Plasmodium Circumflexum

Hosts: This species is quite common in a wide variety of hosts. The type host is a German thrush, Turdus pilaris. It was found in the ruffed grouse in Canada by Fallis (1945, 1946), and a similar form was found in the Canada goose in Illinois by Levine and Hanson (1953).

Location: Erythrocytes. The exo-erythrocytic stages are in endothelial cells.

Morphology: The gametocytes and trophozoites are elongate; they tend to encircle the host cell nucleus but are generally not in contact with it and do not displace it. The schizonts produce 13 to 30 merozoites (average 19).

Life Cycle: The life cycle is similar to that of other avian species of Plasmodium. Exoerythrocytic stages occur in the endothelial cells. The known vector mosquitoes are Culex tarsalis, Culiseta annulata and C. melaneura. Two other species of Culex and 5 of Aedes have been found insusceptible (Huff, 1954).