Effect of Feeding Raw Liver to Dogs Infected with Endamoeba Histolytica.

Abstract

Cleveland and Sanders 1 have stated that, when Endamoeba histolytica is grown in vitro on slants of liver infusion agar covered with fresh horse serum-saline 1-6 containing rice flour, a medium is provided in which the organism will carry on its entire life cycle. Encystation begins within 18 to 24 hours after the slant is inoculated and continues for 3 days or more, the actual time for encystation requiring 4 to 6 hours. They believe that “there is evidently something in the dehydrated media … which makes encystment possible,” whereas “the whole process of growth and encystation may be upset by the use of contaminated media,” i. e., by bacteria or yeasts in the culture media.

We have utilized the Cleveland-Sanders technic in cultivating our Tulane canine strain (Strain A) of E. histolytica and have been able to confirm their results as to the value of the liver infusion medium. In a representative case an extremely rich growth of trophozoites was obtained within 72 hours after the culture was started. Four days later no active forms were found, but there were cysts in great abundance. This culture was continued by inoculation with the cysts through 3 subcultures and then discontinued. In another case abundant growth of trophozoites was maintained for 9 days, when no trophozoites but large numbers of cysts were found. These latter were utilized through 5 subcultures, after which an overgrowth of Giardia and bacteria was apparently responsible for the death of the amebae.

Daily observations of our canine strain of E. histolytica, cultivated in vivo over a period of 10 months has failed to produce a single instance in which other than trophozoites were passed in the stool.