The malarial parasite (Plasmodium) undergoes its life cycle in two different host organisms - female Anopheles mosquito and human. The sexual stage of its life cycle occurs in the female Anopheles mosquito, and asexual stage occurs in the human body. When a female Anopheles mosquito bites a healthy person, the malarial parasite (in its infective sporozoite stage) is injected into his blood.
The sporozoites are present in the salivary glands of the mosquito, enter the blood of the human and travel to the liver. In the liver, the sporozoites multiply asexually and form schizonts. These schizonts infect the RBC and multiply further to form the merozoites. The merozoites give rise to the male and female gametocytes. When a female Anopheles mosquito bites this individual, it takes up the gametocytes with the blood. In the stomach of the mosquito, the fertilization of these gametes occurs.
The mature infective stages called sporozoites then develop and migrate to the salivary glands of the mosquito. When this mosquito bites a healthy human again, the sporozoites are introduced into the human body, and the cycle continues.
