Plasmodium Life Cycle

Introduction:

Plasmodium is a genus of parasitic protozoans that fall under the family Apicomplexa, the class Aconoidasida and the sporozoan subclass Coccidia. Plasmodium is known to infect the red blood cells in mammals like humans, birds, reptiles and so on. P. knowlesi is the species of plasmodium that causes the infectious disease known as Malaria. Malaria occurs when the infected female Anopheles mosquito bites human beings or any other mammal. Some other species of plasmodium known to spread Malaria are P. vivax, P. ovale, P. malariae, and P. knowlesi. The plasmodium parasite displays a complex life cycle as it uses an insect (mosquito) as a catalyst to carry and transmit the disease.

Let’s look at the life cycle of a plasmodium to get a better understanding.

Life Cycle of Plasmodium:

Plasmodium parasites have a complex life cycle that includes three stages namely Gametocytes, Sporozoites and Merozoites.

1) Gametocytes – Stage 1 –

The male gametocytes called microgametocytes and female gametocytes called macrogametocytes are transmitted through an anopheles mosquito during a blood meal. The gametocytes within the mosquito develop into a sporozoite. The male and female gametocytes mate inside the gut of the mosquito, and after 15 to 18 days, they form a parasite called sporozoite.

2) Sporozoites – Stage 2 –

When the infected mosquito feeds on humans, the sporozoites are transmitted through the saliva into the bloodstream. After that, the sporozoites enter the liver cells and here they mature into schizonts. Later, these sporozoites rupture and release merozoites.

3) Merozoites – Stage 3 –

Over the next one or two weeks, each schizont multiplies in order to form several other forms known as merozoites. The merozoites exit from the lever, entering the bloodstream again and here they attack the red blood cells. The merozoites grow and multiply more while destroying all blood cells in that process. Certain merozoites develop into gametocytes, which is later ingested into the bloodstream by a mosquito and the whole cycle starts again. When the red blood cells are destroyed by the merozoites, it releases a toxin that causes bone-shaking chills and fever. Extreme cold chills and fever are classic symptoms of malaria in human beings.

Conclusion:

The evolution of plasmodium evolved in parallel with the vertebrate evolution for the past 120 million years. Therefore, the plasmodium has gone through new hosts, which is followed by adaptation to those hosts, which shows the primary reason for the evolution of the plasmodium. Several species of plasmodium have been isolated from the chimpanzees that include, P. gaboni, P. falciparum, P. ovale and P. reichenowi. The other species are isolated from gorillas. Plasmodium parasites found in reptiles are P. mexicanum and P. floridense and plasmodium in birds include P. relictum and P. juxtanucleare.

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