Pathogenicity of Blastocystis hominis, a clinical reevaluation

Turkiye Parazitol Derg. 2007;31(3):184-7.


Blastocystis (B.) hominis was considered to be a member of normal intestinal flora in the past, but in recent years it has been accepted as a very controversial pathogenic protozoan. In this study, 52 individuals whose stool examination revealed B. hominis were evaluated for clinical symptoms. Metronidazole was administered for 2 weeks to the patients infected with B. hominis. After 2 weeks of treatment they were called for a follow-up stool examination. No other bacteriological and parasitological agents were found during stool examination of these patients. The frequency rate of intestinal symptoms was 88.4% in the B. hominis cases. Abdominal pain was the most frequent symptom (76.9%). Diarrhea and distention followed at a rate of 50.0% and 32.6%. Intestinal symptoms may be seen frequently together with the presence of B. hominis and this protozoan may be regarded as an intestinal pathogen, especially when other agents are eliminated.

MeSH terms

  • Abdominal Pain
  • Adolescent
  • Adult
  • Animals
  • Antiprotozoal Agents / pharmacology
  • Antiprotozoal Agents / therapeutic use
  • Blastocystis Infections / drug therapy
  • Blastocystis Infections / parasitology*
  • Blastocystis Infections / physiopathology
  • Blastocystis hominis / drug effects
  • Blastocystis hominis / pathogenicity*
  • Child
  • Child, Preschool
  • Diarrhea
  • Feces / cytology
  • Feces / parasitology
  • Female
  • Humans
  • Leukocyte Count
  • Male
  • Metronidazole / pharmacology
  • Metronidazole / therapeutic use
  • Middle Aged


  • Antiprotozoal Agents
  • Metronidazole