208 



THE TELOSPORASIDA AND THE COCCIDLA PROPER 



Brackett and Bliznick (1950) found 

 that inoculation with 500,000 oocysts re- 

 duced weight gains of 2-week-old chicks. 

 Moynihan (1950) obtained similar results. 

 Becker (1959) found that 300,000 oocysts 

 produced only loss of appetite for 2 or 3 

 days and watery feces on the third day 

 after infection in White Leghorn chicks. 

 Morehouse and McGuire (1958) found that 

 infection of chicks with 100, 000 oocysts 

 retarded weight gains somewhat but did 

 not affect the final weight. Larger inocula 

 produced increasingly severe effects. 

 Single and multiple doses of 5 million or 

 more oocysts caused 6 to 75% mortality. 



The lesions produced by B.acervulina 

 are not as marked as with E. necatrix. 

 The intestine may be thickened and a 

 catarrhal exudate may be present, but 

 hemorrhage is rare. The maturing 

 oocysts lie massed in limited areas, and 

 form whitish or grey spots or streaks 

 running transversely in the intestinal 

 mucosa. In heavy infections the entire 

 mucosa may be involved and may appear 

 greyish, mottled and somewhat thickened. 

 Morehouse and McGuire (1958) described 

 a severe inflammatory reaction in chicks 

 infected with 1 to 20 million oocysts. The 

 intestine was edematous and thickened, 

 with extensive vasodilation and marked 

 reddening of the mucosa, and there was 

 also degeneration or necrosis and slough- 

 ing of the intestinal epithelium. 



EIMERIA MAXIMA 

 TYZZER, 1929 



Host : Chicken. 



Location : Middle and posterior 

 small intestine. 



Geographic Distribution : Worldwide. 



Prevalence : Common. 



Morphology : The oocysts are ovoid, 

 smooth or somewhat roughened, yellowish, 

 21 to 42 by 16 to 30 ji with a mean of 29 by 

 23 fx. A micropyle is absent. An oocyst 

 polar granule is present. An oocyst resi- 

 duum is absent. The sporocysts are 



elongate ovoid, 15 to 19 by 8 to 9 /i , with 

 a Stieda body. A sporocyst residuum is 

 absent. The sporozoites are 19 by 4ji, 

 with a conspicuous retractile globule 

 (Long, 1959). The sporulation time is 2 

 days. Edgar (1955) and Long (1959) found 

 some infective oocysts as early as 30 

 hours at 28' C. 



Life Cycle : The life cycle of this 

 species has been studied by Tyzzer (1929), 

 Scholtyseck (1959) and Long (1959), among 

 others. The schizonts are found above the 

 host cell nuclei or occasionally beside them 

 in the epithelial cells of the tips of the villi 

 of the duodenum and upper ileum. There 

 are 2 generations of schizonts, both of 

 which are relatively small, measuring 

 about 10 by 8 p.; they produce only about 8 

 to 16 merozoites each. Schizonts may be 

 present thru the 5th day. The second gen- 

 eration merozoites enter new epithelial 

 cells, where they round up and enter the 

 sexual phase of the life cycle. 



The sexual stages are found beneath 

 the host cell nuclei. As they become 

 larger, the host cells are displaced toward 

 the center of the villus and come to lie in 

 its interior. The mature microgametoc3^es 

 measure 30 to 39 by 22 to 33 jj. and form a 

 large number of biflagellate microgametes. 

 The macrogametes are somewhat smaller, 

 averaging 19 by 15fj, (Long, 1959). After 

 fertilization, they lay down an oocyst wall, 

 break out of the villus and are passed in 

 the feces. The prepatent period is 5 to 6 

 days, and the patent period is only a few 

 days. 



Brackett and Bliznick (1950, 1952) 

 reported that the maximum number of 

 oocysts produced per oocyst fed in their 

 experiments was 12,000. In a series of 

 3-week-old chicks, they found that 11,500, 

 2250 and 940 to 2900 oocysts were pro- 

 duced per oocyst fed when the inoculating 

 doses were 200, 2000 and 10,000 oocysts, 

 respectively. 



Long (1959) found that the number of 

 oocysts produced per oocyst fed varied 

 with the age of the birds and the inoculum. 

 With an inoculum of 10,000 oocysts it 

 averaged 128, 33, 176, 448, 1049 and 



