Blastocystis spp. are intestinal parasitic protozoa of humans and many other
organisms Using molecular approaches the taxonomy of Blastocystis was determined.
At present, this parasite is believed to belong to the subclass of Stramenopiles (or
Heterokonts), subgroup Opalinata. Blastocystis is the only Stramenopile known to be a
human parasite. For this reason it was classified first as Blastocystis hominis, but in the
light of new knowledge, the term of Blastocystis spp. is more appropriate In this
chapter epidemiology, life cycle and transmission, morphology and structure,
laboratory diagnosis including microscopy, culture and molecular techniques are
reviewed. Finally, clinical aspects, including the association with irritable bowel
syndrome and therapeutic approaches are considered.
Keywords: Blastocystis spp., Diagnostic method, Epidemiology, Human
infection, Immunology, Molecular epidemiology, Molecular subtypes,
Pathogenesis, Treatment.
