a species of Blastocystis widespread among humans, formerly considered harmless, now recognized as a rare cause of diarrhea and other intestinal symptoms and eosinophilia when found in heavy infections or immunocompromised hosts.
Blastocystis hominisA single-celled protozoan parasite isolated from 5–10% of stool specimens in developed countries and up to 50% of specimens in developing countries, especially in those who work with animals.
B hominis was long known to cause gastrointestinal disease in immunocompromised patients—e.g., recurrent diarrhoea, episodic vomiting, abdominal colic; B hominis infection may be misdiagnosed as irritable bowel syndrome.
Experts have proposed dropping hominis, the species name for Blastocystis sp. subtype nn (where nn is the number of each species group). It is phylogenetically included in the group Stramenopiles, which also includes brown algae, mildew, diatoms and the bacteria that caused the Irish potato famine.
Blastocystis hominis(blăs′tō-sĭs″tĭs hŏm′ĭn-ĭs)
A protozoan once thought to be a harmless commensal in the human gastrointestinal tract but now believed to be an intestinal parasite that produces diarrhea, abdominal pain, bloating, and weight loss in some people.