CBSE · Class 12 · Biology · Human Health and DiseasesDescribe the life cycle of Plasmodium in the human host, starting from the entry of the parasite to the appearance of fever symptoms.

The life cycle of Plasmodium in the human host occurs as follows:

1. Entry: Plasmodium enters the human body as infective sporozoites through the bite of an infected female Anopheles mosquito.
2. Hepatic Phase: The parasites reach the liver cells (hepatocytes) via blood circulation and multiply asexually inside liver cells, eventually bursting the liver cells and releasing parasites into the bloodstream.
3. Erythrocytic Phase: Parasites attack red blood cells (RBCs) and multiply asexually, causing RBCs to rupture.
4. Release of Haemozoin: Rupture of RBCs releases a toxic substance called haemozoin, which is responsible for the recurring chills and high fever felt every 3 to 4 days.
5. Gametocyte Formation: Parasites develop into sexual stages called gametocytes (male and female) inside RBCs, which are later taken up by female Anopheles mosquitoes during a blood meal to complete the sexual cycle.