CHAPTER XXVII 



SPOROZOA. CILIATA 



THE sporozoa, as their name implies, are characterized by their 

 method of reproduction through spore formation. They are 

 strict parasites and are for the most part harmless; only a few 

 species are known to be pathogenic. The organisms vary greatly in 

 size, in structure, and in development. Certain forms are so small 

 that several may be contained within a single red blood corpuscle, 

 while others are large enough to be seen with the naked eye. Some 

 members of the group show ameboid movements during certain 

 phases of their existence, but the pseudopodia serve only as a means 

 of locomotion and not of nutrition. Their life history is more or 

 less complicated, one period being passed in one host and the other 

 period within the body of another species ; or different phases of 

 development may take place in different tissues of a single host. 



The known pathogenic forms occur among five different genera : 

 Coccidia, Sarcosporidia, Nosema, Babesia, and Plasmodia. 



Coccidia. A disease of rabbits occurs in epidemic form due 

 to Coccidium cuniculi ; a few cases of human infection have been 

 reported. 



Sarcosporidia. Organisms belonging to this group affect 

 mainly swine and cattle; a case of human sarcosporidiosis was 

 reported in 1909 in Panama. 



Nosema. So far as is known no infection attributable to the 

 nosema has occurred in man. One member, however, is of interest 

 in that it is the cause of pebrine, the infectious disease of silkworms, 

 to which Pasteur devoted several years of study. 



Babesia (Piroplasma). Babes was the first to observe 

 the parasites in the blood of Roumanian cattle. Later, in 1893, 

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