Some similarities between the dystentery amoeba of the monkey and of man. ∗

Abstract

The dysentery amoeba of the monkey and that of man are so similar in structure that some regard them as probably being the same species, though other investigators have given them different species names. In an attempt to procure experimental evidence on this question two monkeys found to be amoeba-free were fed cysts of E. dysenteriae of man. Examination of the feces during a period of three months and of histological sections following autopsy showed the presence of cysts and trophozoites of E. dysenteriae, morphologically and racially indistinguishable from the amoeba fed, thus indicating that the dysentery amoeba of man may be experimentally established in the monkey. Subsequently, two cats, six months and seven months of age respectively, found negative for protozoa by preliminary examination, were given rectal injections of monkey feces containing cysts of the dysentery-like amoebae of a naturally infected monkey, using the technique of Boeck and Drbohlav. 1 Two months later, autopsy of the cats showed the amoebic infection to be well established in the upper colon and cecum, where there was excessive mucous, pronounced hyperemia, and a distinct thickening of the gut wall. Trophozoites of amoebae, many of which contained red blood corpuscles, were found in great numbers in these regions and histological sections showed necrosis of the mucosa and penetration of the amoeba into the tissue. Amoebae from the infected colon of the cats were planted into the L. E. S. medium of Boeck 1 and at the time of writing seventeen successful subcultures have been made on alternate days and the cultures show no signs of dying out.