Plasmodium

Plasmodium, commonly known as the malaria parasite, is a large genus of parasitic protozoa. There are about 200 species. Infection with these protozoans is called malaria, a deadly disease widespread in the tropics. The parasite always has two hosts in its life cycle: a mosquito vector and a vertebrate host.
The life-cycle is very complex. There is a sequence of different stages in the vector and the host. These stages include: 
The genus "Plasmodium" was first described in 1885. At least ten species infect humans. Other species infect other animals, including birds, reptiles and rodents, while 29 species infect non-human primates. The Apicomplexa – the phylum to which "Plasmodium" belongs – are thought to have originated within the Dinoflagellates – a large group of photosynthetic protozoa.
The most common forms of human malaria are caused by "Plasmodium falciparum", "Plasmodium vivax", "Plasmodium ovale", and "Plasmodium malariae". "P. falciparum" malaria, common in sub-Saharan Africa, is especially dangerous.