The parasite completes a part of its life histroy in man in two stages.

They are : a) Pre-Erythrocytic cycle. b) Erythrocytic cycle.
1. When an infected female Anopheles mosquito bites, the parasite enters our blood.
At this point of time the parasite is in a stage of its life history called sporozoit.
2. The sporozoits spend about 30 minutes in blood and enter the liver cells. They feed on the contents of liver cell and fill the entire cell. This stage is called crypto-schizont stage.
3. Schizonts reproduce asexually to produce daughter cells called crypto- merozoits.
The liver cell ruptures and merozoits are released into blood.
4. As these changes occur in the liver cells, this stage is called Pre-Erythrocytic cycle. This phase of the life cycle is for 7 to 17 days. This cycle ends when the parasite enters the red blood cell.
5. In the red blood cell, the parasite feeds on the contents of red blood cell and grows in size. They are called schizonts.
6. The schizonts divide repeatedly and produce 6 to 2 merozoits. The red blood cell reuptures and releases the merozoits into the blood. The merozoits again attack new red blood cells and produce more number of merozoits. This phase of the cycle is called Erythrocytic cycle.
7. The rupture of the red blood cell and release of the parasite into the blood is associated with chills and fever known as malarial fever.