Life Cycle of Malaria for Senior Secondary School

Text "Malaria life cycle"

The cycle starts when the female anopheline injects the malaria parasite into the human body while she is feeding on the victims blood. To do so, she injects some saliver which slows down the clothing of the human blood. As the saliver of an infected mosquito contains some forms of the malaria parasite, called sporozoites, thus the parasite is able to enter the human body. It is important to know that the malaria parasite can enter the human body only through the mosquito or rarely through a blood transfer: either in the hospital through blood donation, or from the mother to the child during pregnancy.
Once the sporozoite has entered the human blood stream. It travels through the blood vessels to the liver. In the liver it enters a liver cell and starts growing. There the malaria parasite, which is a single cell organism, divides many times within the very liver cell it has infested. After some time the liver cell ruptures under the pressure of the growing number of malaria parasites and once again the parasite enters the blood stream, in a form called the merozoite. Once the merozoites have left the liver cell, the first step of the malaria cylce which helps the malaria parasite to multiply in the human body, has been completed.

The second step takes place in the blood and the red blood cells. It starts when a merozoite infects a human blood cell by first binding to the cell and then entering it. Within the cell the malarial parasite goes through several mitotic divisions resulting in up to 32 new merozoites. Those merozoites rupture the red blood cell, resulting in a poisoning of the blood through the containments of the red blood cell and the waste products of the parasite. Whereas the released merozoites infest new red blood cells.

After a few cycles of merozoite multiplication and reinfection of red blood cells, the human body takes notice answering to the rupture of the red blood cells with high body temperature. Thus, the merozoite multiplication cycle is responsible for the typical malaria symptomes of raising and falling body temperature.

The third and last step of the malaria life cycle starts within the human body. After a few merozoite multiplication cycles the merozoites in the red blood cell start producing a different form of the parasite, the so called gametes, which are the sexual forms of the parasite a bit similar to the human sperm in the testicles and egg in the ovaries. However, the sexual forms are not able to mate in the human body because they are contained within the red blood cells.
Only if a female mosquito sucks in some infected blood and starts digesting the human red blood cells are the sexual forms of the parasite able to escape their prison and to mate. Once fertilisation has taken place the egg divides, changes form and wanders into the gut of the mosquito where it produces again through mitotic division several thousand so-called sporozoites. Those sporozoites enter the salivary gland of the mosquito which is thus able to infect a new human host on its next blood meal.

As the whole cycle of the malaria parasites takes some time within the human body as well as in the mosquito, a reinfection can be blocked by fast killing of the mosquito. The symptoms of the human host are normally treated with malarial medicaments, most of which block the multiplication of the merozoites in the red blood cell.