The role of Blastocystis sp. as an etiology of irritable bowel syndrome

Introduction Blastocystis is a common intestinal protozoan of humans and animals. The role of this organism as a pathogen is still controversial. The Blastocystis infection could be asymptomatic or could include nausea, anorexia, abdominal pain, flatulence, and/or diarrhea. An association between Blastocystis infection and acute chronic digestive disorders such as irritable bowel syndrome (IBS) have also been suggested. Aim In this article, the evidence concerning Blastocystis infection causing IBS will be discussed, with regard to the subtypes of the parasite. Discussion An association between the parasite and IBS has been suggested in the recent literature. The explanations of pathogenicity include an intra-subtype difference (ST4 and ST7) with regard to protease activity during infection with Blastocystis . Conclusions It is most likely that the presence of Blastocystis in the human intestine plays a significant role in IBS. On the other hand, it is still not known if Blastocystis is the etiological agent responsible for this type of gut dysfunction. There are many reports in the literature which are mutually exclusive. More studies are needed to confirm this hypothesis.