It is a parasite, and the most common cause of malaria in birds.

[3] Like all Plasmodium species, P. relictum has both vertebrate and insect hosts.

The vertebrate hosts for this parasite are birds.

[2] Climate change is broadening its distribution further and is expected to continue to do so, including into higher elevations.

Infections in numerous wild birds and experimental animals have been described including partridges, canaries, chickens, ducks, pigeons[2] and Spheniscus magellanicus (Magellanic penguins).