Plasmodium is a protozoan parasite that causes malaria in humans. The life cycle of Plasmodium involves complex interactions between its vector (usually female Anopheles mosquitoes) and a human host. There are several species of Plasmodium that can infect humans, with Plasmodium falciparum and Plasmodium vivax being the most common. Here is a detailed descriptio of the life cycle of Plasmodium:
Life cycle of Plasmodium
1.Merogony (Liver Phase):
-It is first step of life cycle of Plasmodium, which begins from the human host. When an infected mosquito bites a human, the sporozoites, that are present in mosquito’s saliva, are injected into the human bloodstream.
- The sporozoites quickly travel to the liver, where they invade hepatocytes (liver cells). Inside the hepatocytes, each sporozoite develops into thousands of merozoites through a process called merogony.
- The hepatocytes rupture, releasing the merozoites into the bloodstream. This phase is asymptomatic, as the parasites are still in the liver and haven't yet caused symptoms of malaria.
2. Erythrocytic (Blood) Cycle:
- The released merozoites enter the red blood cells (erythrocytes) and initiate the erythrocytic cycle.
- Inside the red blood cells, the merozoites undergo asexual reproduction, leading to the formation of new merozoites. This process is known as schizogony.
- The red blood cells eventually rupture, releasing the new merozoites into the bloodstream. This rupture is responsible for the cyclical fever and other symptoms associated with malaria.
3. Gametogony (Sexual Stage):
- Some merozoites differentiate into male and female gametocytes, which can be taken up by a feeding mosquito during a blood meal, completing the cycle.
- If a mosquito ingests gametocytes, they will undergo sexual reproduction in the mosquito's midgut, restarting the sporogony phase.
The symptoms of malaria in humans are primarily associated with the erythrocytic cycle when the red blood cells rupture, releasing merozoites and causing fever, chills, and other clinical manifestations. The complete life cycle, involving both the mosquito and human host, is necessary for the perpetuation and transmission of the Plasmodium parasite.
4. Sporogony (Mosquito Phase):
- When a female Anopheles mosquito takes a blood meal from a infected person, the gametocytes of the Plasmodium enters into the mosquito.
- When plasmodium reach to the mosquito's midgut, the male and female gametocytes undergo sexual reproduction, forming zygotes. The zygotes develop into motile ookinetes, which penetrate the mosquito midgut wall.
- The ookinetes transform into oocysts, which undergo further development and produce thousands of sporozoites.
- When the oocysts rupture, sporozoites are released into the mosquito’s hemocoel (body cavity). These sporozoites migrate to the mossquito’s salivary glands, where they can be transmitted to a new human host during the mosquito’s next blood meal and repeat the cycle.