Plasmodium relictum is a parasite, and the cause for the malaria in birds, it is a widespread parasite infecting more than 300 species of birds; a blood-feeding insect host is the first part of the life cycle of Plasmodium species; the insect will inject parasites into a vertebrate host during a blood feed. The Parasites will grow in the vertebrate body tissue first then they will enter the bloodstream in order to infect the red blood cells. Malaria is the result of the destruction of the blood cells of the host. Parasites first infect the liver in which they can stay for a year replicating themselves before infecting  the erythrocytes. Then the parasites will go through continuous cycles of  blood infection, while a small amount of parasites go into a sexual stage called differentiate gametocyte. The Common chiffchaff (Phylloscopus collybita} is a natural host of the Plasmodium relictum as the Galapagos penguin as well, so the parasite has a Symbiotic relationship with these species causing mortality to the host.