268 



PLASMODIUM, HAEMOPROTEUS AND LEUCOCYTOZOON 



or irregular, relatively small, and usually 

 in contact with the red cell nucleus. The 

 schizonts produce 3 to 7 (usually 4) mero- 

 zoites. The host cell is often distorted. 



Life Cycle : The life cycle has not 

 been completely studied. According to 

 Beltran (1943), schizogony takes about 24 

 hours and its synchronicity is low. The 

 prepatent period may vary from 2 to 38 

 days. Paraense (1947) saw exoerythro- 

 cytic stages in the endothelial cells. Culex 

 qiiinqiiefasciatus was found to be a suit- 

 able experimental vector by Paraense 

 (1944), but Aedes aegypti and A. lepidus 

 are not. 



are elongate, at the end or side of the host 

 cell, and often displace the host cell nucleus 

 when oriented obliquely to it. This tendency 

 to take an oblique position differentiates P. 

 diirae from other avian species of Plas- 

 modium. The pigment granules are usually 

 large, round and black. The host cell is 

 not enlarged. The trophozoites are more 

 or less amoeboid. Presegmenters are 

 often at the end of the host cell. The mature 

 schizonts rarely displace the host cell nu- 

 cleus. The pigment granules are round, 

 black, up to 8 in number, and tend to be- 

 come clumped together in the mature schi- 

 zonts. Six to 14 (usually 8) merozoites 

 are formed. The host cell is not distorted. 



Pathogenesis : This species is highly 

 pathogenic. The Brazilian strain killed 

 75% of the infected young birds and 68% 

 of the adults in 15 days to 9 months, and 

 the Mexican strain killed 12 of 13 birds in 

 1 to 8 months. Affected birds do not show 

 any marked signs. Shortly before death 

 they appear listless and weak, with pale 

 combs. Their temperature is not eleva- 

 ted. There are deposits of pigment in the 

 liver and spleen. Versiani and Gomes 

 (1943) observed a large amount of peri- 

 cardial fluid, but Beltran (1943) did not. 



PLASMODIUM DURAE 

 HERMAN, 1941 



Disease : Turkey malaria. 



Hosts : Turkey. Purchase (1942) 

 produced a transient infection in baby 

 chicks. Simpson (1944) infected ducks of 

 various ages. This is probably a natural 

 parasite of some as yet unknown wild 

 African bird. 



Location : Erythrocytes. The exo- 

 erythrocytic stages are in endothelial cells. 



Geographic Distribution : Africa 

 (Kenya). 



Prevalence : Herman (1941) found P. 

 durae in 1 of 75 domestic turkeys in Kenya. 



Morphology : This species was des- 

 cribed by Herman (1941). The gametocytes 



Life Cycle : Purchase (1942) and 

 Simpson (1944) found exoerythrocytic 

 stages of P. durae in the endothelial cells 

 of the spleen, liver, lungs and brain of 

 turkeys. The prepatent period is 3 days 

 to 2. 5 weeks after intravenous injection and 

 12 days to 40 days after intramuscular in- 

 jection (Herman, 1941). Schizogony in the 

 erjTthrocytes apparently takes 24 hours. 

 The vectors are unknown (Huff, 1954). 



Pathogenesis : P. durae causes an 

 acute, often fatal disease in turkeys less 

 than a year old. Twelve out of 14 young 

 poults infected by Purchase (1942) died. 

 They showed some malaise and ruffled 

 feathers, but usually died without any acute 

 signs. Two naturally affected adult birds 

 showed signs of cerebral involvement, 

 emaciation, edema of the legs and high 

 blood pressure. 



At necropsy of acute cases (Purchase, 

 1942) the liver, spleen and kidneys are dark 

 and congested, the lungs slightly edematous, 

 and the pericardial cavity contains an excess 

 of clear fluid. The lumen of the duodenal 

 loop is light chocolate in color and its villi 

 are heavily laden with pigment. There is 

 injection of the superficial vessels of the 

 brain and meninges. 



In chronic, naturally infected birds, 

 the spleen is reduced in size, hard and 

 fibrous, the liver is firm, with chronic 

 congestion and much fibrosis. The villi of 

 the duodenal loop are packed with large 

 pigment granules. 



