THE TELOSPORASIDA AND THE COCCIDIA PROPER 



223 



The serosal sui'face of the ceca of 

 heavily infected birds is cream colored. 

 The ceca contain a non-adherent, mucoid 

 or caseous, yellow plug on the 5th and 

 6th days. Caseous material composed of 

 oocysts and epithelial cells is sometimes 

 found in the feces on the 6th day, but the 

 ceca appear quite normal in another day 

 or two. Hawkins noted petechial hemor- 

 rhages in the cecal mucosa. 



Immunity : Turkeys which have re- 

 covered from an infection with E. mele- 

 agyidis have a high degree of immunity 

 according to Hawkins (1952). Clarkson 

 (1959a) found no cross immunity between 

 this species and E. adenoeides. 



EIMERIA MELEAGRIMITIS 

 TYZZER, 1929 



Host: Turkey. 



Hawkins (1952) was unable to trans- 

 mit this species to the bobwhite quail or 

 Hungarian partridge. Gill (1954) claimed 

 to have transmitted it to the chicken. 



Location : The asexual stages occur 

 mainly in the upper jejunum, but a few 

 are present in the duodenum and ileum as 

 far as the yolk stalk. The first genera- 

 tion schizonts lie below the host cell nuclei 

 of the epithelial cells of the glands. The 

 second generation schizonts develop in 

 colonies in the epithelial cells of the deep 

 glands but also spread up the sides of the 

 villi. They usually lie just beneath the 

 brush border of the cell but are some- 

 times found below the host cell nucleus. 

 The third generation schizonts are found 

 in the epithelial cells of the villi but never 

 in the glands. Most of them lie above the 

 host cell nucleus, but some are below it. 



The sexual stages are found mainly 

 in the epithelial cells at the tips of the 

 villi but also spread down the sides. The 

 great majority lie above the host cell 

 nucleus (Clarkson, 1959). 



Geographic Distribution : Presumably 

 worldwide. 



Prevalence : Quite common. Four 

 out of 22 outbreaks studied by Clarkson 

 and Gentles (1958) in Great Britain were 

 due to this species, and 3 to a mixture of 

 it and E. adenoeides. 



Morphology : The morphology of this 

 species has been studied especially by 

 Tyzzer (1929), Hawkins (1952) and Clark- 

 son (1959). The oocysts are subspherical, 

 smooth, 16 to 27 by 13 to 22 jj. with a mean 

 of 19 by 16fi; 150 oocysts measured by 

 Clarkson (1959) were 20. li 1.95 by 

 17.3tl.7j:i. A micropyle is absent. One 

 to 3 oocyst polar granules are present. 

 An oocyst residuum is absent. The sporo- 

 cysts are ovoid, with a Stieda body. A 

 sporocyst residuum is present. The 

 sporozoites have a colorless globule at the 

 large end. The sporulation time is 2 days 

 according to Hawkins (1952), 1 day at 26°C 

 according to Clarkson (1959). 



Life Cycle : Tyzzer (1929), Hawkins 

 (1952) and Clarkson (1959) studied the life 

 cycle of this species, the last using a 

 strain derived from a single oocyst. The 

 account below is that of Clarkson, which 

 is the most complete. The sporozoites 

 invade the tips of the villi and migrate 

 down the villi in the lamina propria until 

 they reach the glands. Young first gener- 

 ation schizonts can be found in the gland 

 epithelial cells as early as 12 hours after 

 infection, and many are mature by 48 

 hours. They usually measure 17 by ISfj, 

 and enlarge the host cell, pushing its 

 nucleus into the gland lumen. They con- 

 tain 80 to 100 merozoites which measure 

 about 4. 5 by 1. 5jj, and have the nucleus 

 at the larger end. 



The first generation schizonts rupture 

 and release the merozoites, which invade 

 the adjacent epithelial cells, forming col- 

 onies of second generation schizonts. 

 Most of these are mature by 66 hours 

 after infection. They measure 8 by 7 |i 

 and contain 8 to 16 merozoites which 

 measure about 7 by 1. 5/i and have the 

 nucleus near the center. 



Third generation schizonts may be 

 recognized as early as 72 hours after 



