Life can exist in any form right from minutest microorganisms to huge age-old trees. For survival, organisms can depend upon so many different sources and can feed upon various things. Here we will talk about the life cycle of a plasmodium vivax which is a parasite. Also, it is a human pathogen. Plasmodium vivax is basically a protozoa. It can also be called a protozoan parasite. We will study how this protozoan begins its life and ends up in a different organism. We will see how it spreads, what are the necessities of its survival, how it grows, how many stages are there in its life cycle, it's complete life cycle.
About The Malaria Parasite
Malaria is a disease caused by a parasite called plasmodium. Plasmodium is basically a parasitic protozoan that comes from a family of apicomplexan which is of the class aconoidasida. This parasite known as plasmodium tends to attack the RBCs which are the red blood cells of any mammal like humans, reptiles, birds, etc. When we talk specifically about malaria and it's cause then Plasmodium knowlesi is that specific species of this parasite called plasmodium which causes the disease named as malaria. When a female anopheles mosquito which is infected by these parasites bites a mammal then there is the occurrence of malaria. Let's have a look at some other species of plasmodium which also are the cause of malaria:
The life cycle of this parasite is quite complex, it completes its life using mosquito or in other words, it uses mosquito as a carrier or catalyst to carry the disease and transmit it as well.
This malaria parasite called plasmodium completes its life cycle in three stages namely Gametocytes which is the first stage then sporozoites which is the second stage and lastly merozoites which is the third and final stage. It has a very complex life cycle. We are going to study it in detail.
Stages In The Life Cycle Of Plasmodium
There are three stages in the life cycle of a plasmodium
The first stage is called as gametocytes
Gametocyte is the first stage in the life cycle of plasmodium.
The female gametocyte is called macrogametocytes while male gametocyte is called microgametocyte. These macrogametocyte and microgametocyte undergo fertilization inside the anopheles mosquito. The mating of gametocytes inside the anopheles mosquito later develops into a sporozoite. It takes around 15-18 days for the formation of a sporozoite. Sporozoite is the parasite.
Sporozoite is stage two in the life cycle of plasmodium.
An anopheles mosquito which is infected by the sporozoite when bites a human there's transmission of sporozoites from the mosquito into the bloodstream of humans. After sporozoites have entered the bloodstream they tend to enter into the liver cells of humans. Sporozoites enter the liver cell and here they grow into schizonts as they multiply asexually. These rupture the liver cells in order to release merozoites.
Merozoites from the liver cells are released into the vesicles. From the heart, these merozoites travel to the lungs and settle themselves in the lung capillaries. The disintegration of vesicles occurs and merozoites enter the blood phase which is a phase in their development.
While traveling in the bloodstream merozoites tend to attack the red blood cells also called the erythrocytes. They keep on multiplying in the red blood cell till the cell bursts.
When an infected human is bitten by a mosquito, there is ingestion of gametocytes by the mosquito and later these gametocytes develop into mature gametes.
The female gamete which is fertilized develops into ookinetes which further develop into oocysts and settle onto the outer or the exterior surface.
Thousands of active sporozoites develop inside this oocyst. Eventually, the oocyst bursts resulting in the release of sporozoites that travel to the salivary gland of the mosquito when they bite an infected human.
And this way once again the cycle of infection of humans through malaria begins when the infected mosquito bites another person.
And this way the cycle of plasmodium completes in two organisms.
Plasmodium Life Cycle Diagram
[Image to be added Soon]
Through this diagram representing the entire life cycle of the plasmodium, we can easily understand how this parasite completes it's life using two organisms. In the figure above we can easily distinguish the life cycle of plasmodium in a human and life cycle of plasmodium in a mosquito.
Q1: Describe the Life Cycle of Plasmodium.
Answer- Plasmodium has a complex life cycle which can be distinguished into three stages, explained below:-
Stage 1: Gametocytes
During a blood meal, the male and female gametocytes are transmitted through an anopheles. In the gut of the mosquito, male and female gametocytes mate, and after a period of 15 to 18 days, a parasite called sporozoite is formed.
Stage 2: Sporozoites
The sporozoite formed are then transmitted through the saliva into the bloodstream, provided if an infected mosquito feeds on a human. Through the bloodstream, these sporozoites lead into the liver where they mature into schizonts.
Stage 3: Schizonts
Over a passage of one to two weeks, the schizonts multiply to form several other forms known as merozoites. The merozoites then enter the bloodstream again in order to attack the red blood cells. The merozoites destroy all blood cells during the process of growing and multiplying. A certain part of theses merozoites develops into gametocytes which are later ingested into the blood by a mosquito, giving birth to the whole cycle all over again.
Q2: How is Malaria Caused?
Answer- Malaria is a life-threatening disease and can be transmitted through the bite of an infected anopheles mosquito. These infected mosquitoes carry the parasite plasmodium which is released in the human bloodstream, provided the infected mosquito bites the human. Broadly, there are four kinds of malaria parasite that have the tendency to infect humans, listed below:-
Plasmodium falciparum causes a more severe form of the disease and those infected by this to have a higher risk of death. If a mother is infected with malaria at the time of birth, the disease can be passed to the baby as well which is why this is known as congenital malaria.