Malaria parasite life-cycle in red blood cells, illustration. In humans malaria is caused by infection with Plasmodium sp. parasites, which are transmitted by the bite of female Anopheles sp. mosquitoes. Across top the merozoite stage of the parasite (blue) is attaching to and entering a red blood cell. Across bottom the parasite develops a vacuole within which it reproduces. The new merozoites are released from the cell and go on to invade other red blood cells.