THE TELOSPORASIDA AND THE COCCIDIA PROPER 



227 



(1958) illustrated them as lying above the 

 host cell nuclei. 



Geographic Disti'ibution : 

 America, Great Britain. 



North 



Prevalence : Quite common. Fifteen 

 out of 22 outbreaks studied by Clarkson 

 and Gentles (1958) in Great Britain were 

 caused by this species and 3 by a mixture 

 of it and E. iiieleagriniitis. 



Morphology : The oocysts have been 

 described by Moore and Brown (1951) and 

 Clarkson (1958). They are similar to 

 those of E. ))ieleagridis and E. gallopa- 

 vonis. They are ellipsoidal, sometimes 

 ovoid, smooth, 19 to 31 by 13 to 21 fi with 

 a mean of 26 by 17 /i. A micropyle is 

 sometimes present. One to 3 oocyst polar 

 granules are present. An oocyst residuum 

 is absent. The sporocysts are elongate 

 ovoid, apparently with a Stieda body. A 

 sporocyst residuum is present. The sporo- 

 zoites contain a clear globule at the large 

 end. The sporulation time is 1 day. Edgar 

 (1955) found sporulated oocysts as early as 

 18 hours at 29° C. 



Life Cycle : Clarkson (1958) studied 

 the life cycle of this species, using a 

 strain derived from a single oocyst. First 

 generation schizonts can be found in the 

 epithelial cells as early as 6 hours after 

 infection. They become mature 60 hours 

 after infection; by 66 hours most of them 

 have released their merozoites, altho a 

 few remain up to 84 hours. The mature 

 first generation schizonts measure 30 by 

 18 |i and contain about 700 merozoites 

 measuring 4. 5 to 7 by 1 . 5 fi , with a central 

 nucleus. 



The second generation schizonts be- 

 come mature 96 to 108 hours after infec- 

 tion. They measure 10 by lOjj and contain 

 12 to 24 merozoites measuring about 10 by 

 3|j., with the nucleus a little nearer the 

 rounded than the pointed end. 



Sexual stages can be found as early as 

 114 hours and recognized as early as 120 

 hours after infection. The mature macro- 

 gametes measure about 20 by 18 /i and con- 

 tain many large, plastic granules which 



f.tain black with Heidenhain's hematoxylin. 

 The mature microgametocytes are about 

 the same size as the macrogametes. 



The prepatent period was given by 

 Moore and Brown (1951) as 112 hours. 

 Edgar (1955) found oocysts in the feces as 

 early as 104 hours, and Clarkson (1958) 

 found that the prepatent period varied from 

 114 to 132 hours in 30 birds. 



The patent period is 7 to 8 days accord- 

 ing to Moore and Brown (1951). Clarkson 

 (1958) found that very few oocysts were 

 passed more than 14 days after infection, 

 and none after the 20th day. 



Pathogenesis : This species is highly 

 pathogenic. Moore and Brown (1951) were 

 able to kill 100% of experimental poults up 

 to 5 weeks of age with large doses of spor- 

 ulated oocysts. Older poults developed a 

 severe enteritis with few or no deaths. 

 Clarkson (1958) and Clarkson and Gentles 

 (1958) observed mortalities of 0%, 0%, 

 45% and 100%, respectively, in 3-week-old 

 poults fed 10,000, 25,000, 100, 000 and 

 200,000 oocysts; of 33% in 6-week-old 

 poults fed 1 million oocysts; and of 0% in 

 11 -week-old poults fed 3 million oocysts. 

 Birds which did not die had decreased food 

 consumption and weight gains. 



Poults develop signs of anorexia, 

 droopiness and ruffled feathers during the 

 4th day after experimental infection. If 

 death occurs, it is usually on the 5th or 

 6th days but may be a little later (Moore 

 and Brown, 1951). 



The gross lesions have been studied 

 by Moore and Brown (1951), Clarkson 

 (1958) and Clarkson and Gentles (1958). 

 The intestines appear quite normal until 

 the 4th day. The walls of the lower third 

 of the small intestine, ceca and rectum 

 become swollen and edematous, petechial 

 hemorrhages which are visible from the 

 mucosal but not from the serosal surface 

 appear, and the lower intestine becomes 

 filled with mucus. 



During the 5th day, most of the ter- 

 minal intestine is congested and contains 

 large numbers of merozoites and long 



