Entamoeba dispar: Could it be pathogenic

Abstract

Amebiasis is a disease caused by the protozoan parasite Entamoeba histolytica. This ameba can colonize the human intestine and persist as a commensal parasite, similar to Entamoeba dispar, an ameba considered to be non-pathogenic. The similarities between E. histolytica and E. dispar make the latter an attractive model for studies aimed at clarifying the pathogenesis of amebiasis. However, in addition to being an interesting experimental model, this relative of E. histolytica remains poorly understood. In the 1990, it was believed that E. dispar was unable to produce significant experimental lesions. This scenario began to change in 1996, when E. dispar strains were isolated from symptomatic patients in Brazil. These strains were able to produce liver and intestinal lesions that were occasionally indistinguishable from those produced by E. histolytica. These and other findings, such as the detection of E. dispar DNA sequences in samples from patients with amebic liver abscess, have revived the possibility that this species can produce lesions in humans. The present paper presents a series of studies on E. dispar that begin to reveal a new facet of this protozoan.

Differential detection ofEntamoeba histolytica,Entamoeba disparandEntamoeba moshkovskiiin faecal samples using nested multiplex PCR in west of Iran

“…In addition, Oliveira et al . found that E. dispar was commensal and non-pathogenic to humans [ 36 ]. Dvorak et al .…”

Inhibition of Amebic Lysosomal Acidification Blocks Amebic Trogocytosis and Cell Killing

“…Previous work, which was done before the discovery of amebic trogocytosis, has shown that weak bases inhibit amebic killing of human cells ( 16 ). Interestingly, studies comparing E. histolytica with the less-pathogenic species Entamoeba dispar have noted that acidification of the phagosomes takes significantly longer in E. dispar and does not reach the same level of acidification, also indicating a possible role for lysosomes in the pathogenesis of amebiasis ( 18 , 25 ). Indeed, chloroquine, a lysosomotropic weak base that impairs lysosomal acidification ( 26 ), has been used to successfully treat amebic liver abscesses ( 27 ).…”

Diagnosis of colonic amebiasis and coexisting signet-ring cell carcinoma in intestinal biopsy

“…Several investigations provide evidence that the prevalence of E. histolytica , derived from studies using conventional diagnostic tools (microscopy and/or culture), is often overestimated because of its epidemiological overlap with non-pathogenic E. species , and only a proportion of microscopically positive stool samples are true E. histolytica infections as confirmed by polymerase chain reaction assay[ 19 - 22 ]. However, given that E. dispar is generally considered non-invasive and thus related to asymptomatic infections (despite emerging evidence that E. dispar can acquire pathogenicity in the presence of bacteria and produce significant lesions in the human intestine and liver[ 23 ]), based on the clinical presentation, E. histolytica is likely the causative agent of dysenteric colitis and amebomas in the current case.…”