210 



THE TELOSPORASIDA AND THE COCCIDIA PROPER 



of pathological significance under normal 

 field conditions. Tyzzer (1929) observed 

 neither signs nor gross lesions in young 

 chickens given tremendous and repeated 

 doses of sporulated oocysts. Becker 

 (1959) found neither lesions nor diarrhea 

 in infected chickens. Joyner (1958) found 

 that weight gains of 6- to 26-day-old birds 

 fed 500,000 oocysts were reduced, while 

 38% of 29 6-day-old chicks died after 

 being fed 2. 5 million oocysts. 



praecox is probably no more pathogenic 

 than E. mitis. 



EIMERIA HAGANI 

 LEVINE, 1938 



Host: Chicken. 



Location: Anterior half of small in- 



testine. 



EIMERIA PRAECOX 

 JOHNSON, 1930 



Host : Chicken. 



Location : Upper third of small in- 

 testine. 



Geographic Distribution : Probably 

 worldwide. 



Prevalence : Common. 



Morphology : The oocysts are ovoid, 

 smooth, colorless, 20 to 25 by 16 to 20(1 

 with a mean of 21 by 17 /i. A micropyle 

 is absent. An oocyst polar granule is 

 present. Oocyst and sporocyst residua 

 are absent. The sporulation time is 2 

 days. 



Life Cycle : Tyzzer, Theiler and 

 Jones (1932) studied the life cycle of this 

 species. The endogenous stages occur in 

 the epithelial cells of the villi, usually 

 along the sides of the villi and below the 

 host cell nuclei. There are 2 generations 

 of schizonts, the second of which appears 

 as early as 32 hours after infection. 

 Later development is irregular, both sex- 

 ual and asexual stages being seen together. 

 The prepatent period is 4 days, and the 

 patent period is short, 4 days or a little 

 more in the absence of reinfection. 



Pathogenesis : This species is essen- 

 tially non- pathogenic. Tyzzer, Theiler 

 and Jones (1932) were unable to cause 

 death with heavy doses of oocysts, altho 

 they did observe a mucous cast containing 

 large numbers of oocysts at the end of the 

 infection. Becker (1959) found that E. 



Geographic Distribution : 

 America, India. 



North 



Prevalence : Rare. This species has 

 apparently been reported in the United 

 States only by P. P. Levine (1938) in New 

 York and Edgar (1955) in Alabama. Gill 

 (1954a) found it in 2. 5% of 120 chickens in 

 India. 



Morphology : The oocysts are broadly 

 ovoid, smooth, 16 to 21 by 14 to 19/i with 

 a mean of 19 by 18 fj, (18 by 16. 5 jm accord- 

 ing to Edgar, 1955). A micropyle is ap- 

 parently absent. An oocyst polar granule 

 is present. No other morphological data 

 are known; this species was differentiated 

 from other chicken coccidia by cross-im- 

 munity tests. The sporulation time is 1 

 to 2 days. Edgar (1955) found sporulated 

 oocysts as early as 18 hours at 29" C. 



Life Cycle : Unknown. The prepatent 

 period is 7 days according to Levine (1938) 

 or almost 6 days according to Edgar (1955). 



Pathogenesis : This species is only 

 slightly pathogenic. Levine (1938) ob- 

 served pin-head size hemorrhages and 

 catarrhal inflammation in the anterior 

 half of the small intestine. There were 

 also a few hemorrhages in the lower small 

 intestine. Later, however, Levine (1942a) 

 referred to this species as non- pathogenic, 

 stating that 300, 000 oocysts had no effect 

 on experimentally infected birds. 



COCCIDIOSIS IN CHICKENS 



Epidemiology : Infections with a 

 single species of coccidium are rare, and 

 mixed infections are the rule. Eimeria 



