Text: Today there are over 200 species of Plasmodium that cause malaria or malaria-like illnesses in man and a wide range of animals. However, only five of the Plasmodium species can infect humans, and these five species do not seem to infect other species, which have their own illnesses due to other Plasmodium species. Nevertheless, there is speculation that the human form of malaria originated in chickens and then evolved into forms that could infect humans and chimpanzees. Consequently, malaria today is acquired via the Anopheles mosquito, which transmits the Plasmodium from human to human. Nevertheless, the ancient origins of Plasmodium were probably zoonotic.