"GROUSE DISEASE " COCCIDIOSIS 257 



parasitic worms and Coccidia, as a means of inoculation of 

 harmful bacteria, is of far-reaching importance, and probably of 

 wide application in the elucidation of certain intestinal diseases. 



While observation seems to indicate that intestinal Coccidi- 

 osis may so injure the gut that bacteria are allowed to pass 

 into the circulation, it is not suggested that " Grouse Disease " 

 is essentially an infection with these bacteria. The direct effect 

 of the parasite is alone quite sufficient to produce fatal results. 



Probably Coccidiosis set up in the duodenal wall is sufficient Coccidiosis 



, . , . , . -. , , duodenal 



to kill very young chicks, e.g., chicks eight to ten days old, 



while older chicks dying at the age of about four to six weeks 

 may have partially recovered from duodenal Coccidiosis, but 

 succumb to Coccidiosis in the caecum (typhlitic Coccidiosis). 

 In cases of intense duodenal Coccidiosis, merozoites are found 

 free in the intestinal contents, and even in freshly shed faeces. 



The onset of sporogony of the Coccidium (Eimeria avium) 

 means, as a rule, either the recovery or the death of the infected 

 chick. When the oocysts pass out from the body of the host, 

 the epithelium of the gut may be able to regenerate itself, 

 and the bird gradually increases in weight, and makes partial 

 or entire recovery. This recovery is sometimes aided by 

 infiltration of connective tissue into the lesions. If, however, 

 the infection has been heavy, the epithelium cannot regenerate 

 itself, and the bird becomes exhausted and dies. 



Young chicks are far more susceptible to Coccidiosis than Suscepti- 

 adult birds. Very young fowl chicks (up to' eight days old) Q^ase of 



die in a few days after being fed with coccidian oocysts. Chicks various 

 first dosed with cysts when fourteen days old do not succumb 

 so readily ; they may live for some weeks, or some may become 

 chronics, when daily examination of their faeces shows periodic 

 small crops of oocysts. 



Older chicks are more likely to recover from Coccidiosis. 

 For example, a Grouse chick aged thirteen weeks was fed on 

 oocysts, and when killed three weeks later very few Coccidia 

 were observed. A young Grouse was picked up dead on the 

 moors in Inverness-shire and was received on September 15th, 



