a genus of parasitic protozoans of the suborder Hemosporidia, order Coccidia. There are approximately 50 species, widely distributed. Asexual reproduction of Haemoproteus (schizogony) occurs in the endothelium of blood vessels (predominantly in the lungs) in birds and also in reptiles—lizards, tortoises, and snakes. Gametocytes enter the erythrocytes. The sexual process and sporogony occur in blood-sucking dipterous insects, which serve as the carriers of Haemoproteus and which, upon attacking vertebrate animals, infect them. Haemoproteus causes serious disease in chicks. No pathogenic effect is observed in adult fowl.