GIARDIASIS 



Localization in the duodenum. What factors are re- 

 sponsible for the locaHzation of giardias in the duodenum 

 is a question still unsolved. All of the other intestinal 

 flagellates proper of man live in the large intestine, ex- 

 cept vi^hen a few specimens under extraordinary condi- 

 tions succeed in migrating forward into the ileum. It is 

 interesting here to refer again to the apparent aggrega- 

 tion of the trophozoites of G. canis in the duodenum of the 

 guinea-pig into the stomach of which they were inocu- 

 lated (see p. 155). The sucking disc no doubt is an im- 

 portant organelle of attachment and some such means 

 of maintaining the organisms against the downward 

 force of peristalsis is certainly necessary before the duo- 

 denum can be used as a habitat. The lumen of the glands 

 are also of assistance, and, that this haven of refuge 

 is taken advantage of by giardias, is shown by their pres- 

 ence there in sections of infected duodenum. Perhaps 

 these flagellates react strongly to currents and are ca- 

 pable of moving up the intestine until stopped by the 

 pyloric sphincter. Giardias have no visible method of 

 ingesting solid food particles and no such material has 

 been observed in them ; they must therefore absorb nutri- 

 ment through the general surface of the body. What sub- 

 stances are necessary for this purpose is unknown, and 

 up to this time all efforts to duplicate conditions in the 

 duodenum so as to cultivate the organisms outside of 

 the body have resulted in failure. 



(3) Pathogenicity. Giardiasis. The terms lambliasis, 

 giardiasis and flagellate diarrhea all refer to a pathologi- 

 cal condition supposed to be due to the presence of giar- 

 dias. Most of the infected hosts do not exhibit any symp- 



159 



