Figure 1. Parasite life cycle in the human host and mosquito vector.

Sporozoites that are found in a mosquito's salivary gland are injected into the skin during the blood meal. The sporozoites that reach a blood vessel travel to the liver and traverse several cells before developing in a hepatocyte. Here the parasite numbers grow significantly and they develop into a form that can invade red blood cells to initiate the cyclic asexual stage. During this time some sexual gametocytes also develop and it is this form of the parasite that is taken up by a mosquito. The parasite invades the mosquito's midgut and develops into sporozoites that can infect a new human host. Graphic prepared by Ian Moores Graphics.