Questionable clinical significance of Blastocystis hominis infection

Am J Gastroenterol. 1989 Dec;84(12):1543-7.


In the period from January 1986 to July 1988, Blastocystic hominis was found in moderate and numerous quantities in 103 (1.6%) of 6,262 stool specimens examined in our laboratory. There was no significant association of the detection of B. hominis with travel history or symptoms. Indeed, 20 patients (36%) with moderate to heavy infections had no gastrointestinal symptoms, and three symptomatic patients did not show clinical improvement after elimination of the parasite. Reexamination of stool samples revealed that eight untreated patients had spontaneous disappearance of B. hominis. We conclude that B. hominis probably is not responsible for clinical symptoms when detected, and additional investigations should be pursued for other etiologies of the patient's symptoms.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Animals
  • Eukaryota / pathogenicity*
  • Feces / parasitology
  • Female
  • Gastrointestinal Diseases / diagnosis
  • Gastrointestinal Diseases / drug therapy
  • Gastrointestinal Diseases / parasitology*
  • Humans
  • Male
  • Metronidazole / therapeutic use
  • Middle Aged
  • Prospective Studies
  • Protozoan Infections / diagnosis
  • Protozoan Infections / drug therapy
  • Protozoan Infections / parasitology*
  • Quinacrine / therapeutic use
  • Time Factors


  • Metronidazole
  • Quinacrine