Blastocystis Hominis, Intestinal Parasite or Nonpathogen Microorganism?

Blastocystis hominis is a worldwide distributed microorganism with no definite host. In addition to human beings it has been diagnosed in variety of animals. This organism which is abundantly found in routine stool examinations and also 'in some cases has been identified as a factor causing severe diarrhea, earlier regarded as a fungi. Later it was distinguished as cyst of intesinal Trichomonas and finally about twenty years ago as a parasite protozoan of digestive tract. For a definite remark about the characteristics of this enigmatic microorganism and its evaluation further studies are necessary.