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CHAPTER XVI. 



INTESTINAL PROTOZOA, &c. 



MANY protozoa are found in the intestines, and may 

 be discharged with the faeces. In coccidia infections, 

 either of the liver or intestinal mucosa, the fertilized 

 macrogametes are discharged in this manner. 



The more important of the human intestinal protozoa 

 are those associated with diarrhoea and dysentery. These 

 diseases are so often due to bacterial infections, and the 

 prevention of such diseases is so closely connected with 

 the disposal of sewage and the provision of a good water 

 supply, that they are best considered at the same time as 

 the diseases similar clinically, but due to vegetable 

 organisms in Part III. Only a brief reference to these 

 parasites and the diseases they cause will be given here. 



The protozoal organisms described as concerned in 

 the production of intestinal diseases are Sarcodina, such 

 the Amoeba coli; Flagellata, as Trichomonas hominis, 

 Lamblia intestinalis and various spirochaetae ; and Infusoria 

 (Ciliata), as the Balantidium coli (fig. 64). Of these the 

 most important is the Amoeba coli Entamceba histolytica 

 (f E. tetragena, Schaudinn). 



Other protozoa, especially Balantidium coli, which 

 invades the tissues, may cause ulceration and all the 

 symptoms of dysentery. 



Balantidium dysentery often commences as an occa- 

 sional attack of diarrhoea. In the more severe attacks 

 there will be persistent but remittent diarrhoea. The 

 parasites are found during the periods when there is 

 diarrhoea. Blood and mucus are present in all the 

 more severe cases and may be considerable in amount. 



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