Which Entamoeba species are pathogenic?

Updated: Jul 19, 2019
  • Author: Vinod K Dhawan, MD, FACP, FRCPC, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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The genus Entamoeba contains many species, some of which (ie, E histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba bangladeshi, Entamoeba polecki, Entamoeba coli, and Entamoeba hartmanni) can reside in the human interstitial lumen. Of these, E histolytica is the only one definitely associated with disease, although a 2012 report suggested E moshkovskii to be the causative agent of diarrhea in infants. [17, 18] Although E dispar and E histolytica cannot be differentiated by means of direct examination, molecular techniques have demonstrated that they are indeed 2 different species, with E dispar being commensal (as in patients with HIV infection) and E histolytica pathogenic. [17]

It is currently believed that many individuals with Entamoeba infections are actually colonized with E dispar, which appears to be 10 times more common than E histolytica [17] ; however, in certain regions (eg, Brazil and Egypt), asymptomatic E dispar and E histolytica infections are equally prevalent. [4] In Western countries, approximately 20%-30% of men who have sex with men are colonized with E dispar. [17]

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