Plasmodium malariae it is one of the four species of parasites associated with the human disease known as malaria or malaria, endemic in tropical and subtropical latitudes, where the multiplication of its vector insect is feasible.
Malaria or malaria is a parasitic disease that affects humans and is potentially lethal. It is caused by infection with one of four species of parasites of the genus Plasmodium: P. falciparum, P. vivax, P. ovale Y P. malariae.
Of these four species, P. falciparum Y P. vivax are by far the most dangerous. P. falciparum, By 2017, it was the species causing more than 99% of cases in Africa and more than 62% of cases in Asia, while P. vivax caused more than 74% of the cases in the American continent.
For 2018 it was estimated that there were almost 230 million people affected by this disease in the world, with an average number of deaths for that same year of around 400 thousand, of which more than 60% corresponded to children under 5 years of age..
The life cycle of these parasites comprises an insect vector (mosquitoes Anopheles) and a host mammal (essentially human), among which several vital stages are distinguished.
The clinical diagnosis is made, among many things, by detecting the parasites in the blood and their treatment can prevent mortality and alleviate the symptoms of the pathology. It is a disease that has a cure when it is diagnosed early.
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Plasmodium malariae is a species of parasite belonging to the group of apicomplexes, which are a group of unicellular microorganisms characterized by being endoparasites of many animals.
Apicomplexes are classified in this way thanks to the presence of a so-called "apical complex" and a type of plastid known as the "apicoplast" (essential for metabolism). This apical complex is a type of adaptation that allows these parasites to penetrate the cells of their hosts..
Like the rest of the members of this group, Plasmodium malariae it is a spore-forming unicellular parasite and obligate endoparasite of animal species. It feeds on the hemoglobin within the red blood cells of its hosts and produces a pigment known as hemozoin..
Other of its characteristics are:
- It has 14 chromosomes, almost always in a single copy
- Like all eukaryotes, it has a nucleus, mitochondria, a Golgi complex, and an endoplasmic reticulum.
- They have specialized secretory organelles known as roptria that are club-shaped and are involved in invasion of host cells and their internal modification.
- They also have intracellular structures called micronemes, which contain proteins required for motility, recognition and adhesion to host cells.
- They have a parasitophorous vacuole, which is a kind of extension of the plasma membrane that covers the parasite inside the host's cells and protects it against degradation by phagolysosomes.
This parasite also has a wide distribution, since it is not only present in South America but also in the Asian and African continents, although it is less frequent than its close relative Plasmodium falciparum.
The morphology of the parasite depends considerably on the stage of the life cycle in question, which is why we will describe below those that are most prominent and those that are used for the clinical parasitological diagnosis..
This is the form that develops inside human erythrocytes (red blood cells) and is characterized by its "ringed" appearance. They are cells with a fairly "robust" cytoplasm and a nucleus that is seen as a large chromatin point.
The mature trophozoites of Plasmodium malariae they have a fairly compact cytoplasm and also have a large chromatin point in the nucleus. On some occasions forms with "bands" or "baskets" and with large dark brown pigments can be found..
The schizonts of Plasmodium malariae they are "structures" that comprise 6 to 12 merozoites inside. These cells have prominent nuclei and also have thick dark brown pigment. They can be arranged inside the schizonts in the form of a rosette.
These cells tend to be round or oval and have scattered granules of brown pigments in the cytoplasm. They are characterized by "filling" the erythrocytes that infect.
P. malariae It is a eukaryotic parasite belonging to the phylum of the apicomplexes (Apicomplexa) and its taxonomic classification, according to different sources, is the following:
- Super kingdom: Eukaryota
- Kingdom: Protista
- Subkingdom: Protozoa
- Edge: Apicomplexa
- Class: Aconoidasida
- Order: Haemosporida
- Family: Plasmodiidae
- Gender: Plasmodium
- Subgenre: Plasmodium
- Species: Plasmodium malariae
Plasmodium malariae has a digenetic life cycle, that is, the parasite requires two hosts to complete its cycle: an invertebrate vector, such as a mosquito of the genus Anopheles and a host mammal, such as a primate of the genus Homo.
Like his close relatives Plasmodium falciparum, Plasmodium vivax Y Plasmodium or voucher, Plasmodium malariae It has different life forms throughout the cycle, which are known as: sporozoite, schizont, merozoite, trophozoite, gametocytes (macro and microgametocyte), ookinet and oocyst.
Likewise, like the aforementioned species, Plasmodium malariae is transmitted to its definitive host (almost always a human) when a female mosquito Anopheles infected feeds on a person's blood and inoculates the sporozoite form of the parasite.
Sporozoites "injected" by the mosquito can reach liver cells (in the liver) and infect them; as they mature, these become schizont, which break the cells and are released as merozoites.
This replication in the liver is called the exo-erythrocytic schizogony phase and precedes the erythrocytic phase, where the merozoites produced in the liver are directed..
The erythrocytic schizogony phase of the parasite involves its asexual multiplication within erythrocytes, which are the blood cells that carry oxygen to the tissues..
To achieve this, merozoites derived from the exo-erythrocytic phase infect red blood cells, where they become ringed state trophozoites..
These trophozoites can later mature into the schizont form and their multiplication is such that they disrupt the erythrocytes and are released as merozoites. Parasites at this stage are responsible for the clinical manifestations of the disease.
Some of the forms of the parasite that infect red blood cells can be differentiated into what experts know as the "erythrocytic sexual phases" or male (microgametocyte) and female (macrogametocyte) gametocytes. A gametocyte is a gamete precursor cell. This occurs even inside erythrocytes.
A mosquito Anopheles it can feed on the blood of an infected host and ingest erythrocytes containing gametocytes. The multiplication phase of the parasite in the insect vector is known as the sporogonic cycle.
Inside the stomach of the mosquito, the microgametes formed by the microgametocyte penetrate the macrogametes derived from the macrogametocyte, forming multiple zygotes. These cells differentiate into elongated, mobile shapes known as ookinets..
The ookinets can invade the cells of the wall of the mosquito's midgut and there transform into oocysts. These forms of the parasite grow and break the cells that contain them, releasing another stage called the sporozoite, capable of making its way to the salivary glands of the insect..
This is the infective phase and it is the one that the mosquito can inoculate mammalian hosts when feeding on their blood, thus perpetuating the life cycle of the parasite..
Plasmodium malariae produces, like the other three species mentioned above, a clinical condition in humans called malaria or malaria. However, there are reports that also suggest that it can harbor canines, causing the same disease.
It is a potentially lethal disease that affects thousands of people in the world, especially in less developed countries, with poor sanitary conditions and where prevention campaigns are not promoted..
Malaria is a disease characterized by producing acute fever. After being "bitten" by an infected vector, symptoms can appear within the first 10 or 15 days in a healthy, non-immunized individual (who did not have the same disease before).
The main symptoms are not very different from those of some colds or temporary illnesses: fever, headache, chills, weakness, vomiting, diarrhea, etc. However, children, for example, may have severe anemia and respiratory or brain conditions.
These symptoms vary somewhat depending on the species and have been shown to be among the most common clinical complications when it comes to Plasmodium malariae there is nephrotic syndrome, which involves excessive excretion of protein in the urine.
It is also important to note that there are cases of asymptomatic infections in those regions where the disease is endemic, that is, Sub-Saharan Africa, South-East Asia and America..
Although these are the typical symptoms of malaria or malaria, it should be noted that those produced by Plasmodium malariae are not as severe as those that produce Plasmodium falciparum Y Plasmodium vivax.
Although the parts of the world most affected by the disease caused by the aforementioned group of parasites are those where the vectors can reproduce and spread more easily, there are some prevention methods that can be taken into account to avoid contagion.
Since contagion depends exclusively on contact with the vector mosquito, the World Health Organization suggests:
- Use of insecticide-treated nets
- Application of mosquito nets in the domestic area, especially in the rooms where you sleep
- Residual insecticide spraying
- Elimination of possible sources of mosquito multiplication
- Ingestion of “antimalarial” drugs as prevention for travelers and pregnant women
On the other hand, there is treatment to attack the disease in its earliest stages, which is very useful when the diagnosis is made in time, since mortality is reduced and transmission is prevented..
The most widely used drug treatment against malaria, and the one that has been shown to be most effective especially against P. falciparum, which is the most “aggressive” species, is artemisinin, also called qinghaosu.
Vaccines have also been developed, but these offer only partial protection in young children.
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