The malaria parasite develops both in humans and in the female Anopheles mosquitoes. The size and genetic complexity of the parasite mean that each infection presents thousands of antigens (proteins) to the human immune system. The parasite also changes through several life stages even while in the human host, presenting different antigens at different stages of its life cycle.
Malaria parasite life cycle- a mosquito causes an infection by a bite. First, sporozoites enter the bloodstream, and migrate to the liver. They infect liver cells, where they multiply into merozoites, rupture the liver cells, and return to the bloodstream.