THE TELOSPORASIDA AND THE COCCIDIA PROPER 



207 



middle and upper small intestine. These 

 became more severe the next day but had 

 disappeared from the upper and middle 

 intestine. The lower small intestine and 

 large intestine were hyperemic and hem- 

 orrhagic, there was epithelial sloughing, 

 and the intestinal contents were watery 

 and blood-tinged. The tubular part of the 

 ceca was involved, and the dilated portion 

 was plugged with dehydrated material. The 

 epithelial denudation was most probably 

 caused by the asexual stages, and was 

 most prominent on the 4th day. Signs of 

 illness continued until the 6th day. 



Field outbreaks of the disease were 

 studied by Levine (1943). The disease 

 occurs most commonly in chicks 4 to 9 

 weeks old. The mortality is high, and 

 typical necrotic lesions are present. We 

 have seen the same condition in field out- 

 breaks in Illinois. 



EIMERIA ACERVULINA 

 TYZZER. 1929 



Host : Chicken. 



Location : Anterior small intestine. 



Geographic Distribution : Worldwide. 



Prevalence : Common. 



Morphology : The oocysts are ovoid, 

 smooth, 12 to 23 by 9 to 17 jii with a mean 

 of 16 by 13 p.. A micropyle is absent. An 

 oocyst polar granule is present. An 

 oocyst residuum is absent. The sporocysts 

 are ovoid, with a Stieda body but without a 

 sporocyst residuum. The sporulation 

 time is 1 day. Edgar (1955) found that the 

 minimum sporulation time for this species 

 at 28° C was 17 hours. 



Life Cycle : The life cycle of this 

 species was described by Tyzzer (1929). 

 The schizonts are found in the epithelial 

 cells of the villi of the anterior small in- 

 testine, where they lie above the host cell 

 nuclei. The gland cells may also be in- 

 vaded. Sometimes more than one parasite 

 is found in a cell. The schizonts produce 

 16 to 32 merozoites which measure about 



6 by O.SjLL. There are at least 2 and pos- 

 sibly more asexual generations. Asexual 

 reproduction lasts longer than in E. teiiella. 



The sexual stages occur above the 

 host cell nuclei in the epithelial cells of 

 the villi and to a lesser extent in the gland 

 cells in the anterior small intestine. They 

 first appear 4 days after infection. The 

 microgametocytes are relatively small, 

 measuring 11 by 9ju. 



The prepatent period is 4 days, and 

 oocysts continue to be produced for rela- 

 tively longer than with some other chicken 

 coccidia. 



Brackett and Bliznick (1950) found 

 that the maximum number of oocysts pro- 

 duced per oocyst fed in their studies was 

 72, 000. This occurred in a group of 3- 

 week-old birds fed 2000 oocysts each. In 

 another experiment in which similar birds 

 were fed the same number of oocysts, 

 only 35,000 oocysts were produced per 

 oocyst fed. Oocyst production was lower 

 with both larger and smaller inocula. 

 Following inoculation with 200, 10,000 and 

 20,000 oocysts, respectively, 9000,35,000 

 and 7, 600 oocysts were produced per oocyst 

 fed. 



Pathogenesis : E. acerindina is gen- 

 erally considered only slightly pathogenic, 

 but very large inocula may cause severe 

 signs and even death. Generally, however, 

 this species causes only a temporary set- 

 back. Dickinson (1941) found that admin- 

 istration of as many as 25 million oocysts 

 to pullets produced only a temporary drop 

 in weight and temporary cessation of egg 

 production. Between 4 and 9 days after 

 infection, the birds were droopy, ate rel- 

 atively little and passed slimy, mucoid 

 feces. Peterson (1949) reported losses 

 from E. acerindina infection in the Pacific 

 Northwest in older birds 3 to 4 weeks after 

 they had been brought in off the range and 

 placed in houses. The birds lost weight, 

 egg production ceased, the combs shriveled 

 and keratin pigment disappeared. There 

 were few if any deaths. After about 6 

 weeks the birds recovered and egg produc- 

 tion returned to normal. 



