THE TELOSPORASIDA AND THE COCCIDIA PROPER 



211 



Fig. 27. Morphology and developmental stages of species of Eiiiici'ki from the chukcn. 

 1-4. Stages in development of oocysts of Eiiiicyia IcnclUi. 5-7. Stages in 

 development of oocysts of Eiiueria initio. 8-9. Stages in development of 

 oocysts ol Eiuieria aceyvnlina. 10-13. Stages in development of oocysts of 

 Eiiucria maxima. 14-17. Stages in development of oocysts of Eiiiicna 

 iiccalyix. 18. Developmental stages in cecal epithelium 7 to 9 days after in- 

 fection, oo = oocyst, sch = third generation schizont. nier = third generation 

 nierozoite. mi = microgametocyte. ma = macrogamete. (From Tyzzer, 1929 

 in the Aincyicaii Junyiial uj Hygiene, published by the Johns Hopkins Press). 



tenella is the most pathogenic and impor- 

 tant species. In recent years, however, 

 control of this species with coccidiostats 

 has revealed more and more coccidiosis 

 due to E. )iccalri.x. The other species 

 may contribute to the total picture. E. 

 brunelli is markedly pathogenic but un- 

 common. E. niaxiiiia and E. acerviilina 

 are slightly to moderately pathogenic. 

 Both are conunon. E. )iiitis and E. 

 praecox are common but non- pathogenic. 

 E. hagani is rare and only slightly if at 

 all pathogenic. Weiiyonella galliiiae is 

 rare but moderately pathogenic; it has 



been found so far only in India. Crypto- 

 sporidiiiiii tyzzeri is rare and non-patho- 

 genic, laospora gallinae is rare if it is a 

 chicken parasite at all, and is presumably 

 non- pathogenic. 



Coccidiosis is primarily a disease of 

 young birds. Older birds are carriers. 

 Birds become infected by ingesting oocysts 

 along with their food or water. Under 

 farm conditions, and even in the laboratory 

 unless extreme precautions are taken, it 

 is practically impossible to avoid exposure 

 to at least a few oocysts. 



