Blastocystis spp., ubiquitous parasite of human, animals and environment

Blastocystis spp. is a worldwide protozoan parasite of human, animal and environment. Multiple ways are involved in its transmission, “fecal-oral, waterborne, foodborne, zoonotic and anthroponotic.” This parasite cycles in the large intestine of human and wide range of animals manifesting nonspecific clinical features. Blastocystis different morphotypes usually confuse microscopist and the genetic diversity (17 subtypes) of it forms a mysterious role in its pathogenicity. Gut bacterial microbiota and human immune response might control this parasite action as commensal, pathogenic or part of gut microbiota. Presence of Blastocystis in water definitely affects its drinking quality. An important issue needs governmental careful observation.