Overview

Blastocystis is a microscopic parasite that can live in your digestive tract. Researchers don't fully understand the role blastocystis plays, if any, in causing disease. Some people experiencing diarrhea, abdominal pain or other gastrointestinal problems have blastocystis organisms in their stool.

Most commonly, however, blastocystis organisms simply live in a person's digestive tract without causing harm.

Blastocystis may be transmitted through food or water or by contact with human or animal feces. Blastocystis infection is generally more common among people who live in or travel to developing countries and among people who work with animals.

Blastocystis in humans was once identified as a single species, Blastocystis hominis. Researchers have found several variations — either different species or different strains within a species. The scientific name used now is Blastocystis spp, an abbreviation that means "multiple species." A blastocystis infection is called blastocystosis.