CHAPTER XI 



" GROUSE DISEASE " CONTINUED COCCIDIOSIS 



By Dr H. B. Fantham 



Part I. — The Morphology and Life History of Eimeria [Cogciuiuh) avium 

 A Sporozoon causing a Fatal Disease among Young Grouse ^ 



I. Introduction. 



The subject of this memoir is a microscopic, protozoal parasite, which infests the 

 lining epithelium of the alimentary canal of Grouse. It belongs to the Coccidia, a 

 group of parasitic protozoa, many of which are known to occur in the digestive 

 tracts of both vertebrates and invertebrates. These minute organisms reproduce 

 by means of resistant spores, and belong to that class of the protozoa known as the 

 Sporozoa. The Coccidia are of economic importance, inasmuch as they destroy the 

 mucous membrane of the intestine of the host, thereby setting up enteritis which is 

 accompanied by diarrhoea, and very often has a fatal eifect upon the unfortunate 

 animal harbouring the parasites, especially if the host be young. 



Such a disease — termed Coccidiosis — has long been known in rabbits, and is 

 often fatal. Occasionally Coccidiosis occurs in man. The life-history of a coccidian 

 parasite is complicated. There are two phases in the life-cycle : — (1) 'i- multiplica- 

 tive phase within the cells of the gut-epithelium of the host, and (2) a reproductive 

 phase leading, after a sexual act, to the formation of resistant spores adapted for 

 life outside the body of the host. The spores so formed are the means of spreading 

 the parasite, and lead to the infection of fresh hosts. The two phases were formerly 

 considered to belong to separate parasites ; but the occurrence of alternation of 

 generations in the life-cycle of Coccidia was first suggested by R. Pfeiffer in 1892, 

 conjugation was discovered in Coccidia by Schaudinn and Siedlecki (1897), and the 

 complete life-cycle was demonstrated with a wealth of morphological and cytological 



' Reprinted from the Proceedings of the Zoological Society of London, 1910. 



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