Experimental Infection of Guinea Pigs with Endamoeba Histolytica

Abstract

Summary 1. Acute amebiasis was produced in young guinea pigs by the inoculation of trophozoites of Endameba histolytic strain No. 200 directly into the cecum. 2. The mortality rate varied from 40 to 75 per cent, depending on the diet. Animals fed a ration of rat pellets and fresh kale had almost twice the rate of fatal infection as those fed rabbit pellets and fresh kale. 3. Eighty-four per cent of the animals that died had diarrhea and all had progressive weight loss. 4. Amebic ulcers and other lesions were found at autopsy in the cecum and frequently in the colon of all of the 99 animals that died 3 to 29 days after inoculation and in only 3 of 57 survivors killed for study at 30 days. No amebic lesions were found in the liver or other organs. 5. Histopathological studies were made on ulcerated lesions from 13 infected guinea pigs. In six animals the ulcers were confined to the mucosa, in three they extended into the submucosa, in three into the muscularis, and in one into the serosa; one animal showed a perforation. There is evidence that the amebae may reach the deeper layers by way of ulcerating glandular crypts which extend into lymphoid follicles lying in the submucosa.