Do nonpathogenic protozoa ever cause symptoms?
Endolimax nana, Iodamoeba bütschlii, Chilomastix mesnili, and Pentatrichomonas hominis (as examples) have been categorized as nonpathogens. Although rare, patients have been documented who have been symptomatic with a nonpathogen. However, it is sometimes difficult to determine from the case history the extent of the workup, including coccidia and the microsporidia. Before I would assign symptoms to nonpathogenic protozoa, I would certainly look for other proven pathogens.
