CHAPTER V 



COCCIDIA 



I. Species Living in Man 



Historical. The coccidia are tissue parasites, but are 

 generally included among the intestinal protozoa because 

 they apparently are responsible for digestive disturbances 

 and the infective stages, oocysts, in their life-cycle 

 escape from the body in the feces of the host. Between 

 1858 and 1890, 10 more or less authentic cases of hu- 

 man infection with coccidia were recorded in the litera- 

 ture (Dobell, 1919b). In five of these cases the coccidia 

 were found in the liver, in 3 cases in the intestine and in 

 2 cases in the feces. No more infections with coccidiosis 

 were discovered until 191 5 ; then a number of cases were 

 reported by British protozoologists in soldiers from the 

 Eastern Mediterranean war area, and within the suc- 

 ceeding 5 years (191 5-1920) almost 150 cases were 

 recorded. Since then infections from various parts of 

 the world have been added until the number has now 

 reached about 200. In 19 19, Dobell concluded that ''there 

 are four distinct species of coccidia which may parasitize 

 man. These are (i) Isospora hominis Rivolta, 1878 

 (emend.), discovered by Kjellberg in i860, and recently 

 investigated by Wenyon; (2) Eimeria wenyoni n. sp., 

 a form discovered in 191 5 by Wenyon; (3) Eimeria 

 oxyspora n. sp., another new form, here described for 



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