A number of amoebae (class Sarcodina) can be found in human feces. These include the Entamoeba spp.: Entamoeba histolytica, E. dispar, E. moshkovski, E. bangladeshi, E. coli, and E. hartmanni. The first four species are morphologically identical, but of the four, only E. histolytica has been definitely determined to be pathogenic. E. dispar is morphologically identical to E. histolytica, but non-pathogenic. E. coli and E. hartmanni are also considered non-pathogenic.
Commensal amoeba of other genera include Endolimax nana and Iodamoeba butschlii.
This section will focus on the pathogenic parasite, E. histolytica, but information will be given regarding ways to differentiate them from some of the other common harmless commensals.
One note about the commensals - although they do not cause disease in most people, they are indicative of the fact that the person has clearly consumed something with fecal contamination. Therefore, even the commensals should always be noted and reported.
