The Occurrence of Endamoeba Polecki, Prowazek 1912, in Macaca Mulatta and in Man

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During a study of the occurrence and treatment of natural infections of E. histolytica in Macaca mulatta, another amoeba was encountered which produces only mononucleate cysts, but which possesses rod-shaped chromatoidal bodies and nuclear structures which may be similar to those of E. histolytica. Judged on the basis of morphology this amoeba appears to be identical with E. polecki Prowazek 1912 of the domestic pig and with E. chattoni Swellengrebel 1914 of monkeys. An amoeba with similar morphological appearances has also been found in man.

E. polecki often possesses a spherical or ovoidal inclusion mass in the encysted stage and this structure differentiates it from cysts of E. histolytica or of E. coli.

E. polecki appears to be a commensal in the domestic pig and in the monkey. When found in the monkey it does not respond to amebicidal therapy as readily as does E. histolytica.

The similarity of these amoebae as here reported is based only on morphological structure since there has been no opportunity to attempt reciprocal animal infection experiments.

Author Notes

From the Department of Bacteriology and Parasitology, School of Medicine, University of Southern California and from the Laboratories of the Los Angeles County Hospital, Los Angeles, California.

From the Parasitology and Mycology Section, Division of Medicine, University of California Medical School, San Francisco, California.