a mosquito stings the plasmodium penetrates into the insect's body and begins sexual reproduction there.
Development of a parasite in human blood
Why is it so dangerous for a person malariousplasmodia? Reproduction of it in human blood leads to the destruction of red blood cells. In these blood cells, the parasite undergoes a number of changes: the merozoites pass to the stage of the trophozoid, which is fed by hemoglobin and rapidly grows, then schizonts are formed. They reproduce asexually and destroy the red blood cell. At the same time, foreign proteins, potassium salts, remains of destroyed blood cells and metabolic products of the parasite enter the blood.
Features of malaria
This disease, called "marshfever ", is known from ancient times.It was spread in all tropical countries only in the 17th century the disease was successfully treated with the help of the cinchona bark, and at the end of the 19th century the malignant pathogen was discovered, and only in the middle of the 20th century was the life the cycle of the malarial plasmodium, effective medications have been developed to treat the disease.In spite of this, more than 300 million people are ill with malaria every year in hot countries.Also two million cases are fatal. Evan is characterized by four stages:
- The incubation period, in which there is weakness, a headache.
- The second stage, feverish. It begins with a strong chill. At this time, the pulse increases, the pressure rises, and the patient can not warm up. After 1-3 hours, the temperature rises to 41 degrees, nausea, convulsions and headache occur. After that, the temperature drops, which is accompanied by a strong perspiration.
- After 10-12 attacks, the infection fades and a secondary latent period is observed.
- If the treatment was wrong, then throughFor several months, the disease recurs. It can also arise in the case of infection with one of the plasmodium species that causes tropical malaria. Part of the sporozoids of this parasite remain in the human liver in a dormant state.
What is the danger of the disease?
In addition to recurring periods of fever, malariacauses disruption of the work of all human systems and organs. Can develop myocardial dystrophy, neuritis, migraine, nephritis, thrombocytopenia and anemia. Liver and kidneys are severely affected. In some cases, the disease occurs in a chronic form and is difficult to treat. Children are especially vulnerable to infection - the mortality among them is quite high. Until now, the disease is very common in Africa, Australia, South America, the Red and Mediterranean seas, Southeast Asia and India.
Treatment and prevention of malaria
Even in modern society can not copewith this disease. After all, the main owner of a malarial plasmodium is a mosquito. And in tropical countries, especially with a humid climate, these insects are very numerous. Therefore, the most important thing in the prevention of disease is to protect oneself from insect bites. To do this, you can use mosquito nets or repellents. To treat the disease in the event of infection, many drugs are currently used: Chlorozine, Mefloquine, Primachin, Akrihin and Quinine, which has been known since the 19th century, not only quickly relieve the symptoms of a beginning attack, but also completely destroy the parasite. People living in a tropical area and having a disease acquire immunity to this type of pathogen, but they can be carriers of infection, and those who are going to go to such countries are advised to constantly take antimalarial drugs.
