470 VETERINARY BACTERIOLOGY 



Coccidium tenellum 



Synonyms. It is possible that this organism does not differ 

 from that of the rabbit, in which cases the name given would be 

 reduced to a synonym of Coccidium cuniculi. 



Disease Produced. Coccidiosis in domestic fowls and in birds, 

 blackhead or enterohepatitis in turkeys, white diarrhea (at least 

 some types) in chicks, possibly roup in fowls. 



These diseases have been studied by a great number of inves- 

 tigators, and many theories of their causation have been de- 

 veloped. Hadley and others have seemed recently to show quite 

 conclusively that they are cases of avian coccidiosis, and the various 

 organisms described by others as causal were secondary invaders 

 or developmental stages of the organism in question. 



Distribution. The disease probably has a very wide distribu- 

 tion over the United States and Europe, but adequate data are 

 not at hand for a determination. It is certainly known from 

 many localities in the eastern States. 



Morphology and Life-history. The life-history is typical for 

 Coccidium as outlined above. The adult coccidial cyst is oval 

 or ellipsoidal. It measures about 14 by 21 f*. 



Pathogenesis. A considerable number of infections in the 

 domestic fowls have been ascribed to this organism. A mild in- 

 fection may not result in marked symptoms. An intestinal and 

 cecal infection in the young chick has been found to be a potent, 

 if not the principal, cause of white diarrhea, which causes such 

 heavy losses in certain localities. A similar infection in adult 

 chickens may also prove fatal. This is particularly true of the 

 turkey, which is unusually susceptible. The principal symptoms 

 are three in number diarrhea, progressive languor or stupor, and 

 loss of appetite with pronounced emaciation. The disease may 

 be acute or chronic, but is quite generally fatal. Some fowls 

 may harbor the organisms for long periods without any apparent 

 symptoms. 



Hadley has also shown that this same organism is probably 

 the cause of roup. In this disease the tissues infected are the 

 mucous membranes of the head. The infection results in the 

 " inflammation of and exudate from the orbital sinus, nasal 

 lachrymal duct, nasal chamber, mouth, pharynx, larynx (some- 



