Haemosporidia

HAEMOSPORIDIA, haemosporidia, coloring sporozoans, a group of coccidiomorphous sporozoans (Sporozoa coccidiomorpha), established by Danilevsky. Found in all vertebrates from mammals to fish. All H. parasitize in the blood, mainly in erythrocytes. Some H. (Leucocytozoon) parasitize in leukocytes. Other H., while being parasites of erythrocytes, spend part of their cycle in endothelial cells. They reproduce through phenomena of alternation of sexual and asexual generations and hosts, with the asexual cycle occurring mostly in the intermediate host, a vertebrate, and the sexual cycle in an invertebrate (an insect), which thus serves as the final host. Most H., living in erythrocytes, destroy them, forming characteristic pigment deposits (so-called melanin). H. include three main families: 1. Plasmodidae - parasitize exclusively in erythrocytes of vertebrates (found in mammals, birds, and reptiles). Various species of the genus Plasmodium are the causative agents of malaria in humans, monkeys, and birds. The final hosts and vectors are various mosquitoes. 2. Haemoproteidae - parasitize in erythrocytes and in endothelium exclusively in birds. They form pigment. The final host and vector are flies of the genus Lynchia and others (see Haemoproteidae). 3. Leucocytozoidae - parasitize in leukocytes of various birds. They do not form pigment. The vector is a two-winged insect, Ornithomyia.