Blastocystis hominis in a pig-tailed macaque: a potential enteric pathogen for nonhuman primates

Large numbers of Blastocystis hominis were found in fecal samples from a pig-tailed macaque (Macaca nemestrina) with chronic diarrhea that was refractory to conventional therapy. The animal's condition improved and fecal samples showed minimal numbers of Blastocystis hominis following therapy with an antiprotozoal agent. This organism, recently reclassified as a protozoa, appeared to be causally related to the diarrhea. The cytologic and ultrastructural features of the monkey Blastocystis were comparable to those reported for similar organisms from man.