270 



PLASMODIUM, HAEMOPROTEUS AND LEUCOCYTOZOON 



Location : Erythrocytes. The exo- 

 erythrocytic stages are in endothelial cells. 



Morphology : The gametoc3^es and 

 schizonts are more or less round, dis- 

 placing and often expelling the host cell 

 nucleus. The pigment granules in the 

 gametocytes are coarse, often elongate 

 and rod-like. The schizonts produce 6 to 

 24 merozoites. 



Life Cycle : The life cycle of this 

 species has been studied extensively (Bray, 

 1957). It is similar to that of other avian 

 species of Plasniudiuni. Exoerythrocytic 

 stages occur in the endothelial cells. The 

 asexual cycle takes 24 hours, and syn- 

 chronicity is high. Huff (1954) listed 8 

 species of Culex, 3 each of Aedes and 



Anopheles and 1 of Psorophora which can 

 act as vectors. However, he remarked 

 that only 46% of the mosquito species 

 which had been tested were susceptible. 



Pathogenesis : P. cathemerimn 

 causes a highly fatal disease in canaries. 

 Herman and Vail (1942) reported it in a 

 canary in California, and Mathey (1955a) 

 described an outbreak in a canary breeding 

 establishment in that state in which pos- 

 sibly 165 out of 700 birds died. 



Affected canaries have subcutaneous 

 hemorrhages, anemia, splenomegaly and 

 hepatomegaly. Mathey (1955a) described 

 swelling in the region of the eyes. Hewitt 

 (1939) found splenic infarcts in 47% of his 

 experimentally infected canaries. 



Fig. 32. Avian Plasmodium and Haemoproteus in erythrocytes. A. Plasmodium gal- 



linaceum young trophozoite (ring stage). B. P. galliiiacciim older trophozoite. 

 C. P. galliiKiceuiii mature trophozoite (segmenter). D. P. gatlimicfum mac- 

 rogamete. E. P. gallinaceum microgametocyte. F. P. reliclum mature 

 trophozoite (segmenter). G. P. relictu»i macrogamete. H. Haemoproteus 

 colitmbae macrogamete. X 2800. (Original) 



BIRD MALARIA 



Diagnosis : Bird malaria can be diag- 

 nosed by finding and identifying the proto- 

 zoa in stained blood smears. If schizonts 

 or merozoites are present, it is easy to 

 differentiate Plasmodium from Haemo- 

 proteus, since these stages are not found 

 in the peripheral blood in the latter. How- 

 ever, if elongate gametocytes alone are 

 found, differentiation is usually not possible. 



Treatment : The bird malarias res- 

 pond to treatment with quinacrine, chloro- 

 quine and other antimalarial drugs. Indeed, 

 these were discovered by screening against 

 bird malarias. Chloroquine at the rate of 

 5 mg per kg, chlorguanide at 7. 5 mg per 

 kg and pyrimethamine at 0. 3 mg per kg 

 protect chickens against P. gallinaceum 

 infections. However, as a practical matter. 



