Dientamoeba fragilis n. g., n. sp., a new Intestinal Amoeba from Man

Abstract

It is now becoming generally recognized that there are three different amoebae which may be present in the human bowel—the harmless Entamoeba coli(Lösch) Schaudinn and “Entamoeba” nana Wenyon and O'Connor, and the pathogenic E. histolytica Schaudinn. We have discussed these three species in an earlier paper (1917), and there noted their chief distinctive characters. In the present paper we shall describe a fourth and much less common species which we have recently encountered. It differs in some respects so conspicuously from the others that it appears to us necessary to place it not only in a new species, but even in a new genus. We propose therefore the new name Dientamoeb fragilis for our amoeba, but we can discuss the question of nomenclature most conveniently after we have described the organism itself. This, therefore, we shall now do.

Dientamoeba fragilis, One of the Neglected Intestinal Protozoa

“…Precysts have recently been described by Stark et al (10); however, previous publications have described these stages in the past (2,11,12). These stages range from 3.5 to 5 m in diameter, have one or two nuclei, and contain finely granular and uniform cytoplasm (12).…”

“…The trophozoite is characterized as having one nucleus (20% to 40%) or two nuclei (60% to 80%) (2). The nuclear chromatin is usually fragmented into three to five granules, and there is normally no peripheral chromatin on the nuclear membrane (Fig.…”

“…fragilis was first seen in 1909 by Charles Wenyon after the examination of his own fecal specimen; however, the organism was not described until 1918 by Margaret Jepps and Clifford Dobell (2,3). They indicated that the organism was an amoeba with a binucleate structure, which was described as fragile and disintegrating quickly outside the body.…”

Emerging from Obscurity: Biological, Clinical, and Diagnostic Aspects of Dientamoeba fragilis

“…The name Dientamoeba fragilis refers to the fact that it is an enteric ameba with the curious characteristic of being binucleate and that it tends to degenerate rapidly after excretion in stool (65). It was also classified as an ameba by Chatton (20), who included it in the family Entamoebidae, where it remained for the best part of 50 years.…”

Molecular Testing for Clinical Diagnosis and Epidemiological Investigations of Intestinal Parasitic Infections

“…2C) was first described in 1918 as an amoeba of the intestinal tract of humans (109). Later, by means of antigen and ultrastructural studies and analysis of rRNA, however, the organism was reclassified as a trichomonad flagellate although lacking external flagella (110)(111)(112).…”