Entamoeba coli, E. hartmanni, E. polecki, Endolimax nana, and Iodamoeba buetschlii are generally considered nonpathogenic and reside in the large intestine of the human host. Both cysts and trophozoites of these species are passed in stool and considered diagnostic. Cysts are typically found in formed stool, whereas trophozoites are typically found in diarrheal stool. A total of 1,868 patients submitted stool specimens; 1,246 were from MSM (628 HIV positive and 618 HIV positive) and 622 from non-MSM were examined over a 36-month period. A total of 651 (52.2%) stool specimens from MSM were positive for protozoa compared with 85 (13%) from non-MSM.
Colonization of the nonpathogenic amebae occurs after ingestion of mature cysts in fecally-contaminated food, water, or fomites. The trophozoites multiply by binary fission and produce cysts, and both stages are passed in the feces. Because of the protection conferred by their cell walls, the cysts can survive days to weeks in the external environment and are responsible for transmission. To help prevent infection:
•Avoid raw vegetables when in endemic areas, as they may have been fertilized using human feces.
•Boil water or treat with iodine tablets.
•Avoid eating street foods especially in public places where others are sharing sauces in one container