Eradication of Blastocystis in humans: Really necessary for all?

Parasitol Int. 2016 Dec;65(6 Pt B):797-801. doi: 10.1016/j.parint.2016.01.010. Epub 2016 Jan 15.


Blastocystis (initially named as Blastocystis hominis) has long been known as a protist without any clinical significance. However, there is now a huge pile of case reports where Blastocystis is blamed for the symptoms and the infection described in the patients. Introduction of the presence of as many as 17 Blastocystis subtypes while many infected individuals are non-symptomatic initially brought about the correlation between the subtypes and pathogenicity; however, the outcomes of these trials were not consistent and did not explain its pathogenicity. Today, it is mostly acknowledged that Blastocystis may colonize many individuals but the infection's onset depends on the interaction between the virulence of parasites and host's immune competence. Eradication of Blastocystis is essential in some cases where it is the only infectious agent and patient is suffering from some symptoms. In such cases, metronidazole is the drug of choice but its efficacy is relatively low in some cases. Other agents used include trimethoprim-sulfamethoxazole, paromomycin, and furazolidone. Recent studies on the interactions between human health and the role of gut microbiota introduces new data which may significantly change our point of view against some protists, which we tend to see as "parasites requiring urgent eradication for cure". May the presence or absence of some Blastocystis subtypes necessary for human health, or is the absence or presence of certain Blastocystis subtypes in human gut is associated with certain diseases/infections? The answers of these questions will surely guide us to select patients requiring treatment against Blastocystis infection in future.

Keywords: Blastocystis; Eradication; Metronidazole; Microbiota; Review; Treatment.

Publication types

  • Review

MeSH terms

  • Antiparasitic Agents / pharmacology
  • Antiparasitic Agents / therapeutic use*
  • Blastocystis / drug effects
  • Blastocystis / immunology
  • Blastocystis / physiology*
  • Blastocystis Infections / drug therapy*
  • Blastocystis Infections / pathology
  • Blastocystis Infections / prevention & control*
  • Disease Eradication*
  • Drug Resistance
  • Humans


  • Antiparasitic Agents