Chapter 3 



Protozoa parasitic in the digestive 

 tract (continued) 



Flagellata 



THE FLAGELLATES wliicli inhabit the digestive tract of 

 man are all minute organisms. They live in the lumen 

 of the intestine or in the mouth, by absorbing fluid sub- 

 stances as well as by engulfing solid food particles. The 

 trophozoites are able to move about only in fluid or semi- 

 fluid contents of the intestine, and under favorable cir- 

 cumstances multiply in large numbers. There is however 

 no definite evidence to suppose that any of these flagellates 

 is the cause of diarrhoeic condition. When the faeces be- 

 come normal, the flagellates disappear, and the cysts ap- 

 pear in their stead. As in Sarcodina, the trophozoite encysts. 

 The cvsts are voided in the faeces and able to live outside 

 the human host for variable lengths of time. Infection 

 begins when viable cysts enter the mouth of a person in 

 contaminated food or water. In the species in which the 

 encystment does not take place, the trophozoite appears 

 to be able to bring about new infection. 



1. Retortamonas intestinalis (Wenyon and 

 O'Connor 1917) 



Synonym: EmbacJomonas intesthmlis (Wenyon 

 and O'Connor) 



This flagellate appears to inhabit the lumen of the 



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