Investigations Concerning Amoebic Dysentery

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  • Department of Tropical Medicine Harvard Medical School Boston, Massachusetts



  1. 1.Specimens of feces containing cysts of E. histolytica but no trophozoites were injected directly into the large bowel of kittens. Using material not more than six days old, 6 out of 8 animals were infected.
  2. 2.The circumstances of the experiments suggest very strongly indeed that excystation occurred in the large bowel.
  3. 3.Additional evidence was obtained that stasis is an important factor in producing an infection of the intestine with E. histolytica.


  1. 4.Kittens were infected with E. histolytica and the large intestine was then deprived of its normal supply of water by placing a ligature around the gut.
  2. 5.The amoebae disappeared promptly in three animals in which this procedure was carried out early in the course of the infection. The progress of the disease was not checked in one animal in which the operation was delayed for several days after symptoms appeared.


  1. 6.According to our conception, the cysts of E. histolytica when ingested by mouth are carried rapidly by peristalsis through the small bowel and set up lesions at points of stasis in the large intestine. In 3 kittens amoebic infection of the colon readily invaded the ileum when the ileo-colic sphincter was rendered functionless. Under the conditions of these experiments, the sphincter was an important factor in the mechanical protection of the ileum.
  2. 7.In 3 animals, ligation of the small bowel and inoculation of active amoebae immediately above the ligature failed to produce an infection. This failure to produce a primary infection of the small intestine suggests that the environmental conditions in the ileum are somewhat unfavorable for the development of amoebae. It does not necessarily indicate that the mucosa per se of the ileum is less susceptible than that of the colon to the action of E. histolytica.