Blastocystis hominis est un organisme intestinal fréquent et cosmopolite, considéré auparavant comme une levure saprophyte et classé actuellement comme parasite. La contamination s’effectue par voie orale. L’association de B. hominis et de troubles digestifs (diarrhée, douleurs abdominales, flatulence) a été rapportée par divers auteurs mais contestée par d’autres. Ces parasites sont retrouvés dans les selles surtout après un voyage tropical ou la consommation de nourriture mal lavée. Avant d’affirmer la pathogénicité de B. hominis, il est important d’éliminer les autres causes de troubles digestifs.

Blastocystis hominis is a common and worldwide intestinal organism. Previously considered as a harmless yeast, it is classified as a protozoan since about forty years. This parasite is transmitted by fecal-oral route. The association of B. hominis with intestinal disorders (diarrhea, abdominal pain, flatulence) was reported by some authors but remains controversial by others. These parasites are recovered from stool specimens, mostly after a recent tropical travel or the consumption of untreated food. With metronidazole treatment, patients become asymptomatic with negative stools. However, before asserting the pathogenicity of B. hominis, other causes of intestinal disorders must be intensively searched.